The recent thread on ripping with the Powermatic has me wondering what exactly is going to be required as a riving knife from North American companies when the legislation kicks in. As far as I know, the PM has a knife attached to pawls and a guard, and differs from a conventional splitter only in moving up and down with the blade. General offers the same, along with one “European – style” riving knife that stays below the top of the blade and has no attachments. Steel City has what PM has, though it calls it a splitter, and gives 2 separate European – style riving knives to accommodate different blade thicknesses. I have the SC, and expect the guard-splitter will languish in a drawer. Does anyone know what is going to be the mimimum requirement? And can anyone who has used riving knives explain why the type with guard and pawls offers any improvement over the European type?
Jim
Replies
If it moves up and down keeping the same distance from the back teeth of the blade and also tilts with it.. it's a riving knife. Regardless of where it's made.
All European riving knives don't sit below the blade... trust me.
The riving's knifes that sit below the blade's advantage are they allow a non-through cut leaving the knife on the saw.. if.. if... the cut is deeper than the height that the top of the knife extend up.
I prefer a splitter or riving knife that sits higher than the blade allowing me to attach a solid Euro style Crown guard. If the stock rides up in a kick-back.. it stops it. In essence the pawls do the same thing but after having my finger almost severed years ago with pawls (the saw was off at the time).. I will not use them.. period.
To solve that problem for me... I have a custom.. quick release splitter that comes off in about 2 seconds with a 1/3 turn of a lever. I eliminate pawls and drill holes on top of the splitter to attach a home-made crown guard. The Crown guard in my case is a piece of spalted pecan I had left over. I drill another hole on the Crown in the forward position and added a plastic shield with a dust port for dust collection.
Hope that helps...
Sarge..
The "Sarge-Guard" is pictured below....
Edited 6/27/2008 12:00 pm ET by SARGEgrinder47
Sarge,
What ever happened to your beloved BT3000? Both of mine are still in service but one's at my dad's house and the other is at a friend's house. Len
"You cannot antagonize and influence at the same time. " J. S. Knox
I used it until about 6 months ago with a dedicated dado mounted. I built a special safety fence and added over-head protection to the sliding miter. But.. I found a better way to cut a dado so it sat in the back shop collecting dust. Still fully operational but no real need at this point.
So... I sold it to a local WW downt the street as he needed another one for his summer cabin in the mountains as he's retired and his family spends the summers there. Still running strong and without a "burp" from what I hear. A much better saw than most would give credit for simply because it had the name Ryobi on the side. But.. you already know that as most don't. :>)
Regards...
A much better saw than most would give credit for simply because it had the name Ryobi on the side..
I have more than a few Ryobi tools.. Cheeeeep and work in most cases! I have several Ryobi routers that work GREAT except for the plunge! My old 3000 TS something with the 'slider' was wonderful for what I used it for.
I only have one Ryobi router that plunges nice.. I had to put Nylock? dog point set screws in the castings for it to plunge straight!
But it was fun doing it!
Edited 6/27/2008 1:43 pm by WillGeorge
Thanks Sarge -- you the man. The guard that comes with the SC is frankly flimsy compared with the PM, and I don't trust pawls either. I've taken to using a pair of Grrrippers for all but large workpieces. I'll see if I can adapt your uncommon sense solution to the SC splitter. One thing that puzzles me is having a "European" knife fitted to the width of the sawblade, but one-size-fits-all for the US type. If width matters for one, why not for the other?
The design of these saws seems to make it easy to add aftermarket pawl-free European knives if the manufacturer doesn't provide them -- they sit in a slot behind the sawblade. But retrofitting the entire system is something else. A friend of mine who owns an older General was told a retrofit was available -- for around $700. Safety has no price, but how much safety are you getting if you have to modify the system to make it work?
Jim
Thanks for the info., all good. Has anyone seen the Fine Woodworking DVD "Mastering the Table Saw"? In the video Kelly uses a contractor's saw with an after market splitter.
Does anyone know who makes it or sells one.
Thanks
i like your guard/dust collector that hooks on to your splitter. Is the clear dust hood custom or of the shelf?thanks
The dust shield is "off the shelf" then "customized" Sharp. It is a Penn State shield as the one that comes with the over-head dust pick-up and guard they sell. But... they offer it separate for $25 or it was at the time I purchased it.
I just took their rectangular box shape and shaped it on my smaller BS to fit in conjunction with my home-made Crown guard. Added a little contour here and there to assist a smoother lift once the stock meets the front leading edge. I made my own over-head support swing from some old black pipe that were used as pipe clamps once upon a time in the olden days when dinosaurs ruled. heehee.....
I suppose you could say I am cheap... but Forest Girl has very nicely labeled me as frugal. I suppose you could sum it up by saying that I am a butcher of wood but... a master of modification especially of re-cycle.
Regards...
Sarge..
And can anyone who has used riving knives explain why the type with guard and pawls offers any improvement over the European type?
NO... BUT I have an opinion.. With a riving knife that goes over the blade by whatever the design is..... How can you cut a tenon or whatever less than the height of the riving knife?
Am I overlooking something? Or do you take it off like my older stuff with a splitter?
Jim and Will..
I will address both as I have to go make 50 pins to mate 50 tails I cut last night for DT's. I think there is much confusion about a simple riving knife. Not all have the same design (some are taller.. some extend over the back of the blade.. etc. etc.). A riving knife simply goes up and down with the blade and tilts with it. I also is spaced the same distance in all positions from knife to the back of the blade.
Ideally is is just a "hair" narrower than the blade instead of very thin as on most of our current saws. I would require a different thickness for both full kerf and thin kert blade to meet those requirements. But most manufacturers will by-pass that and probably build one that is a hair thinner than a TK blade so one knife serves both.
The big confussion I believe comes with not having to remove it for a non through cut. If a RK sits slightly below the top of blade and your say dado is very shallow.. you don't have to remove the knife. But if the cut is deeper you do. The advantage to not removing the knife is just that.. hyou save about 10 seconds and that's it period and here's why...
