From Editors Mailbox.. Asa C.
In case you haven’t yet received the riving-knife gospel, this safety device is a vast improvement over those inconvenient splitters and blade covers that U.S. manufacturers called “safety equipment” and we all tossed in the corners of our shops. A riving knife moves up, down, and sideways with the blade, and can even be adjusted below the top of the teeth, so it NEVER has to come off the saw for any type of cut.
| A splitter that stays on the saw. A riving knife moves up, down, and side to side with the blade, and best of all, it can be adjusted below the top of the blade so it can stay on even for non-through-cuts (slotting, tenoning, etc.). |
Therefore it stays on the machine, protecting the user from the worst tablesaw safety hazard: kickback. Kickback not only hurls a board at you at 100-plus mph, it can also drag your hand into the blade. With a riving knife in the saw kerf and no fear of kickback, you can concentrate on keeping your fingers away from the blade.
****
I will challenge the statement of no fear of kickback by simply having a riving knife in the saw kerf. I think it is highly mis-leading to imply it and dangerous to those that would believe it to be “gospel” because it was printed in a leading magazine forum. I had a TS with a riving knife before the current rage and had 2 kick-backs.
A riving knife is just “one” added feature that can help eliminate kickback and not the “final solution”. Kickback comes in several forms and unless you account for all you are have not purchased an insurance policy that covers your total needs.
I do believe that those that have used them or have them might agree. Just thought for discussion if you wish. I have to go to my shop to add a few features other than a riving knife to a new TS I just got at IWF that add a few more beneficial ways to avoid kickback.
And even with there additional features that do help counter kickback… there is still no guarantee that kickback is totally eliminated!
Just my opionion…
Sarge..
Replies
Based on that photograph, about all I could say is that the likelihood of having your hand kicked back as the saw gobbled it up would at least be somewhat remote. Sorry, but when I see a raw saw blade with no crown guard or covering at all safety is that last thing that comes to mind.
Well Sarge, it is a fact that a riving knife cannot eliminate kickback. A correctly installed riving knife only reduces the chance of a kickback occurring; a second, vitally important factor relies upon the worker using the saw in a safe manner-- which points to proper training, good work habits and other factors such as using the right blade for the job, eg, use a rip blade for ripping, not a cross cut blade.
I bet you were just waiting for me to jump all over that one.
I can't recall seeing any text anywhere in any Fine Woodworking publication, in print, online or elsewhere that implies a riving knife eliminates kickback incidents. I presume you have seen text somewhere in a Taunton publication that says something along those lines, but I haven't. Your 'quotation' needs to be specific and attributable to give it real weight. Slainte.
Richard Jones Furniture
The first part of Sarge's post is the quote, apparently from "The Editor's Mailbag."
Yes Boss, but what is the the Editor's Mailbbag, and where can I read it? Is it a magazine, and if it is what is the publication date, issue number, page number and the author, if named? If it is an online source what is the URL, page number if relevant and author's name, again if given?
I guess I'm being a bit of a stickler for accurate academic type referencing so that I can go and check the source for myself. Sarge's post seems to include a quotation, and perhaps an image from his source but he doesn't give me enough information to go to the source. To offer informed comment I really ought to be able to see the original text. Slainte.Richard Jones Furniture
It's not in the magazine Richard, it's here on line in this forum as I read it just this morning and copied to paste. When you first log in and click on Fine Woodworking... look at all the little messages.. etc. until you see New Tools at IWF just below the pictures of the two TS inserts...
Just click on it and see for yourself... I simply copied and pasted to where I put the 4 stars and then my comments.
Regards...
Sarge..
Okay Sarge. After you'd posted the bit you quoted and your criticsm the ideal thing would have been to point us all to the URL saying something like the following:
The rest of Asa Christiana's Editor's Mailbox, Great News at IWF 2008 posted August 29, 2008 is available at http://blogs.taunton.com/n/blogs/blog.aspx?webtag=fw-editorsblog
That would have made the source clear for everyone, and made it easy to go and read the original text. That is a part of the Taunton website I seldom visit so I am pretty ignorant of what appears on those pages; so ignorant that I had no idea what or where the Editor's Mailbox was until I followed your directions in the post I'm replying to. Slainte.
Richard Jones Furniture
*Edit. Now that I too have read the original text and know for sure what was written I can see how the text could be interpreted to read that a riving knife will completely prevent kickback, which is not true.
The troubling phrase for me is, "With a riving knife in the saw kerf and no fear of kickback, you can concentrate on keeping your fingers away from the blade." The emphasis is mine. I'm not an English major, just a dumb woodworker with a pedantic streak, ha, ha.
Edited 9/3/2008 4:04 pm by SgianDubh
Sorry for not pointing the exact source out Richard. I am no literary gaint by any means. Just another dumb WW but one that does realize that a riving knife alone will not get you to the "promise land". ha.. ha...
I sincerely believe that good was intended by the article but the way it was worded left much grey area to be deciphered by the reader. Unfortunately many still don't understand a riving knife function even with the current rage to get them on American saws.
Given the choice of one of the new saws with a riving knife to "help" protect me from kickback... or the old type American saw with standard splitter but armed with a short fence.. assist boards left.. crown guard..etc.... I would chose the latter. A riving knife is great but far from the "holy grail". :>)
Regards and thanks for teaching me about riving knives.. short fences.. friction supports.. etc. years ago... The info you passed then has been well used since then in my personal shop.
Regards to the Nag Queen and daughter..
Sarge..
.....any set of words that causes this much discussion and confusion among a few must be suspect.However, I do think we all are of similar thought, to wit: never drop your guard when your saw is on.:) Jeff in Texas
As Boss stated and pointed out.. the statement made in the Editors Mailbox is printed in my first post. I simply would not post an assumption as I frankly don't have time to explain why I would assume the re-write what was written to get a discussion started.
Without going into detail about the other things that can help reduce the chances of kickback (short fence.. feather or spring boards.. crown gaurds.. etc. etc.... which you taught me two of those whether you realize it or not) I will just give the author a chance to explaiin why it was written as it was.
Regards...
Sarge..
Maybe you can link it. I can't find the Editor's Mailbox although I'm sure you just copied and pasted the quoted section.
TIA
Look at my last post to Richard I just posted when he ask you the question. The article is under New Tools IWF just down and under the pictures of the two TS inserts by Tom Begnal. Basically you can just back-space your computer until the open page you get just before you hit All discussions..
Regards...
Sarge..
http://blogs.taunton.com/n/blogs/blog.aspx?webtag=fw-editorsblog
Here is the link
ASK
Clearly, no matter what safety equipment you do or do not have installed on your table saw, the less you expose yourself to risk, the safer you are. The accident that took off the first joint of my left thumb happened with a guard on the saw and while using a pushstick. The problem was poor proceedure, youth and inexperience, and a boss who was in a terrible hurry and made me think that was my problem. The simplest solution, including the use of appropriate safety devices is:
1 Wear eye protection.
2 Stand back from the saw far enough that you would have to change your stance to actually put your hand in the blade. Never change your stance without considering why.
3 NEVER, under any circumstances, put your hand past the blade. Use wooden pushsticks, featherboards, holddowns, etc. to keep work against the fence. The other major accident I have seen was caused this way, and cost a friend most of his fingers and his career.
4 Keep your body out of the line of the blade, or possible path of a kickback.
5 Teach newcomers that time is less important than safety, and that they have to be their own best protection.
There are probably a few more, but it would be hard to harm yourself if you keep those things in mind.
Oh, that is not good. FWW editors should know better! There's a similar overstatement at Wikipedia, where they state simply "A riving knife prevents a phenomenon known as kickback." I tried to edit it, but ran into logistical problems and gave up, too time-consuming.
Relax and give in to Darwin. It's our only hope.
I would have given up also Jamie. I suppose that at some point in each of our lives... one has to use his common sense (if one has any) and realize that just because it is printed doesn't necessarily make it so! I believe that the printed word comes from someone that puts his pants on the same way I do and is prone to making human errors daily.
So... if any doubt.... do some examination to confirm what you might find questionable.
Sarge..
Agreed. It's also nonsense that the blade can be adjusted below the level of the teeth so that the riving knife "NEVER" need be removed. On my saw at least there is minimal adjustment possible, and that mostly lateral. The knife stays in a fixed relationship to the blade. It MUST be removed for cuts using the conventional 8" dado set, because it sticks up about 2".
To be fair to manufacturers, they don't promote this particular gospel. The mistake is Asa's. SC, General, PM etc provide as their primary riving knife one that is taller than the blade, and comes with a blade guard and pawls, so that both major causes of kickback are covered. If you don't like the pawls or the blade guard it's fairly easy to replace them with a crown of your own devising, and a better guard. The short riving knife illustrated is provided for non-through cuts, or for when cutting narrow stock that a guard would hinder. I leave this knife on when using a GRRRipper for instance.
Jim
I'll be a stickler here, because it's important. The lot of you have misread the passage quoted. The passage says "no fear of kickback" which, at least in the English I know, does not say "kickback is eliminated". Nor do I think that it means that. I think it means that with a riving knife in place, you won't worry as much about kickback, which will allow you, as the passage does say, to "concentrate on keeping your fingers away from the blade."
Now I know that the usual suspects will roast me for defending FWW and Asa. But you must understand that when you set out to criticize another person you should at least criticize him for what he has actually said or done, rather than what you think he has said or done. You should keep in mind, that you, like every person, is fallible. Perhaps it is your understanding, and not his statement, that is mistaken.This is my personal signature.
Edited 9/3/2008 2:49 pm ET by MKenney
Your message is addressed to Sarge, but I believe I took Asa's meaning exactly, to the point of quoting his exact words. I understand "no fear of kickback" to mean that kickback will never occur. "No" means "no." My understanding of English is that of a retired English professor.