You are no better off having a riving knife still attached with a dado or other non-through cut than you would be without it being there. Common sense tells you that unless the cut is just slightly wider than the riving knife the knife or splitter is useless regardless if on or off the saw. How many non-through cuts are you going to make that are not over .124 of an inch or the approximate width of a saw-blade. Non in your life-time probably..
So bottom line is that with a non through cut you are no better off with a riving knife than a splitter. If your riving knife sits low enough to avoid the depth of your cut... you can leave it on. If your splitter were to sit below the depth of cut you could do the same. But it it doesn't and the more likely case... both have to come off. There is no magic in a riving knife that makes it wide enough to keep a 1/4".. 1/2" or 3/4" dado from defeating its purpose of keeping the cut from pinching the back of the blade. If you have a non throuth 3/4" dado that would release enough tension to compress that far back to the blade it would have probably exploded when you first ripped it. ha.. ha... ha..ha..ha..
Some of the things people are giving the riving knife credit for it nothing more than not thinking it through. A riving knife is safer over-all as it remains the same distance from the back teeth and rises and falls with the blade.. it also tilts with the blade. But... as far as a non-through cut goes having a riving knife is no safer than a splitter as it performs no function worthwhile in that role... an if is taller than the depth of the cut it Must come off the saw to negotiate the cut.
Hope that takes some away some of the mystery as there is no real mystery other than that created by those that are not aware of it's simple functions IMO>
Regards...
Sarge... who is off to do pins
Sorry for the spelling as this computer thingy wouldn't allow spell check for whatever reason and I have work to do and time's a-wastin. :>)
Edited 6/27/2008 1:56 pm ET by SARGEgrinder47
Thanks Sarge. I guess the low knife has a function if you do use the Grrripper or something like it for through cuts on small stock. The Grr.. passes over the blade with very little clearance, so a conventional splitter has to be removed. I've always felt comfortable enough using the Gr.. on its own, but I suppose a riving knife adds an element of safety.
Jim
I'm confused. If the riving knive is even a shade lower than the blade top then the saw or dado blade creates a space for it as it cuts, so it would never have to come off the saw because of non-through cuts. You might have to have a 10" dado set for the standard riving knive to stay below the top however.
I agree it has little function on a non-through cut, but little is needed since those cuts seldom create kickback. I suppose that if it is aligned to the right side of the blade it would still help to hold the board toward the fence.
I've only ever had an 8" dado set, so I'd have to take it off. There would be no guesswork involved because you'd see the knife sticking up like a shark's fin above the blade, preventing the workpiece from going through. The knife is held in place by a spring-loaded pin held in by a plastic screw knob, so you can remove it in seconds.
Incidentally the standard tall knife on my saw isn't TK, it's 3mm, which I suppose might cause a problem for a TK blade?
Jim
If the knife is taller than the depth of the cut Steve and the created opening will not clear it.. it has to come off the saw or the cut can be forwarded into the blade any further.
***
I agree it has little function on a non-through cut, but little is needed since those cuts seldom create kickback. I suppose that if it is aligned to the right side of the blade it would still help to hold the board toward the fence"... Steve
It has to be aligned center line of a standard blade so it really can't be positioned farther right or left without taking time to do shimming on the mount plate that would move it right. It could not be moved left as the base of the knife meets the surface of the mount plate.
Even if were moved right... even a 1/4" dado which is about as small as anyone would use in most cases... a kick-back from a 3-5 HP saw is violent enough as you know to move the stock.. hit the knife or splitter of not full height with violent force and the stock is likely to go up. People that have a riving knife with no Crown guard as I use are not as safe as I am with a splitter and Crown in a standard 90* cut IMO.
If stock shoots straight up from the force to the rear-rising teeth... a riving knife or splitter won't stop that travel without a crown above it designed to counter rising stock going skyward and God knows from there. The value of a riving knife is that it rides close to back of blade teeth on any through cut and tilts on a through cut when a angle cut on the TS is called for.
Those are the sole advantages as you can have a splitter custom made to just under blade width as I do. And not all riving knifes meet that qualification as hardly any stock splitter would. I purchased my splitter plate from Lee Styrone who makes the excellent Shark Guard. He sold me the high quality plate he custom makes and machines the base for my particular saw to recieve and quick release.
I added my own crown guard and dust sheild as comes with Lee's Shark Guard set-up. He includes 3 splitters of various widths for various heights that move the front edge closer to the teeth as a RV would. Excellent design.. machining and a great value. He has been doing it on the side for several years and does a day job. One of his is about a 2 month wait to customize to your saw... but well worth the wait for those that will not tackle any of their own machining..
Regards...
Sarge..
I want to take a moment to thank the over sea's crowd for sharing
their safer techniques.
As a carpenter during the day and a life long American builder it
is very ingrained to rip all that "JUNK" off my saw.
Well since I've been on this forum I've made it a point to listen
to how others use their saws. I'm proud to say my contractor's saw
is one of the few on the job with a riving knife and a feather board.
I get strange looks now and again (actually all the time)but my cuts
are cleaner, straighter and safer!
Can't say as I'm ready for the over the top guards, pawls and what not
but hey... Baby steps right?
"You might have to have a 10" dado set for the standard riving knive to stay below the top however."
Steve, here are images of the two riving knife patterns common on the saws we use in Europe. European saws sold in the US use one or the other of these types. The new American versions of riving knife may differ from these.
The style below sits both behind and above the blade. The crown guard mounts on the knife.
View Image
Below is the dagger type of riving knife. The crown guard is mounted on a separate arm as you can see. This is one of the saws I use. It's a sliding table saw with a 3050 mm stroke (10' roughly.) The riving knife sits behind the blade and is set anywhere from about 0.5 mm or so below the highest point of the blade to a setting some point just above the highest point of the blade. Change the blade diameter and you simply move the knife up and down in the holding bracket to suit-- there are slots in the knife for such adjustments.
I've used both riving knife patterns behind sawblades that varied in diameter mostly in the range of about 12" to 18". By that I mean a single riving knife will usually accomodate blades that vary in diameter by between 4" and 6". The greater the range of blade diameter the riving knife must accomodate, the greater is the compromise in the setting of the knife close to the teeth, particularly at the extremities of the blade diameter range the saw will take-- most saws I've worked with will take blades within the 4" diameter range, eg, 12"- 16" or 14" to 18", but some go from, say, 12" to 18" diameter blades. Some I've worked with took blades between about 20" and 26" diameter, or more, and those saws are wood, gristle, bone and flesh eating 15 or more HP monsters that you really don't want to mess about with, ha, ha.
View Image
A dado blade makes the functionality of any riving knife virtually nil as you say. A buried standard sawblade cut is made safer with a dagger type riving knife, but both a dado blade operation and a buried table saw blade cut are operations a European like me would never make, so there's nothing to talk about on the safety front anyway as far as I'm concerned. For that kind of cut I'd use a spindle moulder (shaper), 3 phase overhead router, table mounted inverted router, hand held router, radial arm saw; or even possibly a biscuit jointer or a hand held circular saw. Slainte.
Richard Jones Furniture
Edited 6/27/2008 9:45 pm by SgianDubh
Thanks Richard as there is much confusion as to what a riving knife really is I find. Some un-knowingly diss if off as useless and others have mystefied it to the point of being the "holy grail" and if their saw had one.. they are now safe without all the other things (short fence.. crown.. etc. etc.) that are required to do so.
And for those reading this.. Richard Jones is the person I first learned about riviing knives.. crown gaurds.. short fences.. etc. And since I did I am not without any of them with the exception my saw has a modified splitter with crown gaurd. But... I only rip on the TS with angles cuts going to the SCMS..
I do non-through cuts as box joints with a miter gauge where my hands don't come near the blade. And I do regular dadoes on the TS with a little special help over-head I pulled from a scrap bin. I don't put my hands within 8" of a spinning blade period.. even with dadoes..
A pic of a dado operation at my shop... The push stick on the fence is laid flat to get the tail of the stock through the blade.
Regards and hope the book is coming well...
Sarge..
Well, you're largely right Sarge. A riving knife on its own isn't a kind of saw safety panacea. It's really only an additional safety item if you use a saw like Europeans use one. We don't do dado cuts and non-through cuts on a saw. The only thing a saw does as far as we are concerned is rip and cross cut wood to a set dimension, with either a so called 'short' fence or by using a sliding table.
We don't do dado cuts, finger joints, tenons, mouldings, etc, and all the other stuff north Americans do on a saw. There are much better machines for for doing those jobs, and we tend to use them instead.
Try to use a saw with a riving knife just like north Americans generally use a Delta cabinet saw and you're pretty much back to all the dangers inherent in that kind of saw usage. Slainte.Richard Jones Furniture
The European standard is just that European and only of passing relevance to the US market. I strongly suspect that in most cases the knives will follow the Powermatic model where there are two variants of the riving knive, including one that does fit below the 10" blade.
By the way, it is not legislation that will bring about the change. It is essentially a consensus of the manufacturers that agreed to the UL listing requirement change that will cause the shift. UL is a private organization, not a government agency.
Sarge. a saw with a riving knive can make all cuts, even a 2" non-through cut, as long as the top of the knive is a bit below the top of the blade. Remember the wood has been cut away before it reaches the riving knife.
The principle advantage of the riving knife for the American market is precisely that it does not have to be removed for non-through cuts or for cross cuts on a sled and the like. Thus, it has much better odds of remaining on the saw. It is likely to be marginally better at preventing kickback because it is closer to the blade, at all blade heights. But keeping it in place is the big deal here where so many splitters are never used again after having been removed a time or two. Compared to no splitter the riving knive is a big safety improvement--not a panacea but still important. And, largely for the convenience factor a great many of them are removed or never installed again.
I'd bet a fair chunk that American's are not going to give up using dados, and making other non-through cuts on their table saws, at least anytime soon. It's too ingrained in our methods of work.
"Sarge. a saw with a riving knife can make all cuts, even a 2" non-through cut, as long as the top of the knife is a bit below the top of the blade. Remember the wood has been cut away before it reaches the riving knife"... Steve
***
You are correct as I made this mistake once before not totally thinking it through. But.. what I stated about the width takes away the the single role it plays in safety when there is no crown on top. I change blades about 4 times a day on average.. yesterday 5. Three times to switch from the Freud box cutter dado back to rip which is my main function. I have to remove my modified splitter but it takes lifting the insert which has to be lifted anyway and turning one lever 1/3 of a turn. Then pull a stainless steel lock pin that has a wire ring attached as a hand grenade does.
Four second operation. So... do I re-install the splitter-crown-plastic shield when I put my dedicated rip blade back on? Every time without fail. And I really don't have any hesitation about using the Freud box cutter dado to do dadoes on the TS. The picture I posted showed a long grain dado. I do cross cut dadoes using a miter gauge. But.. the way I use it keeps my hands no closer than 8" of the saw.
Riving knives are great for their purpose.. but that purpose is limited and further aid is needed IMO. Am a I afraid to turn a saw on without a riving knife or the saw being a Sawstop. Absolutely not as I use one daily. But... I do implement every safety feature I can and do not put my hands closer than 8" to the blade when spinning.
In other words.. I totally concentrate on what I am doing.. keep the lane clear.. use safety devices and practice common sense at all times when cutter heads are running. But.. as you stated.... many don't as they find it too much trouble. I don't see it as trouble.. I see it as standard operating procedure in my shop and it will be done...
Regards...
Sarge..
I think Steve hit it on the head in his previous post. While your methods certainly are beyond question safer (I''d
go so far as to say saner) it seams truly unworkable from our
perspective. I know that isn't the case, but it is a real
mental effort to not just reject it.