Jim
No might mean no, but "no fear of kickback" does not necessarily mean "kickback is eliminated."By the way, the fact that you're a retired professor doesn't mean your right. I'm one too (and it doesn't make me right either).This is my personal signature.
Edited 9/3/2008 3:02 pm ET by MKenney
I'll leave it to everyone else to judge what was meant by an unequivocal statement. I'm sure the author is quite capable of elucidating exactly what he meant, and will do so. The subject is important because the message given to those unacquainted with riving knives is that an inherently dangerous practice -- using a tablesaw without pawls or a crown guard -- is safe if you keep your fingers away from the blade. It isn't.
Jim
"No might mean no, but "no fear of kickback" does not necessarily mean "kickback is eliminated." Oh my, I feel a HUGE laugh coming on. What?! -- There may be kickback, but the riving knife means we don't need to fear it, just take it in stride? You must be kidding!
Take note, now, I'm most often accused of being overly-protective of the powers that be at Taunton, but I'm jumping on this one with both feet. The passage as quoted by Sarge was way out of line and should never have passed the very first look-see by the most junior of editors, period. The fact that it was ever even written means that someone who's either clueless, asleep or perhaps under the influence is writing articles they shouldn't. How's that for strong? My accusation may be over the top, but succumbing to such sensationalistic nonsense by whomever put that statement in black and white is nonsense.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Edited 9/3/2008 10:07 pm by forestgirl
There are many bad things that might happen to you in life, but you shouldn't (and don't need to) fear them all. I could be struck and killed by a car on my next bike ride, but I don't fear it. I could be killed in a car accident tomorrow, but I don't fear it. I could run my thumb over a jointer blade tomorrow, but I don't fear. Of course, I certainly make sure that I ride safely, drive safely, and use the jointer safely to cut down on the likelihood that I would be the cause of some misfortune. But the fact that I recognize the potential for harm does not mean that I need to fear that harm. To assert that I should is laughable. And if I did, I would never leave the comfort of my home, except for my fear of carbon monoxide poisoning, or a house fire.With a riving knife properly installed and properly used, I see no need to fear kickback. Could it still happen? I don't know, but I'm willing to say yes for the sake of argument. I still don't fear it. If I were using a tablesaw with no knife or any other safety device I would certainly fear kickback.And of course, I should make it explicitly clear that although I am an editor at Fine Woodworking, I am here expressing my own beliefs on the matter. I did not write the blog entry in question. However, I don't find it as objectionable or outrageous as many of you seem to. My primary point of even wading into this thread, was to prompt a more careful discussion of the blog. Heck, ya'll might want to even consider whether you could be wrong about kickback not being eliminated. It never hurts to rethink your beliefs, even if, in the end, you discover only that you were right all along.This is my personal signature.Edited 9/3/2008 10:52 pm ET by MKenney
Edited 9/3/2008 10:53 pm ET by MKenney
I think you are confusing fear with fear induced paralysis. I would assert that fear is a necessary component of everyday life in woodworking and in all the other aspects you mentioned. A false sense of security ie. lack of fear has been the cause of many accidents and injuries.
With the false sense of security and lack of fear the riving knife alone is giving you it is possible you will never install a crown guard or short fence or use featherboards or hold downs.
A lack of fear of collisions with cars could lead you to feel you were safe in a crosswalk or bike lane resulting in a lack of attention to your surroundings. As evidenced daily in the world a lack of situational awareness due to false confidence and lack of fear can have deadly consequences.
I am curious as to what part of this thread you perceived as careless on the part of the posters. It seems to me that a lot of thought and care was given to the majority of the posts. One might be easily given to think that this is an attempt to stifle criticism.
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
Thank you, Don, I am really far to tired tonight to respond reasonably and thoughtfully to this stuff. It seems like so much nonsense!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I'm pretty pooped myself tonight but I just could not let that slide by. Been a busy couple of months, hope it lasts for a while!
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
Lacking fear is not the same thing as having a false sense of security. For example, I am simply not afraid of getting in a car accident. But that does not mean that I don't drive carefully.I know that kickback is a possibility when using a tablesaw, but I don't fear it. That doesn't mean I have a false sense of security or lack respect for the tablesaw. It just means that I do not respond to the possibility of kickback with that particular emotion.As for attempting to stifle criticism, that's absurd. I haven't once told anyone not to comment. I haven't even implied it. All I've done is attempted to encourage more thoughtful criticism. But at this point I'm no longer willing to participate. Here's why. Regardless of what I say in defense of FWW, it'll be seen as homerism, as an attempt to stifle criticism (if you really think I or anyone here tries to do that, then you're not reading the threads you participate in--which are frequently extended complaints about FWW), or some such other non-sense.I say again and be done with it. I don't think the original post was a fair criticism. I know that many of you think that the blog entry was claiming that kickback is eliminated by a riving knife. I pointed out that that is not a clear as you (plural) think.
This is my personal signature.
We can play word games forever. Remember the "it depends on what your definition of 'is' is"? But the quote makes it clear that the point was if you have a knife you are safe (for the most part) from kick back and implied that you would be safe while using a saw with only said knife. And we all know that while a knife is a HUGE safety improvement it still needs other things (such as a guard, and prowls sp?) to help it along. And the quote did not make this clear. So their is room for improvement on the quote. IF this was Joe average saying this it would be fine, but coming from someone at FWW it is not a good quote and should be cleared up.
So if you want to agree with the quote because you think it is safe and all, fine but lets try to keep the alternate meanings of the quote to a dull roar. I all ready have to listen to the Mayor and his lawyers try that TV so I am a little sensitive to the whole attempt to redefine what was said with alternate definitions. (The joys of living around Detroit).
Doug M.
You're right about the word games, though I don't think many of us were playing. The OED says "... in mod. use the sense of the sb. is often weakened; thus for fear of = 'in order to avoid or prevent' ". Similarly if I were to say there's no fear of my winning the lottery, a discussion of whether or not I was afraid would be irrelevant: the phrase means "no chance." When a kid says "no fear" he means "no chance" or "no way." That's the sense in which all but one of us understood the editor's blog. I'm reminded of the old joke about the fond mother watching her soldier son on parade: "Look, father, everyone's out of step but our Johnny."
Jim
Well said, Jim. I noted that MK is somewhat vague in an earlier post in response to your statement that you are a retired english professor. He stated he was also. Did he mean he was a retired professor? Must be very smart (or was terminated) he's only 35. Or did he mean he is also a professor?Best regards,JoePS If MK was able to retire at age 35 then we best pay close attention to everything he says.
Yes, I am a former college professor, but I wasn't fired. I left for a job I enjoy far more. I'm an editor at Fine Woodworking now. But feel free to continue to make wild assumptions about me.This is my personal signature.
Clearly, you've got your hands full.
Well said, Jim. I noted that MK is somewhat vague in an earlier post in response to your statement that you are a retired english professor. He stated he was also. Did he mean he was a retired professor? Must be very smart (or was terminated) he's only 35. Or did he mean he is also a professor?
If MK was able to retire at age 35 then we best pay close attention to everything he says
Somebody has been reading waaaaaay too many true crime detective magazines
Ha Ha Ha Ha Ha
Lee
Thanks Joe.
I wouldn't blame anyone for opting out of that particular ratrace. You're likely to be stuck in a commonroom listening glumly to colleagues who are still working out how many angels fit on the head of a pin. (Everybody knows it's 5, 061,233)
I had the opposite career course, past 35 when I returned to grad school, past 40 when I started teaching. I figured that being a prof was a bit like marriage, the last card in the pack. It was what you did when you were good for nothing else. Many profs are haunted by Shaw's jibe: those who can, do; those who can't, teach. And you get paid less than the guy on the assembly line.
Woodworking kept me sane...ish.
Just kidding
Jim
Jimurock:
Now that I see that MK is an FWW editor, all is clear, allbeit I think somewhat misguided.
I think your number of angels is incorrect unless that is the total number of angels. All of the angels will fit on the head or the point of a pin for they have no mass ;-).Keep the faith,Joe
C, I think y'all have the wrong slant here. That copy was probably written by a copywriter who has little to no sawdust in his socks. The advertisers are twice delighted, first that they look golden for their new equipment and second that they didn't write that copy and it is FWW that gets the first law suit when Joe new bee loses two fingers. BTW I just checked, they have not changed the copy yet--where are the lawyers when ya need them. Paddy
Come on guys. I've retired hundreds of times. Think I'll do it again tomorrow.
Well if the bind forms fast you have little to no time to stop it, However a lot of time you can see/feel/smell it starting to come on and in these cases you can put in a wedge (Either stop the saw or have someone else in the room. Working with my father a lot this is something we have done (because we can always call the other person over to put in the wedge and we keep wedges close at had.
The kick back I have encountered most is the one with either the trapped piece of wood or the cut off (more often the trapped wood between the blade and the fence or a skinny piece out side of the blade) getting tossed straight back. This happened to a friend of mine about the 5th time he used my table saw (or any saw for that matter) And he still is not really into using one.
Doug M
Wood that starts to bind badly enough to notice before it's too late should simply be finished off with a handsaw. Gasp and horrors. Physical labor.
I can't think of an easier or safer solution. A doo-dad free solution, assuming you don't consider a handsaw to be a doo-dad which I'm sure some people do.
Turn the saw off and get to work; a board or two by hand every now and then won't hurt anybody's delicate sensibilities I hope. ForestGirl's screwdriver will work fine in this scenario and it's my personal favorite kerf-opener when handsawing.