As I said putting a riving knife on my saw turns heads. But it's
non interfering nature quickly wins acceptance, and I think there
is a certain satisfaction from the cleaner feed.
Is it safer?
Yes
Is it safe enough?
Probably not I do think our prejudice will change, but it's going to take time. My question FINALLY! I haven't found the wood riding up over the blade to be much of a problem.
Is this more common when using the larger push sticks, pads etc? I was thinking maybe, it is exacerbated by not coming within
8" of the blade.
I had and used a TS with a riving knife for several years before most here even knew what a riving knife was. Do I think it is safer than a splitter because it has the capability to rise and fall - tilt with the blade while maintaining the same distance from the rear of the blade teeth... Yes.
The TS I currently have does not have a riving knife.. will I hesitate to stop using it to purchase a slider or one that does... No. I take about every precaution that can be taken with the U.S. saw that can be taken to the extent of modification to add a splitter just a hair under a full kerf blade width. I modified that precise splitter to be taken off or re-installed in under 10 seconds total.
I use a spring-board left of blade.. short fence (another safety issue not being discussed here).. a Crown guard above.. and shop made (ten minutes invested) over-head hold downs (similar to feather-boards) on the fence to help tie stock down tight to the table. I keep the lane clear at all times when a blade is spinning.
I work in the shop an average of 6-10 hours a day changing blades an average of four times. A blade change takes about 2 minutes.. removing or re-installing the modified splitter I use takes under 10 seconds and adding a hold down another 10 seconds. My spring-board stays on the table left as I made it in a way to slide almost off the left side of the saw.
I strickily rip on a table-saw.. with all cross-cuts going to a SCMS modified to cross-cut 16' with support on both sides. I cut tenons by hand saw normally but will use the BS to cut down to shoulder and take the shoulder as pictured using an artificial fence on the TS when I have more than 6 or so to cut. I will use a Freud box cutter dado to do box joints with a special miter gauge.. and I do cross cut-cut and long grain dadoes with the same set.
I sold a stacked dado set with stacked blades which have very few teeth. With their gang-cutters I consider a stacked set un-safe. The box set from Freud has flat teeth.. many of them and they are extremely sharp compared to a stack set. But.. it allow on 1/4" and 3/8" dadoes. But.... with a double pass I achiever 1/2" and 3/4" perfectly as mic'ed out the Freud is a true 1/4" and 3/8". No shims and no gang cutters.
Now.... ********
"I haven't found the wood riding up over the blade to be much of a problem.Is this more common when using the larger push sticks, pads etc?
I was thinking maybe, it is exacerbated by not coming within 8" of the blade"... Henley
*******
I don't have a "problem" with stock riding up either and I rip up to 14' daily with friction support surfaces front and rear (another safety issue not being discussed here) alone. But... I raise the blade higher than most to give the forward teeth a more downward angle which helps tie stock down. Most cases I have seen an upward launch.. it from the blade being set low as recommended by some manufactures.
Or..... if stock gets twisted and catches the "rear rising" (the real danger of a blade spinning) teeth it will go side-ways and then up. Can that happen (especially for those that do thin plywood on their saw which I don't period).... Most definitely! But... if it were to occur I have it contained with the use of a Crown guard over-head. A riving knife or spliter will not stop a launch!
So.... do I think that not putting my hands closer than 8" to the blade can contribute to stock rising... Not really. There are several types of push sticks and hand pads that can be made in under 20 minutes as you are not limited to one because you are too lazy to see a particular ones limitations.
What I think is that riving knifes are safer than a standard splitter "if you have one on the saw" but it doesn't come close to a final solution. I also think that most are too lazy to utilize quick, cheap methods to make a TS without a riving knife or slider much safer than it came from the factory.
I also think that a riving knife can be "dangerous".. but "not from it's design" but the fact that many may mis-understand that it is a "single issue" of safety and only covers a limited area. That can "lull" someone to practice un-safe procedure because they think they are safe with "just" a riving knife. So... bottom line IMO is "what it really contributes must be understood and understood fully".
Regards...
Sarge..
Sarge,
First off thank you for taking the time to answer so thoroughly and
frankly.
The issue of the half fence is high on my list of "to learn more about"
but that's for another day or thread as the case may be.
All,
Question: Do any of you folks see any problems using a riving knife when using either a crosscut sled or when making cove cuts on the tablesaw?
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Bob,
A riving knife wouldn't get in the way using a sled.
However, I would think (though I haven't tried it), that the wood would contact the riving knife when cove cutting on a tablesaw. And, since it would be worthless when doing that particular cut anyway, you'd want to remove it..
ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon
I don´t believe the use of the riving knives only, without the pawls are more secure than the guard-splitter with pawls. I haven´t been using the table saw of 3 H.P.,only one of 1-3/4 H.P. Are the pawls useless here, for detain the wood in case of kickback?. I prefer a splitter with pawls or a riving knives with pawls, I use it all the times except when I make non through cuts.--------------------------------------------------Yo no creo que el uso de el separador solo, sin los retenedores sea mas seguro que la guarda con el separador y los retenedores. Yo no he estado usando la sierra de 3 H.P., solo la sierra de 1-3/4 H.P. . ¿Son los retenedores inutiles aqui, para detener la madera en caso de un retroceso? Yo prefiero el separador con los retenedores, los uso todo el tiempo excepto cuado hago cortes no completos.-
The pawls have a purpose, Manysal. That purpose is to counter stock that would ride up. I don't use pawls... but I do use an over-head guard called a crown guard to stop an up-lift of the stock. I used to use the pawls until one day there was an incident that changed that.
I had the saw un-plugged changing blades. The plastic shield was in the up position to keep it out of the way of the wrenches to loosen the arbor nut. Obviously I jarred the table somehow and the shield and pawls came down suddenly. The pawl went deep in my finger almost severing it off and a trip to the hospital emergency room.
From that point forward.. I took off the pawls and had no over-head guard of any type. Then I was en-lightened my Richard Jones that post here about Crown guards. I built one as you see in the picture in post 20 and have used it ever since unless doing a non-through cut.
Regards...
Sarge..
I'm none too keen on pawls myself, but I don't think that kind of accident is likely any more on the riving knife models, since you pretty much have to remove the guard to change blades, and it only takes a minute. The pawls still get in the way of your fingers since they're in contact with the insert -- which now has a plastic covering at the rear to stop damage to the insert. However that's more of a nuisance than a hazard, I think. I might change my tune the next time I draw blood. Making a crown guard changes slightly also. You can't just attach the plastic guard to the crown directly, the guard has to be on the end of a longish swivel because the knife goes down into the table, unlike a splitter. It's not fair -- forces you to think!
Cheers, Jim
Interesting Jim. I gave some thought to your comment about not being able to attach a crown guard to a riving knife directly. I had a TS with a RK a while back. All riving knives are not the same as some actually are taller than the blade as this one was. I attached the crown guard to the knife by drilling two holes on top that aligns with two holes drilled through the side of the crown. I used 2 T bolts with threaded knobs that allowed it to be installed and removed very quickly.
But.. when the blade was lowered to a certain point... the crown did have to be removed for the stock to clear. So.. not perfect but it worked fine considering I mainly rip on a TS and usually 4/4.. 5/4.. 6/4.. up to 10/4. Anything below 4/4 did require the crown to come off. But even then I just clamp a piece of scrap to the fence with two clamps to allow the stock to ride under it. A field improvised partial crown depending on how you look at it.
I have noticed that the newer PM TS have a low rider riving knife that sits slightly below the blade. So... the above would be useless as you mentioned on that saw if that is the case. When I attend IWF next month... I am going to take notice of which saws RK's sit low and who's sits high just out of curiosity.
Regards...
Sarge..
Hi Sarge. Should have made myself clearer, as usual.
I've got a SC, and they give you both a high knife with pawls and a guard, and a pair of low knives without. There's no problem about attaching a crown to the high knife, which looks much like your set up -- there's always enough clearance above the blade, even when the blade is dropped down. The difference is that you can't attach the plastic guard directly to the crown, except when the blade is at its highest point. You need a pair of swivel arms between the crown and the guard so that the guard stays above the table while the blade lowers. That's what's on the SC guard, and it shouldn't be too difficult to rob the swivel arms from it and transfer them to a PS guard and a crown.
I don't know that I'd bother doing that, given that the pawls are less dangerous than they used to be, if it wasn't for dust collection. The SC guard doesn't have any, and it's so narrow that you couldn't cut out a decent sized circle on top to add your own. About the only thing you could do is cut a port in the side, which would be awkward. So I'll probably do something with the PS guard.
It's not all extra work with a riving knife. Because the aperture in the table insert has to be open all the way to the back you can easily make zero-clearance inserts with the factory insert still in place and using the regular blade -- no need to faff around with an 8" one.
Cheers, Jim
I don´t believe the use of the riving knives only, without the pawls are more secure than the guard-splitter with pawls.
I think you have a point there!
Been hit with Kickbach only twice in about 40 or longer years... The last time at age 65...When it happened... I thought I would see if God really exists in a few moments! I pulled through it so I guess THERE IS a GOD! All I ever heard from God was a little laugh... And the words.. I taught you better en' that!
Well said Steve. Good, clear post and explanation.
I wish there was a way to retrofit my Grizzly 1023 with a riving knife. As it is, I need to take off the splitter and then put it back on every time I do a non-through cut. It's time consuming, and has the tendency to make one want to just remove the splitter and never put it back on again.
A riving knife would be able to stay in place for many more of the cuts I do, and, as you said, would therefore be much more likely to be left in place..
ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon
Steve and Richard,Posts 42346.18 and 42346.19 succinctly sum up the entire subject of European and North American table saw practices.I learned "American" techniques most of my life until I became aware of European equipment and practices about 15 years ago. I don't want to start a battle here, but I am simply amazed by the lack of awareness or adoption of equipment and techniques by American workers that have been common place in Europe, Great Britain, Australia, New Zealand for many years. To my way of thinking those standards are so far superior to American methods as to make our commonly accepted ways utterly stupid.In Europe, the dado cut has been considered a dangerous practice and is actually illegal in a commercial shop.But there has been a trend on European equipment to give a nod to the necessity of the dado type of cut. There is not even room on the arbor of many Euro saws for a dado set. But my Hammer sliding table saw accepts a dado head that is essentially a shaper cutter that operates in a vertical position. I haven't bought the Hammer "dado" head yet, and prefer to achieve such cuts by other means, but the saw is ready for it if I want to spend about $700.Rich
Rich, Steve made a fair point in response to my post. His interest in how Europeans use table saws is only peripheral. From the way I read his post he's pretty much only interested in what application a European type safety device might have for American style woodworking.
That's fair enough. I don't need to make changes in my working methods to incorporate this new fangled riving knife thing (sic) that has started making waves in north America over the last two or three years. Riving knives are old hat; they've been around all my working life and for decades before that. I already know how to use them and their accompanying crown guards in our radically different sawing techniques.
I'm no more likely to adopt north American style woodworking practices than Steve's post suggests he is likely to adopt European woodworking practices. So as far as I can see he's perfectly entitled to take the line he did.
It's a somewhat different approach to yours where you have looked at the woodworking philosophies and practices in both north America and Europe and you've reached conclusions. I've done the same, and was rather forced to do so when I lived and worked in the US. It's my opinion that not all European practices are better. Some are, but conversely there are many American woodworking techniques and philosophies that are far ahead of us Europeans; I've adopted a few of them anyway. Slainte.Richard Jones Furniture
I'm not really wanting to make an argument about whether European practices or American practices are superior. I'm merely making an observation about what I would expect the broader market in the US would accept. So all I'm really saying is that anything that gets anti-kick back devise that is actually used will be a real advantage. For info, I am quite religious about reinstalling by Biesemeyer spltter on my old Unisaw, but never use the Brett guard that I have. I'd have a slider in a heart beat if I had room and budget for it.