Edited 9/5/2008 3:13 pm ET by BossCrunk
If someone isn't using a riving knife, hopefully they are using a splitter. If the splitter does its job, the wood binds on the splitter making it hard or impossible to push the board through, but also preventing any kickback. Turning off the saw and shoving a small scrap or wedge in the kerf that has already cleared the splitter before continuing often works fine to allow the cut to be completed. FWIW
I use a brett guard and griptite featherboard, by the way. Together with the splitter, this makes for a reasonably safe ripping operation in my experience.
I think it would be a missed opportunity to slow it down and smell the roses. I don't like stopping and restarting tablesaws with lumber on board. And no, I don't need the blow by blow on how to do it. I know how to do it. But I still don't like doing it. And I also don't like pulling it off and re-feeding it up to the stop point and continuing the cut.
I figure that in a fight between me, unruly lumber, and a five horsepower tablesaw I'm going to lose every time. I pick fights I can win - like with a scraper or a rasp or something like that.
Edited 9/5/2008 3:31 pm ET by BossCrunk
I think my contractor saw (PM64) only has like 1.5 HP. so maybe that accounts for my recklessness? ;-)
I must add this isn't something I've needed to do very often. Maybe one in 100 rips or more.
Exactly. Even a committed power tool aficionado could hand rip a board that often.
"Wood that starts to bind badly enough to notice before it's too late should simply be finished off with a handsaw."
Exactly. Though I'd probably use the bandsaw or circular saw.Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
"then you're not reading the threads you participate in--which are frequently extended complaints about FWW), or some such other non-sense."
What kind of B.S. is this? If you are referring to my posts then you are way off the mark, if you are referring to all of us then you have a very low opinion of Knots and it's denizens.
Maybe you ought to do a little research before making these ridiculous pronouncements.
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
I say again and be done with it. I don't think the original post was a fair criticism. I know that many of you think that the blog entry was claiming that kickback is eliminated by a riving knife. I pointed out that that is not a clear as you (plural) think.... MKenny
***
Again MK.. the first post was not criticism at all as I have already pointed out to you. It was simply asking for clarification of a very vague statement that could lead an entry level to believe that by having a riving knife they are safe to proceed without any other safety aids. And yes you pointed out that is is not as clear as you (plural) may think. But no clarification has been given at this point by the people that did write. Is it not the responsibility of the people that wrote the article to make it clear what they do mean? The alternative of not doing so could mis-lead someone with little experience to have an accident that could be avoided by not having been "crystal clear".
So... where is the clarification and if you deem the statement un-clear would it not be the responsibility of a leading WW magazine that influences many WW to clarify it? But the article stands today so many more that have seen the discussion can be possibly mis-lead.
You say we should use more careful thought as to what we write.. shouldn't the editors and proof-readers be more careful in their thoughts of what they write also as they carry far more influence than someone as I that works in a shop 8-10 hours a day. We are all prone to error regardless of beginner or experienced.
Perhaps the difference is some will admit they make an error and try to correct it regardless of their status... perhaps some won't. Perhaps!...
Sarge..
Sarge, I took your original post to make a valid point: while riving knife is extremely effective at reducing what is perhaps the most common cause of kickback (pinching at the back of the blade), lest anyone think riving knife is the ultimate security that utterly eliminates any chances of kickback, beware that kickback can occur in other ways that the riving knife does not address or prevent. Good point.
This thread has gone off in such weird ways since then. Some folks looking to beat up Asa; other bemoning the lack of other safety feature on the pictured saw (here's a clue: the pic was meant to show the riving knife); others seemingly proud they don't use this or that safety device; and on and on.
In case any newbies are trying to make sense of this, I'd condense the advice as:
- riving knives are excellent - get one if you can - but make sure to add other safety features such as a well set fence, feather boards, blade guards, pauls, etc.
- if you can't have a riving knife, use a splitter (along with the other safety devices)
Excellent video showing the kickback phenomenon:
http://www.metacafe.com/watch/910584/table_saw_kickback_demonstration/
Edited 9/5/2008 12:09 pm ET by Samson
Me thinks you said it well. I have, since a kid, heard the saying "you don't need to fear it, you just need to respect it." That doesn't work for me. Fear keeps me from trying insane things that would promote my demise. I fear rattle snakes, for example. However, that doesn't stop me from wandering the sage brush of Eastern Washington. I do watch were I am going [and sitting] though. Fear doesn't stop me from trying new things, but it often slows down my trying them before I am ready. Being a grown up does not mean living without fear. I means, as much as anything else, learning to walk through the fear and appreciating its value.
MK,
You, me and Chris, we don't fear no steenking keekback!
Ray
Over this past weekend, My Young Bride and I were able to spend some time with good friends of long standing in another State. My good friend and his eldest son are fellow woodworkers, and I showed them the FWW SawStop video. Neither my friend nor his son has previously seen the video, and both were very impressed with the blade brake.
My friend's son is a charge nurse on the emergency surgical unit of a large hospital and voiced the opinion that the SawStop technology would have averted dozens of severe accidents each year in his hospital alone. Most of us, however, do not have a SawStop in our shop.
This nurse says that woodworking accidents--particularly woodworking accidents accidents involving table saws--are generally due to one of two factors: 1) people drinking while they are using motorized tools, or 2) "mature" people who don't realize that their reflexes aren't quite what they once were.
Will a riving knife help to make a table saw safe? Of course, but the most important safety factor in any shop continues to be our own due diligence.
Jim you do rock. And you're right. That was how I took "no fear of..." as well.
I would most be most appreciative if you would go back and read post #10 to Sgain Dubh (Richard Jones). Read carefully the last sentence of the post that was made before you posted to me.
"I will give the author a chance to explain why it was written as it was"..That is what I said in that post.. If you read the original post by me #1 you will note that I stated that ....
43264.1
I will challenge the statement of no fear of kickback by simply having a riving knife in the saw kerf. I think it is highly mis-leading to imply it and dangerous to those that would believe it to be "gospel" because it was printed in a leading magazine forum. I had a TS with a riving knife before the current rage and had 2 kick-backs"... Sarge
Simply put I don't know what he meant by the way it was written but I can tell you many will interpret it to mean that a riving knife will eliminate kickback. I am not attacking Asa who I met last week but simply asking him to clarify exactly what was meant. Upon re-reading the article it was compiled by FWW authors and Asa may not have written it.
But if he puts his name at the top he should have read it before it was printed and they have a paid staff of proof-readers to do the same. So... what was the true intended meaning? If it was that a riving knife will eliminate kickback entirely.. that is simply wrong.
If it was as you guessed that it would eliminate fear of kickback to concentrate on keeping your hands away from the blade... then that should have been stated as such as the current printing leaves much grey area that can be mis-interpretted as I originally pointed out.
Again.. instead of assuming... I will just give the author a chance to explain why it was written as it was. Or have I already said that? Back to the shop where I do not fear kickback and keep my hands away from the blade and I do it with a standard splitter an a few other pre-cautions as a short fence.. spring-board left.. crown guard.. friction support surfaces for long stock and I always do what I was taught back in 1963 HS shop class...
KEEP THE LANE CLEAR...
But.. still no guarantee of not getting kick-back.. :>)
Sarge..
Again, an assumption goes astray. I did not read your other post before I wrote mine. Mosy likely, you wrote yours as I was writing mine. Well, I at least know it wasn't posted when I began to write mine. At any rate, your first post could have been much clearer regarding your desire for clarification. Perhaps you could have written "I would like the editors at FWW to clarify what they mean" in your first post.
Perhaps we should all be a bit more cautious on the boards. I certainly try to be, even if I fail from time to time.This is my personal signature.
I certainly have to agree about being more cautious, MK. I see much mis-information posted but fortunately most is corrected by someone in a reply. Again.. I am not literary gaint and barely literate for that matter.. but I assumed that the title of the thread:
Asa C... What were you thinking? would be viewed as perhaps there should be some clarification here to avoid a responsible source of WW info having a vague statement as it were be mis-interupted. I am sure there are some that did just that as I am still not truly aware of how the wording was meant to be received?
And for that matter no clarification as of yet as the article remains as was for those that have not seen this discussion to read. But.. as Sgain stated.. I'm just a dumb WW and have much to do still in the shop this evening.
Regards..
Sarge..
Matt & all,
I don't use a splitter or riving knife and I have no fear of kickback.Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Bandsaw?
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
Good thought, but no. I'm still talking table saw.Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
What procedure do you use to avoid kickback?
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
I bet he's talking about using a power feeder. These do generally eliminate kickback.
Most nights are crystal clear, but tonight it's like he's stuck between stations.
I hope he is but somehow I don't think so. His past posts have pretty much said he just uses his hands and a push stick. Back in January he said "All my accidents on the tablesaw involve kickback.". I was hoping he adopted a new procedure since then and not just the no brains no headache (what? me worry?) approach.
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
Did I really say that all my accidents on the tablesaw involve kickback? I hate to change my story if I did indeed say that, but I haven't had any real accidents on the tablesaw, save for one incident where I WAS using a splitter cutting a piece of case-hardened maple. I obviously didn't know it was case hardened until I started the rip. By the way, I use push blocks which I feel are much much better than push sticks.
I don't subscribe to this philosophy, but one woodworker I know feels that safety features only make the user more complacent.Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
I noted several disagreements regarding the interpretation of the grammar used in this article. The only issue is, to me, "could the statement be construed so as to be misleading?" That is, could it cause one to believe all danger is removed by use of a riving knife? The simple answer is "yes."I've been playing the role of sawdust maker for over three decades. Until recent, I've never ran with a splitter, antikickbacks or a blade cover. I just ran scared as hell. No close calls, just scares (I have to be careful, I have back trouble, there's yellow streak running up the middle of it when it comes to my table saw). One thing that has helped keep fingers and such intact is, I always thought those who relied on little push sticks ignorant or foolish, except in a few situations. I started using specialty push thingamajigs shortly after I started making sawdust. Similar to what has become more common today, they cover no less than ten inches of the length of the board [being cut] at a time. They even allowed me to make hundreds of 1/8" wide (or smaller) cuts without turning the product into projectiles. Having fingers near blades scare me to this day.Recently, I purchased an Excalibur over arm blade cover and a Merlin splitter (mine is an antique Unisaw (about four years old), so it doesn't enjoy the advantages of a riving knife). The splitter certainly does instill a sense of comfort, as does the blade cover (when I can use it). As such, I appreciate all the feed back to remind me that NOTHING is so fool proof that I cannot overcome it.