I will say I don't quite understand how dado cuts on a table saw are unsafe--except possibly on saws which have such rapid motor brakes that the momentum of the heavy dado set could cause it to "unwind". Is that the rationale?
Edited 6/28/2008 5:49 pm ET by SteveSchoene
Steve, There is definitely that rapid braking factor nowadays to take into account. That's a regulation that's been in place for approximately ten or twelve years.
I suppose the risks of using a dado blade are much the same as any buried sawblade cut, eg, stress release leading to wood pinching after the cut, or the board twisting away from the fence, whether cross cut or rip. Either scenario can lead to kickback. There's also the greater width of a dado cut compared to the width of a single sawblade cut; there's probably a somewhat greater tendency for the board to rise off the saw table with a wide slot being excavated. Lastly, thinking of things off the top of my head, there's the possibility of passing the heel of the hand over a buried blade, whether dado type or normal width.
These are all risk factors, but there are steps that can be taken to reduce the chance of things going wrong, eg, hold downs, finger boards, clamps, push sticks and so on.
I don't know all the reasons for our non-use of dado blades in table saws, but dado blades in table saws used to have quite a reputation for accidents and operator injury. The Health and Safety Executive (HSE) has guidelines for their use. We can buy and use dado blades, and the HSE (I think without checking their website again right now) describes making tunnels, hold-downs, the use of Shaw guards, push sticks, etc.
All this presumes table saw arbors are long enough to take a dado blade, and the fact is that it's near enough impossible to find a saw sold to the British market with such an arbor. I'm not sure why manufacturers took this route of making it impossible to fit a dado blade to their machines.
Perhaps they decided that too many people were getting injured using dado blades on their machines due to improper or inadequate user devised additional safety precautions. Perhaps they feared there would be an outcry for the manufacturers to provide the safety gear. Perhaps they feared being sued by too many injured operators or their families. Whatever the reason, they make saws with arbors too short so we can't fit dado blades. There's one exception I can think of where the saw manufacturer also supplies a sort of mini fixed width dado like blade that fits their machine: I don't know much about that specific machine, nor recall the name of the manufacturer at the moment, and can't remember much about their trenching blade as I think they call them.
So, we can buy dado blades. They're pretty rare, and the few I've seen are almost exclusively fitted to radial arm saws and used for cutting things like tenons and trenches across the width of stock. That's about all I can tell you in a short post without additional research which, right now, I don't have time for. Slainte.
Richard Jones Furniture
Edited 6/29/2008 5:52 am by SgianDubh
Thanks much.
I agree with Richard about what can happen with a dado cutter. To the point I sold my stacked set and vowed not to use a dado again... until I saw a Freud box cutter set in use and was allowed to use it. Two blades only and by the way you faced them you get either 1/4" or 3/8" exact. Each blade has 20 very sharp teeth and placed side by side you have an approximate 1/2" gap between teeth with deep gullets. So interlocked you have 40 teeth.
The importance here to me was the number of teeth more more significantly there are no "gang cutters" between them. Those have very few teeth I compare to throwing a dull or blunt axe head at a tree in an attempt to sever it. Lots of high impact but little severing IMO. Basically not severing the wood out but "knocking" it out.
And what Richard said about additional safety aids should not be over-looked IMO. I have already stated the one's I used but very few probably read a post carefully when a poster is an amateur as I see it. To avoid twist on a long grain cut I block left with a spring-board.. block right with the fence.. block up with a home-made bridge guard with an additional feather attached to the fence before the cut. The only place left for stock to travel is front rear... so simply you never violate "keeping the lane clear"!
Cross-cut is done with miter gauge and sacrificial fence attached before the blade. Both cuts can be no wider than 3/8" due to only two blades. So.. if one desires a dado or channel 1/2" or 3/4" you have to make a double pass with 40 teeth and no gang cutters. I do tenon vertical sides on a BS and cross-cut the shoulders with the box cutters using the sacrificial fence.
I rarely have to cut deeper than 3/8" on one pass... but if a 1/2" or 3/4" depth is required then I make two passes or three by raising the blade in increments of no more than 3/8" on each pass. It takes a few minutes more but I don't have dead-lines and take a few minutes more.
I experienced the basic same issues of rise.. twist.. etc. with a stacked dado set as I already mentioned in an earlier post so... I got rid of the stacked set as it was very difficult to set to exact widths and I considered the gang cutters very in-efficient and dangerous.
But since acquisition of the box cutter set... I will do any dado.. tenon shoulder.. lap joint with it.... with the aid of additional safety devices that I can make in very little time usually from a scrap bin.
That's my personal story... I backed it up with "why" I won't use a stacked dado set with gang cutters but will the box set and.... I'm sticking with it. :>)
Regards...
Sarge..
Edited 6/29/2008 9:55 am ET by SARGEgrinder47
"I don't know all the reasons for our non-use of dado blades in table saws, but dado blades in table saws used to have quite a reputation for accidents and operator injury."
I think I've got to agree with you there, Richard, but what struck me from the accident reports I've read is the extent of the damage caused by dado heads as opposed to standard sawblades. Overall accidents aren't all that common, but when they do occur the effects are much worse. It's possible to reattach a finger severed by a clean cut from a standard table saw blade, but what do you do with the pound of hamburger meat resulting from a stacked dado saw pull-in?
"I'm not sure why manufacturers took this route of making it impossible to fit a dado blade to their machines."
In the case of the UK it was the BSI (British Standards Institute, our equivalent in a way to Underwriters Laboratories) standard which limits the width of tooling accommodated on a BSI-standard saw to 16mm (5/8in). I believe that the Germans, Dutch and others enacted similar regulations at the same tame in the mid to late 1990s. And all saws sold in the EU are supposed to meet BSI (or equivalent) standards to be CE marked
"Whatever the reason, they make saws with arbors too short so we can't fit dado blades. There's one exception I can think of where the saw manufacturer also supplies a sort of mini fixed width dado like blade that fits their machine: I don't know much about that specific machine, nor recall the name of the manufacturer at the moment, and can't remember much about their trenching blade as I think they call them."