Unless my arms are classified as a power feeder, no.Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Don,
Common sense, knowledge & awareness, a good push block, properly dried wood, sometimes a short fence (thanks Sarge) and a big emergency off switch (which I thankfully haven't had to use yet. Also a properly aligned fence. Anticipating you questioning my "knowledge", I'd define it as, in this situation, understanding of what is safe and what is stupid to do. Eg. I don't tilt my blade towards the fence to cut a bevelled piece.Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Even properly dried wood can bind and kick back if the kerf closes behind the blade or the wood contacts the back of the blade. Even your young reflexes aren't fast enough to hit that big switch in time.
The short fence is a good idea but I wish you would make yourself a splitter and crown guard to go with it. You have a lot of talent and enthusiasm and it would be a shame to have your ability to do what you enjoy so much cut short.
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
Don,
From what I've read and heard, almost all, if not all accidents occur when the user is tired or distracted or using an unsafe technique. In my mind, guards are effective at preventing an injury in such a situation. If working smartly and safely, the guard is never needed. I also like to see the blade and where it is cutting. Sure the guards are clear, but they bend light and get scratched, etc, etc. Somehow I feel safer without one.
A riving knife/splitter does work to prevent the workpiece from binding on the blade, but personally the worst I have experienced lately is mild burning. I am aware of the benefits of these devices but currently don't place much value in them. Yes, I do value my ten fingers, but so far working smartly has paid off.
That being said, the next tablesaw I get will have a riving knife that I can leave on all the time. Maybe it'll be a Sawstop.
Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
I'm with you there Chris. Like you I do not fear kickback but I do fear and respect the machine, so I make sure that my head and hands are in the game every time I use the device. I have had kickback from my miter saw (not the work, but the cutting assembly) but never from the table saw.
Quality blade, Clean blade, proper fence alignment - my fence is ever so slightly angled away from the blade at the back side, firm and consistent contact between the work and the table when feeding.
I also believe that you have to develop a feel for each machine in the shop. If the machine doesn't sound or feel right then something likely needs adjusting. If you just keep on going you may have an undesirable result - burned wood, burned blade, overloaded motor, personal injury etc. Don
As an enthusiastic riving knife user I totally agree that neither it nor anything else could totally eliminate the threat of kickback. But I do think and feel that it greatly reduces the chances. It puts the risk of kickback under my control enought that I have the confidence to work safely. I am not saying that I am absent-minded when using a knife, but quite the opposite. For thoe who are safety oriented, there's nothing like the back side of the blade doing more than it's share of work to ruin your concentration!
Clearly Asa exaggerated the point, and you are right in mentioning that.
On thing about riving knives that just perked my brain is this: besides reducing the risk and severity of kickback, wouldn't they also directly reduce the depth of injuries? In my opinion, fingers are usually cut by being pulled BACK OVER the blade, so wouldn't the knife's shape lift up the fingers and limit those cuts to a rather shallow 1/8 to 1/4 of an inch? Pretty cool. I've never been injured by a riving knife saw, only by one without, so I can't measure my injury to be sure . . .
Brian
Brian, I'm curious as to how you could possibly get your fingers at the outfeed end of a table saw blade so that they could possibly be dragged back into it?
Dragging wood through a saw from the outfeed end is a very curious and unconventional method of ripping timber, and in my experience the fingers of the worker never pass over or besides a spinning blade. The hands should always be on the infeed side, and never get closer to the front of the blade than about 8- 12". Slainte.Richard Jones Furniture
yes, I was referring to an unsafe technique which some may do without thinking, toward the end of a cut or when handling short or awkward pieces. More 'wandering hands', not really 'pulling the workpiece through'. Don't worry, you won't find me doing it! I just thought the shape of the riving knife looked interesting in reference to this particular cause of TS injury.Brian
I have never used a splitter or a riving knife and almost never have kickback. I always assume that kickback will occur and stand to the side, use a pusher and a left-tilt saw. years ago, I did send a small projectile through a sheetrock wall, but as I was not in the line of fire, it was just another moment. It's experience and common sense that protects us in the shop. I would never depend on a company's word that some new device will protect me. After 50 years of woodworking, I have ten fingers, one small scar and one hairy moment to remember.
By the way, my father taught me years ago that if the saw blade starts to bind when being pinched during a rip, shove a screwdriver to separate the pieces and it solves the problem. It has never failed.
Saw safety is a big issue, and while Knifes and splitters (good ones) and guards and even Saw Stop all help none of them are perfect (and in SawStops case the break does not prevent kick back, so all saws are equally prone to this issue). Are they getting better yes. But it is something we in the hobby (and those in the business) need to keep a watch out for and make sure we do everything we can every time to keep it to a minimum. Something listing a safety devise as the end of that problem only makes people think they do not need to do anything to protect themselves as the tool will do it for you and down that road is danger.
Still if we all do what we can (and what we can afford to do) to minimize the risks we will all be better off. If that means you can afford a SawStop great, or if it means adding a splitter and a guard so be it, or if you are a tool maker it may mean redesigning your saw and adding knives and such. These things should not be discouraged. But at the same time we need to not over inflate the value of them. Anytime you are running a sharp blade in a saw their will be danger. Just try to keep you mind on what you are doing.
As for the comments about older folks, well that is one of the big reasons why I have been (as money allows) upgrading the wood shop. My father does more work in the shop then I do (by a lot) but he is getting older, (77) so anything that makes it safer is in my opinion a good thing.
Doug Meyer
I have a hole in the back of my shop 20' away from the TS blade line. I won't repair it as it is there as a reminder of what I mentioned earlier about the first thing I learned in HS Shop class on a TS. Keep the Lane Clear and I do just that. After I hit the kill switch I won't walk across the "line of fire" until after the blade quits spinning and for a definite reason.
Over 37 years now, I have had at least 5 side to side kick-backs but have not drawn blood on any fortunately. Two have been with a riving knive.. two without a splitter (early 70's when I was young and stupid) and one with a splitter. I have had numerous missle launchs to the rear as we mentioned as I rip an average of 100,000 feet of stock a year. But even though they are kickback I am not overly concerned as I adhere to KEEP THE LANE CLEAR.
All of the side to side kick-backs have come from sheet goods. I only use them for dust shields and drawer bottoms on chest and the occasinal utility job around the house. But.. after taking a pretty strong gut blow from a sheet I now cut them down with a circular to a much smaller working size I can take to the TS. And then I wear a thick leather apron as I do remember that gut blow I took.
You may go the rest of your life without a kickback not using a splitter.. then again you may get one today if you are in the shop often enough usnig your TS. I use a splitter.. a shield.. a spring-board.. short fence.. crown guard and never put my hands within 8" of the blade. I also don't fear kickback as I have protected myself as well as I can be protected with common sense and mechanical aids. I attempt to master the machine in lieu of it mastering me. :>)
Sarge..
Edited 9/5/2008 10:52 am ET by SARGEgrinder47
Shoving a screwdriver in the kerf to prevent the pinch would make me nervous (envisioning something happening, causing the screwdriver to fly across the room. Yikes.) I use the small plastic wedges that are sold to level furniture or whatever with. They're a couple inches long, about 1.25" wide, have ridges to make them stick where you put them.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
fg, I did just wonder, for perhaps 1/12 of a minute, how in the millisecond that's availabale between the beginning of the wood binding and the actual kickback occuring, an operator has the time to let go of the wood, go and find a screwdriver, then walk around to the back of the rip saw and jam said screwdriver into the pinched saw kerf.
Then I realised I'd entered some kind of dreamland and gave up on the daftness of the idea.
Here's a link to an old article I had a part in initiated by Barb Siddiqui about how she adapted her saw to use a in a more 'Euro' style along with some comments I made on using what are commonly described in north America as 'Euro style' saws kitted out with riving knives, crown guards, and what are misleadingly named 'short fences'.
Some people might find it useful, but having now read all the contributions to this thread and concluded there is some evidence of gross ignorance of the physical causes of kickback and steps available to reduce such cause and effect, I have my doubts about the usefulness of the article for some readers/contributors. Slainte.Richard Jones Furniture
Hi, Richard. I guess I've been lucky in that I've been able to tell when a piece of wood wants to tighten up on the blade, and I've quickly shut down the saw and placed the wedge in the kerf before starting up again. If that doesn't solve the problem, the band saw is the next option.
I like that article, and have had it bookmarked for some time. My only complaint is that the pictures, most especially the first one, are kinda hard for these eyes to see well. In the first picture, the L-shaped "half-fence" appears to end quite past the center of the blade.
I like the term "half-fence" better than "short fence" -- will try and use that term in the future.
The most dangerous kickback I've suffered was not while ripping wood, but rather when cutting an almost-square, medium-small piece of stock, and not handling it correctly. It lifted in back and spun over the blade, richocheted off my side all the way across the shop. Took me a couple days to find it, buried in the vertical lumber rack. Recollection is that I had used the dado blade earlier and fogotten to put the Merlin splitter back on. This is the kind of thing that can really mess the hand up if one does not let go, no?
View Image
View Imageforestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
That looks like the classic cross cut kickback when the wrong equipment is used to make that type of cut: table saw, long fence used as a length stop, no riving knife or splitter, no crown guard, and a good chance the blade was set fairly low-- the front right corner of the wood moved away from the fence and initiated the inevitable sequence of the wood climbing up as the rear rising teeth of the blade grabbed the board and the wood spinning up, back and skywards towards the operator.
I witnessed a couple of those mishaps when I lived in the US. One resulted in the wood whacking the guy in the chest, shock and perhaps wounded pride. The other required the girl take a trip to the hospital to repair severe lacerations to flesh, muscle and a couple of tendons in one of her hands-- and about eight weeks off work plus some permanent impairment in the most severely damaged hand, but no complete loss of fingers. Slainte.Richard Jones Furniture
I take wet wood or stock suspect of extreme tension to the BS at the first sign of excessive tension release. I raise the blade higher than manufacturers recommend as Richard mentioned as the front down-ward teeth help push that end down.
I un-loaded a new 5 HP TS I brought home from working at IWF last week after the rain went away from hurricane Fay. It comes with standard equipment which I consider in-sufficient for my own peace of mind. I spent several days "tricking it out" to my liking in the safety and dust department. Just used scrap for the most part with about $20 of plumbing parts from a Box Store.
The picture's are to show that I practice what I often preach as I finished about an hour ago. Excuse the darkness as the pictures were taken after mid-night. But.... she's ready to roll. Let the "big dawg eat"!
Sarge..
Oops.. that's my old Uni-saw... will post 2 picture's below.
Edited 9/6/2008 12:38 am ET by SARGEgrinder47
Good deal Sarge, I have no doubt you worked hard to aquire it. I also have no doubt you will make full use of the 5 hp. Enjoy!!
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
Those were my old Uni-saw, DG. My wife posted the two I took and put them in her file. We're both tired and I'm old which is a distinction she doesn't share. :>)
The new pics are in a post just under your post to me.
Good night all.. the ole man is tired on EST..
Sarge..
To be honest Sarge I did not even notice there were pics. My observations stand.... Old and tired here on PST too, good night to you sir....
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
Thanks D.G. ...
Sarge..
Nice work Sarge. You should patent that system! Looks like you didn't use the wider PS guard. Did you modify the SC one? Is the stop button easy to find? I see they've gone to the paddle switch on the smaller saws.
Jim
The paddle switch is on the 3 HP and under saws which are made in their China plant. The 5 HP and 7.5 HP Industrial saw are made in Taiwan by a very reputable company that only has 78 total employees. I will be posting a new thread on Monday (Steel City Ripper) with more detail as the saw is very well made and has extremely tight tolerances from stem to stern. Just as an example the arbor nut on this saw is around 3/4" thick as opposed to my Uni-saw which was around 1/4'.
The guard and shield are stock after I made modifications on the BS on the shield. 3 1/2" off the rear and a hole in top to mount a do-hickey I found in plumbing supply at the Box. I did some extensive modification to it and it fit right down inside the plastic shield. The stock guard allows me to run the half fence up closer to get a 5/8" rip without removing the guard.
But.. a PS "wide-mouth" shield sits under my assembly table ready to be modified. You can't rip as close to the blade with it on.. but it does catch more dust on wider rips. The good news is I took off the fixed pin that holds the stock shield on the splitter and replaced with a clevis pin and a cotter pin to secure. A quick pull of the cotter pin gets the shield off in about 5 seconds and about 10 seconds to replace it. I will use basically the same set-up for the "wide-mouth" as I will alternate between the two width shields depending on need.
Other good news is the splitter releases it's 3 secure bolts in about 10 seconds as I took out the standard 5/16" bolts (wrench secured) and replaced with spring loaded cam levers. A quarter turn of each lever releases which takes about 10 seconds to remove the entire splitter. The dust port in the top is modified for quick release also and I added a home-made crown guard made of hard-wood to the splitter front.
So.. many other modifications have been added other than that to save me time. I will go more into detail with the thread I intend to do on Monday..
Sarge..
Edited 9/6/2008 11:14 am ET by SARGEgrinder47
Thanks Sarge -- I'll look forward to the new thread. I don't know why SC doesn't just add a dustport to all of its guards. DC is one of its few weak points.
Jim
I was tired.. :>)
Here they are...
Great work on a fine TS, brother!
A few minor details and I'll try to get some better pictures of the massive inside casting. This thing is a beast of a machine with no bells or whistles but a great and power-ful saw. With a few modifications it has become a great and power-ful saw with safety features and dust control.
Just finished a 4 piece bed-room saw with the old Uni-saw I sold for this one. This saw gets the call on Monday as we start production in the family room.
Again... let the "big dawg eat"...
Sarge..
Greetings Sarge:I see from your photos that you are using the Grip Rite magnetic boards. I saw them being demonstrated at IWF and picked up a pair.They are really, really useful. One of the best things I have found. I have used on the shaper, bandsaw and jointer (to hold the face to the fence when jointing the edge). Very quick and easy to set up too.Hastings
What you saw was a Grip Tite I modified and put one of my home-made spring-boards on. I use it as a portable as I did at the IWF Show where I was working with stock table-saws. It came in very handy as I really prefer support left of blade and the stock saws do not have the add-on miter on the end of the left table I add to firmly anchor my large spring-boards.
They are handy indeed.. especially on a BS, jointer, etc. But on the TS I do prefer the larger spring-board as you will see latter today on my new 5 HP TS I picked up at IWF. I will be doing a thread in Power Tools on the Steel City Ripper. :>) My larger version is quick.. extremely stable as it supports more surface on the stock and no chance of the magnet scratching the cast iron on removal.
Sarge..
I learned a major lesson from that incident. Started with being tired and went downhill from there, yielding bad judgment and poor practices. A physics-instigated "dope-slap" to make me pay attention from there on out.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
FG, You are very fortunate to have avoided serious injury when that piece went flying! You should either nail the piece or your photos near your TS as a remembrance . . .
FG,
Your last sentance gives me pause. "If you don't let go..." Most people don't know that they won't have any choice about whether to let go or not, and hopefully won't find out. By the time you notice that letting go would be a good idea, your fingers will be on the floor, unless you're lucky. The mere contact of your skin against a piece of wood will drag your hand wherever the wood goes, before you are really aware of it. I know you are an advocate of good safety practices, from your posts, but very few people understand how instantanious these events are. You have no chance to alter the outcome of an accident event after it has started, and can only prevent it or regret it after.
"By the way, my father taught me years ago that if the saw blade starts to bind when being pinched during a rip, shove a screwdriver to separate the pieces and it solves the problem. It has never failed."I agree with forestgirl and would never use a screwdriver. I was taught by my father to use wooden wedges. There is a danger in that too, because to put them in you reach over the spinning blade. That is the moment when that board will kick back and possibly bite off a few fingers. The short fence and riving knife/splitter or a second person to stuff those wooden wedges is a better practice.All the best.
In sharp contrast to what FWW has done, the current issue of PW has an exhaustive discussion of tablesaw safety by Marc Adams which would be much more useful to a novice. If I have a criticism of it, it is his assumption that there is only one type of riving knife, the short type that sits below the blade without being attached to a guard. (He advocates an aftermarket guard.) As I've pointed out before, most North American makers provide a tall riving knife with guard and pawls attached. It may look like a splitter, but it's a riving knife: it moves up and down with the blade and maintains a constant distance from it; and it provides protection from two kinds of kickback. You can remove or replace it in seconds. Every magazine and blog seems to make this same wrong assumption about riving knives. I suppose it stems from the notion that riving knives are desirable because you never have to take them off. You rarely have to take the short knife off, it's true, but if you use it all the time then you should add an aftermarket guard with crown. And it's easier to attach a crown to the tall knife.
If these guys would only read Knots they'd have learned this long ago from Richard Jones and Sarge. Perhaps they're too busy writing to read.
Jim
QC, the instant I feel wood binding, I switch the table saw OFF. Then I go around to the back, insert the wedge, come back to the front and slip the stock a little toward myself, and holding it down carefully turn the saw back on. I never, ever would reach over the spinning blade for such an operation (or any other, really). forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
TS kickback is a serious problem. The kerf slitter or riving knife addresses only a part of this problem. As a rip cut divides a board, internal stress is relieved. This could cause the board to pinch the blade, possibly resulting in a kick back. The slitter might be effective in this situation. If you were trimming the edge of a board, it probably would not.
I have found that kickbacks are most often caused by misalignment issues between the fence and the saw blade. It is very important that the leading edge of the blade is closer to the fence than the back edge of the blade. There only has to be a small amount of clearance on the back side. (a couple of thousandths) As the board travels thru the saw blade, the leading edge creates a saw kerf for the back edge of the blade to follow thru. It seems most kickbacks are caused by this back edge being pinched by the fence. To fully address this problem, we use fences that are secured in the front and rear positions. A t-square fence without any rear hold down has enough flex that as you push your board against the fence it moves away from the saw blade (maybe only a couple of thousandths). After the cut is completed and your pressure is naturally reduced the fence pushes the board back into the blade, causing kick back.
Another factor in kick back may be dull saw blades. They create excessive heat which causes the moisture and resins in the wood to boil and the wood to shrink pinching the blade. Use sharp blades.
"It seems most kickbacks are caused by this back edge being pinched by the fence. To fully address this problem, we use fences that are secured in the front and rear positions. A t-square fence without any rear hold down has enough flex that as you push your board against the fence it moves away from the saw blade (maybe only a couple of thousandths). After the cut is completed and your pressure is naturally reduced the fence pushes the board back into the blade, causing kick back"... Lixer
***
Yep.... that's why I use a half fence clamped on the face of my full fence and have been preaching safety for about 6 years now after having been instructed by Sgain Dubh (Richard Jones) that is posting in this thread. For those that use a full fence (which is most here in the U.S.), the slight toe-out is important. Toe-in is a no-no for the reason you stated.. you help instigate rear rising tooth pinch especially in reaction wood when stress is relieved.