That is the German company Scheppach, although French firm Kity also sold the same system for their machines and deWalt offer a very similar cutter set for use on their radial arm saws her in the EU. Incidentally these sets are all designed to withstand standard 10 second braking without incident. Hamer/Felder also offer a similar system for their machines
As to why I personally dislike stacked saw dado sets, that's down to having had to machine through housings (through dados) with them in far too many times for my liking in poor quality knotty pine in years gone by. Often when you hit a big knot the work would try to climb the blade which didn't really feel all that comfortable. On the odd occasion we'd also have pieces disintegrate when a thunder shake was "found" by the dado head (because we also made stuff from windfall trees, hedgerow thinnings, etc). That means these days if I do that sort of cut I use a radial arm saw and a 2-part shaper style head which seems to cut much more smoothly
Scrit
If you would be so kind Scrit.. I read your post to Richard carefully and would like your opinion (and Richards) after reading post #34 on what I use to cut dadoes. It's not a stacked set with what I consider worthless gang cutters sandwiched between to what I consider inferior blades. It consist of two blades back to back.
Now... my Box Cutter set falls under BSI requirement of 16 mm and is only 9 mm at the widest setting back to back.. 6 mm with writing out. Each blade has 20 very sharp teeth ground flat. I use a European 20 T rip saw blade with a 3 mm kerf with a flat grind. I can rip through hard-wood 3" + thick with it with a 3 mm kerf with no problems. I cut only to a depth of 9 mm and raise the blade in increments if more is needed which is seldom.
Obviously I am well within BSI standards cutting dadoes.. cross-cutting shoulders on tenons as I do the vertical cut on a BS. And I do not use stock with knots as any are carefully culled out when I prep a piece of stock from the mill preparing for usage.
Do you consider me within BSI safety standards is the question I pose to you?
And.. I am aware that Euro machines have short arbors.. but these two blades I use to cut dadoes have a plate thickness of 4 mm back to back as I just measured them. Is your arbors (and I know it might vary from one machine company to another) long enough to take on 4mm or 5 mm maximum as I only measured with a rule and they were not mic'ed? That's question 2.
Thanks if you can reply.. If you see this Richard, I would also like your take on the set up I use to do dadoes on the TS keeping in mind that my father's Chevrolet (stacked dado set) may not be my Chevrolet!
Regards...
Sarge..
Sarge, you seem to try and make using a dado type blade as safe as you reasonably can by using plenty of adequate hold downs and the like. I don't think you can do much more.
I don't feel able to comment on the BSI comparisons or standards you mentioned. Slainte.Richard Jones Furniture
Thank for your opinion Richard as I call it a dado.. but in essence it is just two 8" blades side by side with the teeth forming either a 1/4" or 3/8" kerf combined. The word stacked dado refers to gang cutters sandwiched between two very in-efficient excuses for blades IMO. They are bad enough but the gang cutters are essentially knocking the wood out by impact IMO.
Couple that with someone going 3/4" wide and 1/2" to 5/8" deep in one pass and you have the mix for trouble brewing. Don't ask how I know.. just rest assured that after the first time I sold my stacked set and there will be no more.
Again... thanks for your time and hope the book is going well...
Sarge..
and was rather forced to do so when I lived and worked in the US..
and was rather forced .. Us Americans NEVER do that! .. well most of us folks!
Our so called Goverment by Bush ...may have different ideas!.. As I am hauled of to someplace hidded that NOBHODY can find me when I post this...
Richard and Sarge,
I use a blade-following riving knife that sits just below blade heigh on my 10" TS. The knife is arout 4 inches deep behind the blade, 0.2mm less thick than the standard blade kerf and is 1-2mm from the teeth at al points. The knife has an L-shaped slot to attach the guard, using a Bristol lever (a kind of quick release lever). The knife is very stiff and does not deflect.
This configuration allows me to make non-through cuts by leaving off the guard. I make such cuts both against the fence (ripping) and using the cross-cut carriage. The knife enters the cut and prevents the work piece wandering into the ascending teeth at the back of the blade - i.e. prevents kick back - in just the same way as with a through cut.
I also use sprung hold downs (mounted on the fence-top T-track) and a feather board (mounted on the table-top T-track) when making rip non-through cuts. This is a belt to the riving knife braces for preventing kick-back. I push the work through this lot with a push stick. Typically I rip out a rabbet from a framing length with two cuts at right angles to each other, using this arrangement. When the cut is being made, the workpiece itself acts like the guard (i.e.covers the blade).
I cross-cut non-through cuts using the sliding table/fence. By moving the stop on the fence, the workpiece can be shifted along by a blade kerf-width so that multiple cuts form a dado. It takes a little while but probably less time than it would to mount a dado blade set. (Dados won't go on my saw anyway as the EU deems them dangerous thangs). Multiple non-through cuts allow me to easily make a dado across a plank to any width and depth, to an accuracy of 0.1mm. A shoulder plane cleans off any slight fuzz from the multiple-cut effect. The blade is not guarded except when the work piece passes over it, but my hands are well away from the blade, pushing the cross-cut fence.
When cross cutting ike this the riving knife is always up against one wall of the dado. There is also a hold down mounted on the T-track of cross-cut fence which keeps the work in place as the table is slid forward and back.
The guard goes back on to the riving knife in 1 second flat, for through cuts.
The only disadvanatge is that the guard will not go on the riving knife when it (and hence the blade) are set low in the table. The bottom edges of the guard, when it is in place, prevent the blade/knife from beng lowered to less than around 1" high. In practice, I only use the blade at a low height when making non-through cuts without the guard, as described above, so this is not really an issue.