Sarge..
Edited 9/6/2008 10:50 am ET by SARGEgrinder47
Hi, all--
I'm the Asa in question. I haven't read every post in this thread, and like you I've heard everyone back away from saying riving knives eliminate kickback, but if what we are talking about is true kickback, where the board gets up onto the back teeth, then I stand by my statement.
With a riving knife adjusted correctly (true, I didn't make that caveat in my article), it will hug the back of the blade, and with the knife in the saw kerf it is a physical barrier against the board moving onto the back teeth.
Now of course there is a different thing, which Kelly Mehler, others, and I call pushback, where a cutoff piece is pushed back along the rip fence, but in this case the force of the teeth rubbing on it is somewhat indirect, and these pieces don't become missiles unless they are grabbed and lifted by the back teeth. There should be a push stick on that piece, pushing it past the blade and knife (true, I didn't say that either).
Where I did goof, however, is in forgetting about the dado set. It's true that the riving knive must come off for dadoing. Big goof on my part. My only excuse is that I was writing at the IWF in a blog, on deadline, which is no excuse really.
If someone can come up with a way true kickback can happen with a riving knife hugging the back of the blade, I'll take back my other statement too!
I'm not buying the rip fence thing: If it is misadjusted, then the board will just wedge against the riving knife and not move forward at all.
OK, have at me. I've got my thickest skin on today.
--Asa
"If someone can come up with a way true kickback can happen with a riving knife hugging the back of the blade, I'll take back my other statement too"!... Asa
A riving knife (or splitter for that matter) cannot be wider than the saw blade kerf or tooth. A riving knife cannot be so close to the blade that it might touch so there is a gap of usually around 1/16" to 1/8" between the rear rising teeth and the knife.
Reaction wood can close to the point that it touches the rear rising teeth because the knife or splitter has to be narrower to clear the kerf. The thickness of the riving knife will vary from manufacturer to manufacturer but the average variance is around .020 to .030 narrower than a full kerf blade. Not much variance... but enough! Extreme reaction stock can close on the dangerous rear rising teeth allowed by the variance.
You may not buy the fact that a fence towed in or rebound off the trailing end of extreme reaction wood can push the stock into the rear of the knife or splitter but I certainly do. Have you ever seen a riving knife or splitter which is anywhere between 11 - 14 guage that wouldn't flex? They all do and if the push from tow-in or rebound off the trailing end of a long fence is extreme.. it can flex the knife or splitter and allow the stocki to touch the rear rising teeth also.
BTW... all riving knives don't sit below the blade and that's a fact..
Regards...
Sarge..
Edited 9/6/2008 10:19 pm ET by SARGEgrinder47
Sarge,
Why couldn't the splitter/riving knife be 0.02" wider than the kerf? As long as the leading edge is bevelled as is the case, the elasticity in the wood would allow the stock to get around the splitter/riving knife.Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Because if it were .002 wider it would not allow the stock to go farther than the splitter or riving knife. And if it did.. you would have to create more force to get it through which could lead to twist which could lead to kickback without a detailed explanation.
Elasticity in wood... just how much elasticity is there in oak.. maple.. etc. etc.. Not a lot and in some cases none when you are shoving 5/4 to 12/4 hardwood. Even so with softwood.
Have a good day Chris...
Sarge..
Welcome back Asa;
Is it not possible for the kerf to close and pinch on the plate of the blade forward of the teeth and be lifted and kicked back by the rising teeth before reaching the knife?
Edit: You beat me to it Sarge, I knew I should'nt have gone to stir dinner and leave my reply unposted!
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
Edited 9/6/2008 10:18 pm by dgreen
Dgreen--
It is a good question. I suppose almost anything is possible, but I've never seen it happen, not even close. Remember that the riving knife should be just a fraction of an inch behind the blade. I can't imagine a board closing that quickly and with that much force...
Can I guarantee that nothing bad will ever happen with a riving knife in place? I guess not. But with one in place, I have no fear of kickback.
--Asa
"I can't imagine a board closing that quickly and with that much force..."
Asa, I have experienced that kind of force pinching on the rear of the blade and riving knife due to stress release in the board. So much force was released, on more than one occasion that I've experienced, that the only thing that prevented the kickback occuring was the crown guard mounted to the top of the riving knife and the riving knife mounting bolts that held the knife in place. I'm talking of the other non-dagger style riving knife that is mounted to some machines, and not the dagger style illustrated in your blog. The dagger style of riving knife would not have prevented the near kickback incidents I described earlier in this paragraph.
I've experienced such great force when planks close up after the cut that the only way to relase the pinched plank from the stalled machine, riving knife and the saw blade was with lump hammers and steel wedges. That kind of force from stress release in wood I admit is rare, but it does exist in the odd plank. In all my thirty odd years of using typical European type saws where the riving knife, crown guard and short set fence has been standard kit and practice for decades, those rare planks that pinch that powerfully have caused me the most buttock clenching moments, ha, ha.
Stress release in planks is a funny and unpredictable thing. Sometimes it is apparent that a board is stressed as soon as the cut starts and it pinches on the saw blade-- you can stop the cut and deal with the plank another way. In other planks stress and pinching, or conversely opening up of the kerf, doesn't reveal itself until a good way into the cut, and even sometimes it shows up only in the last 300 or 400 mm of the rip cut. In each case the plank might be anything from as little as 1 metre (3 ft) or less in length up to 4 or 5 metres long. Slainte.Richard Jones Furniture
"That kind of force from stress release in wood I admit is rare, but it does exist in the odd plank."
Have you noticed any pattern in which boards tend to do this? Are they wildly figured? Super hard, super dense exotics? Boards with the pith included?Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Have you noticed any pattern in which boards tend to do this? Are they wildly figured? Super hard, super dense exotics? Boards with the pith included?
I don't want to answer for Richard, but in my experience it has little to do with the type of wood, but more to do with the way it was dried, and where it came from on the tree (such as reaction/compression wood from a limb).
Lee
That's about it mapleman. One element that is fairly consistent is the board thickness. The thicker the board in my experience, the more likely it is to show symptoms of stress, eg, casehardening, reverse case hardening, core collapse or honeycombing. This applies morso to kiln dried thick stuff than air-dried, although the latter too can show similar symptoms. By thicker I mean 3" (12/4) thick and above.
Another element I've found fairly consistent is species. It seems to occur more often in, for example, hard maple than many other species.
On the whole, apart from those circumstances mentioned that I've experienced, which is admittedly unscientific and unquantified, finding stress in a pile of planks is rather random. For example, 98% of a pile of 2" thick kilned oak (red, white, or European) is fine, but then you'll come a cross 2% that are case hardened or something, and that pile probably all came out of the same kiln on the same day. Slainte. Richard Jones Furniture
Yeah... but he didn't read post 100 I made to him as it is un-read. He didn't read some of the earlier post either where I mentioned I have had two kick-backs with a riving knife on. I suppose I don't have the clout you guys do. ha.. ha... ha..ha..ha..
Sarge..
One source of irritation for me is that you don't show or mention the tall riving knife with pawls and a guard attached which most manufacturers provide as the main safeguard. That riving knife will safeguard against backward or upward kickback by whatever name you want to call it. The short riving knife sitting just below the blade is intended for non-through cuts (or for those who use separate aftermarket guards). The manual provided by SC tells you always to use the guard. You're not alone in always and only showing the short knife -- every ww mag seems to do so. I guess once an idea takes root it's difficult to change the public perception. The earliest accounts touted the riving knife as a saviour for all those idiots who are too lazy to use a guard/splitter, because you never have to take it off. That just isn't true. What manufacturers have done is to make removing either knife fast and easy. You won't find a manufacturer making exaggerated claims for a short riving knife -- they don't want to be sued by the first bonehead who accepts the myth.
Jim
Good point, Jim--
I tend not to focus on the taller riving knife because it will have to come off the saw from time to time. Maybe other editors do the same. It is a judgement call, but my guess is that if people use the shorter, shark-fin knife, they will be more likely to keep a splitter on the saw. They've proven they won't tolerate something that has to come on and off the saw all the time.
But you are right that the safest approach is to keep the taller guard on the saw as much as possible, equipped with its blade cover.
Where I disagree with you is on those "anti-kickback" pawls. They do no such thing. If anything they stop pushback (see my earlier post). But they too often get in the way of your push stick, which is a indispensable piece of safety equipment.
--Asa
I agree about the pawls. Apart from anything else they're too far behind the blade, and can make changing knives awkward. But they're better than nothing. I'm replacing mine with a home made crown guard sitting over the blade. It's not too difficult an upgrade, but I wonder why manufacturers don't just do it. Because the riving knife rides up and down with the blade, the guard on these saws has to swivel, and I'm not sure that the guard alone whould hold down a rocketing piece of wood.
I actually have and use a riving-knife saw, and I find I rarely have to remove the tall knife with guard. You can leave it in place for ripping and crosscutting. I replace it with the short knife only when cutting small and narrow stock, for which I don't trust push sticks. I use GRRRippers for these. For me at leaast, non-through cuts that don't involve a dado set are rare. Changing a knife really does take less than a minute.
Jim
Edited. Are you saying that because "pushback" is technically not the same thing as Kickback that it may therefore safely be ignored? I think what many disliked about the blog was that it presented a short riving knife as the complete answer to a problem. Use this and you won't have to worry about kickback, won't need to worry about the missing guard. But it's a partial cure for part of a problem. One picture like that in an influential mag. has much more influence on the novices you are trying to attract than any amount of advice from old goats like me.
BTW, thanks for facing the somewhat raucous music on this thread.
Edited 9/7/2008 11:54 am ET by Jimurock
AsaC
I hate to disagree with you but your so called bush back took a piece of wood and slammed it into a door about 9' away from the table saw hard enough to put a hole in the 1/4 hardboard the door was made from and dent into the 3/4 foam inside. Not sure how much force that was, but I figure if I had been in the way it would have speared me a good one. And not this was not a true kick back (using your terms) as it never climbed up the blade and it flew flat to the table. FYI it was a piece of cherry about 1" by 3/4 or so (yeah I know I should have been more careful, but I was young and dumb)
Doug M
Hey, Doug--
I've heard of that happening but never seen it. Were you using a push stick between the rip fence and the blade?
--Asa
Yes I was a home make job, but I am still not sure how it happened as it happened WAY to fast to understand with out slowmotion replay. It was the second scariest thing to ever happen to me with a table saw (the first was when the saw ate a zero clearance insert.
Doug M
"I've heard of that happening but never seen it. Were you using a push stick between the rip fence and the blade"?
--Asa to Doug...
You didn't read post #100 to you from me explaining how the stock can close on the blade? But you answered post #101 to D. Green! And if you had read earlier post as you mention you didn't read all.. you would have read where I have had two kick-backs with a riving knife on my TS. Richard Jones told you that he has had it happen on numerous occasions as I knew he would when he read your comments.
And you would have read that I have had a narrow off-cut launch rear-ward about 18 feet and penetrate a sheet rock wall and almost to through the opposite side. And I was using a push stick as I have used one for 37 years. I don't put my hand closer than 8" to a blade. You can also get a launch off the opposite side of the cut side but a good feather-board or spring-board with proper tension will stop or slow it down.
A feather left or spring-board left will also keep the stock from twisting left of blade on a kick-back. A crown guard will also stop it from launching up on a kick-back as Richard Jones pointed out to you. It is rare to get kick-back in the manner we described as extreme reaction wood is not that common. But... for those of us that spend much time actually ripping on a TS we know it can and most likely have had it happen. And if you don't know what a spring-board is.. here's a picture of one I just made from scrap.
Regards...
Sarge..
Hi, Sarge--
Nice to meet you at IWF (That was you at the Steel City booth, right?). Featherboards and springboards are great things.
Are you sure these kickbacks happened with true riving knives in place, the European kind that always stay within 1/8 or so of the back of the blade no matter what? I've seen reaction wood pinch a blade behind a splitter but never a riving knife. Perhaps, like you say, I just haven't logged enough hours ripping.
Maybe the best advice we can give anyone is to do their ripping on the bandsaw whenever possible....
All right, I'll back away from the discussion now, but I'll be listening to see if anyone can convince me that kickback is a real danger with a true riving knife in place, the saw properly set up, and a push stick in use (I recommend the long shark-fin type that presses down on the workpiece far forward of your hand.).
Asa, out.
Did you miss Richard Jones reply to you?
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
I am absolutely positive it was a European riving knife Asa. I had a TS with Euro riving knife for almost 6 years before I sold it. Trust me Asa... I absolutely... positively know the difference between a true riving knife and a splitter. For that matter I have been preaching the difference for about 5 years on FWW forum and elsewhere. I can't even imagine how many times I have explained the difference between them on this site alone.
If you prefer I will do it again for just for you with all the confidence of someone that has used splitters for 31 years and a riving knives for 6 years. And as D.Green just pointed out in the post just after yours... you have obviously dis-regarded the post to you from Richard Jones who apprenticed in Europe.. ran a successful WW business in Houston for yours.. has written numerous articles that are printed in WW mags including yours.. and now is teaching WW at a college in England. Richard has experienced it many more times than I.
Is Richard J. and all of us who have experienced kick-back from tension wood with a riving knife in use telling lies? I don't think so... but you are choosing to ignore what we are trying to tell you. We are not trying to smear egg on your face... simply understand you are wrong about several things you contend.
There is far more honor in being wrong and willing to admit it than being wrong and trying to sweep it under a rug as you appear to be doing? And especially in this case where wrong information can easily get into the hands of entry levels that believe if a WW mag wrote it... it must be so. In this case it is wrong and potentially dangerous to anyone that might accept it as the truth and is simply not the truth!
And yes that was me in the Steel City booth at IWF demonstrating (not selling) table saws and bandsaws. And I probably didn't get there because they knew I didn't know the difference in a splitter and a true riving knife among other things.
Regards...
Sarge..
Edited 9/7/2008 5:37 pm ET by SARGEgrinder47
I suspect asa read the message sarge. I didn't really feel it needed a response. I'd guess he knows I've been around European style saws for longer, probably, than almost anyone else that hangs around here so I'm likely to have decent practical experience and insight on how they perform.
Anyway, I appreciate the point he made earlier where he stated he created the text for the blog thing quickly at the IWF; it's all too easy to write something and for it to get misinterpreted in that circumstance. That happens to me sometimes, and I'm talking about text I create where there is no time pressure or deadline to meet, and there's plenty of time to consider how a reader will take the words-- there's almost always someone that will see a different interpretation. Slainte.Richard Jones Furniture
Hi, Richard--
Thanks for the support. You always operate from the assumption that the editors are well-meaning guys. As it turns out, we are. Of course, I welcome the sharp attention of all of the Knots regulars. Usually everyone walks away better informed, including me.
Slainte.
--Asa
Richard & Sarge,Perhaps we can all agree, though, that a riving knife will greatly reduce the chance of a kickback.....? Just get the feather boards and hold-downs too if possibility of kickback is to be reduced to near-zero. :-)******If one uses both a feather board (to keep the plank agin the fence) and hold-downs (to keep the plank firmly on the table) a pinched board will sometimes still cut. The back teeth are now slightly recutting the (pinched) kerf that the front teeth first cut. The riving knife keeps the (trying to close) kerf open and in line with the blade.If the reaction wood is just a "spot" in the plank and not continuous, the "back teeth cut" is sometimes sufficient to allow the rip to continue. Sometimes this happens with a plank having a big swirly knot-spot in it. But if there is more reaction wood in the plank, even the "second-cut" kerf will pinch on the riving knife and it becomes harder and harder (eventually impossible) to keep the plank moving down the fence.Those holdowns do prevent the back teeth from raising the pinched-kerf plank off the table (i.e. prevent kickback). Nevertheless, unless there is just that one tight spot in the plank, it's as well to stop trying to rip the plank when the pushing gets harder, rather than wholly impossible. It's a nasty plank and must be done away with.If such a plank is sucessfully ripped, it is unlikely to end up with dead straight edges. However, I have re-ripped a millimetre or two from the slightly bent edges of such planks and eventually got two straight edges. Of course, one then has to worry about how long they will stay straight; indeed, whether the board will twist, etc.. That reaction wood or big knot is still in there waaiting to cause trouble. These days I abandon such planks early on in the process (or cut out the knot) as they are sure to lead to a wonk in the piece eventually. One lives and learns.Lataxe, who would really like a power feeder for his TS
Edited 9/8/2008 9:07 am ET by Lataxe
Totally agree about riving knives.. crowns.. feathers.. etc. Laxtaxe. And yes I have encountered pockets of resistance that sometimes are only momentary and will allow you through. Your theory of re-cut may be why is does allow you though... I simply can't say.
But.. if the resistance increases significantly... I stop feeding... hit the panic switch with my knee and wait until the blade quits spinning while keeping a firm grasp with hands or push stick depending on how far the stock has been feed through before the extreme resistance was meet. At that point I simply take it to the band-saw and rip it.
I've had some reaction wood close so abruptly that it bound on the RK or splitter with such force that I had to stop the saw... remove the crown guard and slide it up the RK or splitter to get if off. With that type stock I simply cull it and it goes to the trash bin as I deem it too un-stable to use in a finish piece. That kind of stress is not going away and will raise it's ugly head if you insist on using it in a finished product.
Back to the shop for me as a few details left on tricking out my new TS..
Sarge..
Lataxe, it is true that you can sometimes simply 'blast through' a bit of pinching and, believe it or not, I find the more powerful the saw the better it copes with that. I'm not suggesting that it's good or safe practice, but 5, 7, 10 HP saws do just keep ploughing through whereas small saws, 5 HP and below, tend to bind up and the piece of wood comes back at you.
I've never had much time for hold downs and feather boards on a saw, certainly not around rough sawn stock that is warped in various ways. They are alright for machined stock on spindle moulders and the like, but those devices can't cope with the dimensional variations and warp in rough stock. The best control I know for sawing rough stock is a heavy duty power feeder with a large ability in the rollers to handle rough material, but that sort of kit isn't available to a lot of people. Slainte.Richard Jones Furniture
>rough sawn stock that is warped in various ways<Trying to remember the last time I dimensioned rough sawn, warped stock on my tablesaw,....Lemme see,...oh yeah,....now I remember,...Never.The last time I got a chunk of walnut that had been air-drying for about 35 years (damn I wish I had some more of that!), that still looked like a part of a tree, it made a visit to the bandsaw first.
Yeah, me too. The table saw is definitely not the first stop for taming truely rough stock (I don't count S2S as really rough). My band saw, planes/electric planer, jointer/electric jointer would see the wood first.
Ed and Samson, it's common practice to rough dimension rough stock on a table saw, or at least it is in all the workshops I've worked in. I've been doing it all my working life. Every now and then I'll put a piece through the bandsaw, but at a guess probably north of 95% gets ripped to oversize width on the rip saw.