Lataxe
Interesting Lataxe.. My Uni-saw is not designed for quick release so... I simply re-designed it. One quick 1/4 turn of a lever then pull the "grenade pin" or what others might call a safety pin I devised. I placed it on-board in case of violent launch there would be no chance of the impact knocking the crown and attached splitter off. My modified splitter simply has a U (facing the the opening down) that slips over an anchor bolt on my modified version.
Now.. if I felt it relevant.. I could make another splitter to use below the blade height as taking of and putting one on only takes a few seconds since I did some tinkering. And BTW... I also make the splitter with about .015 clearance right or blade side and around .025 clearance to the left of blade. The original splitter on a Uni-saw is about .072 total width using a .126 full kerf or .132 using my Euro 20 T ripper. Too narrow to be anything but marginally safe IMO.
Regards...
Sarge..
Edited 6/30/2008 8:29 pm ET by SARGEgrinder47
Edited 6/30/2008 8:29 pm ET by SARGEgrinder47
BTW Lataxe... how wide of a plate can you get on your arbor? Is there any room left at all on your saw as the box set I use combined has a plate diameter of only 4 mm. It you have any extra.. it might just fit on-board as that's not very wide like a standard dado set.
Back to glue-up of drawer 2.. the fun is over here for the moment. :>)
Regards...
Sarge..
Sarge,
The arbor of my TS leaves no room other than for the blade, the two pinned plates that sandwich it and the retaining nut (left hand thread). I believe this is EU safety policy implemented in the "short" arbor, to prevent we experimentalists from installing a dado set. :-)
The TS manufacturers Scheppach do sell a "groover", which is something like the slot-cutter one might put on a shaper; and replaces the saw blade. This has a small diameter and relatively few teeth that can be configured to make a maximum groove (dado) with of 15mm(5/8"). The riving knife canot be used with this thang.
Scheppach insist on you having an overhead SUVA guard and their work hold-downs if you want to use this groover. Given that all those parts come to many hundreds of pounds, as well as the limited capability of the arrangement, I just use an 80 tooth flat-top gound blade of standard 1/8" kerf to make dados.
Lots of cuts are required but it's still a fast and accurate method for making dados with a sliding table & crosscut fence sporting a microadjuster stop. Also, the riving knife then continues to work to some degree, as the newly cut wall of the dado moves against theknife as the cut is completed.
Lataxe
I have done what you currently do in the past, Lataxe. Yep.. that single blade will get it done though and for us old folks attempting to stay out of trouble not really all that bad as it keeps us occupied.
I did a 100' counter in semi-round for the company that I worked for. It was a custom show-room counter and I have never worked in the round before. Got some excellent advice from Dan at Odyssey Design. Anyway.. I had some thicker molding that had to be bent.. I don't know for sure how many relief cuts (single grooves) I had to cut, but it had to have been over 1000 on that project.
But.. a man has to do what a man has to do. :>)
Regards...
Sarge..
Late up as usual but I am a slow reader.
Yes, I make riving knives to fit the blade out of hard grade ally. The advantage to me of leaving the knife on in none through cuts is helping to keep the grooves straight, since I try not to use the fence in this situation. Usually trying to flatten a cupped board by opening grooves on the underside and inserting strips to restore some measure of stability without mucking up the face grain.
Interesting you mentioned grooving cupped boards and refilling the gap to relieve stress. I sometimes will make several relief cuts spaced narrowly and running length-wise with a single 1/8" kerf saw blade to relieve stress.
Just an idea I had once I was taught that relief cuts can aid in bending when working with a project that calls for curves without steam bending. I figured if it will do that.. why not use it to reverse the concept and straighten them out. I only do it to say a table-top that has bowed badly after glue up. I make the cuts and then clamp it down flat to acclimate. The the ends that would be seen get a 1/8" spline glued in to hide the evidence of the relief cut. It works for me also. ha.. ha...
Regards...
Sarge..
So bottom line is that with a non through cut you are no better off with a riving knife than a splitter. I wonder.. NOT saying you are wrong. Riving knife is not hanging off some rod a mile away and just by tolerances I'd bet more accurate? I wonder..
Powermatic saw (I saw) riving knife was WAY above the blade! I would like to cut some sticks one of these days in sort of safety with the riving knife just a tad below the blade height!!
Sorry to take so long to answer, Will. Our processor said "good-bye" Sunday night so I had to run and get one. My lovely just installed and transferred info so...
According to Lataxe the riving knife staying on just below the blade could be of some benefit. If you read some of those post carefully the jest is that even with a 3/4" wide cut.. the riving knife or splitter just below the blade could slow down (probably wouldn't check or stop it as I feel it would be a momentary diversion and ride up the short knife or splitter) somewhat. So... I suppose it might do that as I don't think I will test to find out.
But.. either way I feel without having some type of over-head check... having it on or off is no major difference other than the few seconds it takes me to take it off and put it on. But.. keep in mind that my saw is modified quite a bit and quick release .. quick attach is one of those modifications. Most don't have that on a standard U.S. saw with a splitter I can tell you that without it.. changing on a Uni-saw.. PM 66 (not PM 2000).. Griz 1023 is a PITA as I have done just that on those saws in the past.
So... bottom line is maybe... maybe not..
Regards...
Sarge..
I'm new to them but I guess that's why some manufacturers offer both types of knife -- the low one for non-through cuts and the guard type for ripcuts. Why PM doesn't offer bothe I don't know.
Jim
I think Sarge is in a league of his own when it comes to safety. I dont know about you, but when I had a cabinet saw the splitter sat on the shelf far more time than I care to admit. Since purchasing a Hammer with a riving knife and I can say that it is incredibly rare that I use my saw without it in place. It is simply to handy and effective not to put back after taking it off on when needed. Better? I think the logistics have been discussed so you decide. All of them are worthless if they sit on the shelf most of the time.
Brad
I never had any doubt I'd use the short rk -- I just wondered about the tall one with the guard and pawls. I'm going to modify it if I can along the lines that Sarge showed, with dust collection.
Regards, Jim
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