I guess you don't want to hear how we quite commonly make the first rip of waney edged boards freehand to a snapped chalk line or pencil line drawn against a straight edge? That's something you can do with a big saw, 18" or 20" diameter blade, riving knife and crown guard that I probably wouldn't attempt on a 3 or 5 HP Delta cabinet saw because small machines of that pattern just don't have the guts nor the safety equipment for that kind of work. Slainte.Richard Jones Furniture
How do you define rough? Is S2S rough to you? Why would you be addressing width first in any stock that had no relatively flat face. I suppose it might make sense if you had a severe cup, but that seems like it calls out for the bandsaw or the circular saw - i.e., a rip down the crown of a cup.
Wane edges are easily taken care of with a carrier board - usually plywood. Then you can use the fence and get a perfect edge on the first pass. Admittedly a bit more work.
Samson,There are many ways to make long, thin rectangles from slices of tree.... but I admit that I wouldn't have considered using a TS in the first step or two. The large bandsaw is a handy beast for cutting off waney or other woggly edges, especialy if the board is a bit cupped. I like the 1.5 tpi hook tooth blade for this, as it eats anything. One may do this freehand in complete safety, using a snapped-chalk line or other marked reference on the plank, as Richard mentions. Shurely a wonky plank on the TS table is asking for trouble, as the kerf needs to stay in line with the blade at all times.Alternatively, a hand-held electric planer set on "deep cut" can quickly take off lumps and bumps from one side of a slice of tree that is already flat, providing ####straight enough edge to go down a TS fence. Many rough-sawn planks out of the air-dried pile do in fact come out flat; or with slight, even cup (cut cup-side down on the TS); or only a slight bow (cut concave side up on the TS).Sometimes one must get rid of the excess width of a large waney-edged tree-slice with BS, to allow the board to be planed flat on the planer/thicknesser, as one has only 10 inches width capacity.When there is a nice flat side to go on the table and a nice straight edge to go on the fence then the TS comes into it's own. Once these reference faces are trued up, the TS is a lot faster than the BS at plank-slicing. It's also a lot faster than the P/T at cutting straight, square, parallel edges to obtain a required width-of-plank.
Edited 9/8/2008 5:32 pm ET by Lataxe
So ... you're agreeing with me, right?
Samson,Yes,I agree with you; but can't help elaborating at great length as my little brain whirrs noisily. :-)Lataxe
S2S as I recall from my days running my furniture business in the US is surfaced and squared on two adjacent edges. In other words most pieces are reasonably straight and square, or at least generally not too bad. Rough is rough sawn as it comes straight out of the kiln or air dried stack without any additional sawing or planing since the stuff was planked up from the log using a bandsaw mill, insert tooth circular saw, chainsaw mill, etc.
There are all sorts of ways to deal with rough sawn planks and ripping to a generous width on a rip saw is a common or normal approach along with cutting to a generous length on a cross cut saw prior to surface planing (jointing in US parlance), edging and thicknessing (planing in US parlance).
Let's say, for example that I want three pieces out of a 2" (8/4) thick board to finish at precisely 1-5/8" X 1-5/8". To achieve this in a wide enough plank that is not badly bowed, in winding, bent or cupped I might rip one piece that is roughly 5-1/4" wide. I'll flatten the wide face and straighten one or both edges. Next the the board is ripped to a bit over 1-5/8" from the trued edge(s) followed by straightening the sawn edge of the offcut on the surface planer again. This edge is used to rip the next generous 1-5/8" piece, and so on until three bits are produced a fat 1-5/8" in the width. If there is a need you can rip the last so far untouched face of the three bits produced to this fat 1-5/8".
The last job is to thickness to the finished 1-5/8" dimension on the sawn faces and edges in the thicknesser; a thicknesser with a sectional feed roller allows you feed all three pieces simultaneously with pretty good safety, ie, without the likelihood of kickback because sectional feed rollers can cope with material of different thicknesses which thicknessers with solid rollers that can't.
An alternative approach would be to rip three individual pieces to 1-7/8" or 2" widths which costs you nearly 6-1/2" in plank width. It's likely to be a bit more wasteful of the stock, but for badly warped pieces this may be necessary.
I don't see much advantage in a carrier board to deal with waney edges on a rip saw. Snapping a chalk line and freehanding the wood through also works-- if you know what you're doing. I'd guess it takes between quarter and a half the time to do it that way over a carrier board set up, and time is money, of course. However, to do this remember I am talking about using European style rip saws with riving knives and crown guards fitted, and I mean big saws, 5HP plus, and better still with 7, 10 or 12 HP. I wouldn't do it on the small US style cabinet saws, eg a 3 HP Delta Unisaw-- too puny, and the standard guarding on that specific machine is, in my opinion, inadequate for the job anyway and, in the US, usually missing entirely-- you're safer using the carrier board with hold downs and a runner for the groove in the table top.
I think what may be causing you some difficulties grasping how I work a table saw is probaly cultural. I'm European, I use European type saws, and I've been using this type of saw to make money as a woodworker all my working life. Big three phase European style saws, the type I've used in nearly all the woodworking businesses I've worked in are quite different in the way they perform to the smaller north American style cabinet saws.
Now that riving knives are belatedly making a reappearance on US saws after something like a 70 or 80 year absence I suspect that American users will begin to notice the differences between this saw type and the more familiar cabinet saws and their missing splitters and blade guards. This could also lead to some different approaches to rip sawing by north American users as they become familiar with the alternative saw configuration of riving knife and, possibly attached crown guard. I wouldn't be surprised for example for north American users to start realising that the long full length rip fence is really a pig of a fence for ripping wood; they might even begin to notice that the short set fence has significant advantages for this kind of work. Once they notice that this is actually the case, then perhaps they'll start using sawing techniques that we in Europe have been using for several decades. Slainte.
Richard Jones Furniture
Edited 9/8/2008 8:10 pm by SgianDubh
The Delta Unifence slides backwards to make a short fence.
http://www.amazon.com/Delta-U30-30-Inch-Table-Unifence/dp/B0007SXH32
I never understood why people preferred the Biesmeyer fence over this one.
I like my Unifence too, but when I need to make a bevel cut with my left-tilt saw, reversing the fence is a little bothersome. Not a lot of work, but there's none involves with the Biesemeyer. Also, the Biesemeyer is easier to build jigs for (tennoning jigs, etc.)Chris @ http://www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Richard,I tend to cut only already-dressed (or partially-dressed) planks on the TS. (That is, planks that present a flat face to the TS table. The hold-downs are to keep the flat downward-facing side of the plank on the table, not to keep warped planks from leaping off the TS as they wobble through the blade.My theory (wrought from a combination of experience, intuition and 6th form mechanics) is that a hold-down serves primarily to keep the plank flat on the table, not to keep it from leaping up if caught by the rear ascending teeth of the sawblade. The hold-downs mean that the ascending rear teeth cut the plank if it nips-up, rather than pushing it up that small amout off the table that would allow it to tilt, at which point the ascending blade digs in and throws the plank up (kickback). So, the hold-downs only need to keep the plank flat on the table; they don't need to have the capacity to hold 3 - 5HP of force transferred from the teeth to the plank and converted into velocity. The teeth never get the chance to dig into the plank and kick it back - they merely cut a bit more into the nipped-up kerf.Lataxe, kick-back theorist
And I suspect that you are correct about deadlines... as the IWF Show is huge (3 buildings of over 200,000 sq. ft. each) and difficult to cover due to the fact about all machine vendors from the World are represented in force.
I helped assemble machines 3 days before the Show and demonstrated them for 5 days during. You stay extremely busy almost every minute just in one booth. Trying to cover all the offerings would be an enormous task with a deadline as each magazine is trying to out-scoop the other and be first. So... that makes sense to me.
Thanks for your in-put in helping resolve clarification of the issue as was stated...
Sarge..
Hi, Sarge--
You are right that I didn't read every post. But after reading what you, Richard Jones, Dgreen, and others have said, I have to concede that it is possible for severe reaction wood to pinch so hard that it starts toeing in as soon as it clears the front teeth, and immediately kicks back when it hits the back teeth but before it gets to the riving knife.
I've never seen that happen, but enough of you have come forward to say it has. It makes sense theoretically too.
So I'll change my statement in that blog. I'll back off from the "no fear" to something like "far less fear."
Chalk one up for the Knots crowd!
--Asa
Thank you sir as the wording.. "no fear" as opposed to "far less fear" clearly denotes to the reader there is still a possibly of and to not let their guard down. As we stated it is rare but can happen. I have only had that incident happen twice in 37 years. It might never happen again but it could this morning as I return to my shop after having to wait for a new TS after I sold mine.
The good news for me is I expect kickback to happen at some point as I rip many linear feet of stock a year. But.. I have taken every precaution I can to cover every exit that a kickback can go with mechanical aids and by Keeping the Lane Clear while the blade is spinning. So.... I operate with "far less fear" of kickback but understand that it can and probably will happen as I have much exposure time.
Thank you again changing your stance after listening to the audience who have experienced what we are discussing. That was all that was really required from the beginning.
Regards...
Sarge..
Edited 9/8/2008 11:02 am ET by SARGEgrinder47
So, do they make an after-market riving knife for my 30 YO Unisaw.
Nope.. the Uni-saw has been the same design since 1937 when it came out and just about all American saws were designed on it's principle. The trunnions are not designed in a way that a riving knife can be attached period.
But.. Lee Styrone makes the excellent Shark guard for many American saws and he definitely has one for your Uni-saw. Quick release with a crown of sorts and very good over-head dust control. If you are interested just Google shark guard and the site should come up. But.. he works a day job and the guard is popular enough he quotes a 2 month wait after you order. But... all that use them contend it worth the wait.
Regards...
Sarge..
This forum post is now archived. Commenting has been disabled