WEll; This is what happens when you use not the best of materials for a table saw insert.Had a little kick back tonight that sent piece of the table saw insert ( pictured),push stick and 4″x 4″ block flying across basement.I suspose baltic birch plywood would have been a better choice rather than red oak ., now it will be a plastic ,uhmw, phenolic or what ever, and i will have to figure a way to keep the back end of the insert secured . maybe drill and tap the ears that hold up the insert . Any body got any other ideas? Chris
Replies
It's a little hard to tel from the photo, but it looks like the insert you made was fairly thin- 1/4" maybe? Make it from 1/2" material. Plywood or mdf would do the job, although I don't think the oak you used was at fault. Make the insert a little thinner than the distance from the ears to the top of the saw. Insert small flathead screws into the underneath side where it sits on the ears. That way you can adjust the height to get it perfectly level with the saw top.
Drill a pilot hole in the back curve a little lower than the thickness of the saw table at that point. Tap in a small brad and let it stick out 1/2" or so. Use a little epoxy in the hole if you're concerned about the nail coming loose. The nail will prevent the insert from flipping up and out if the blade catches it.
Since a full size blade won't drop down enough to put the uncut insert all the way into the opening, use a dado set blade. Set the insert in place and clamp the saw fence down close to where the blade will come up. In addition, you can also hold the insert in place with a stick.(not directly over the blade, of course) Turn on the saw and slowly raise the blade until it cuts through the top of the insert. The nail will keep it from lifting out.
There are other methods of getting the slot cut in the insert, but this one seems to work pretty well. The only disadvantage is that dado blades cut a little wider kerf than a regular blade (at least mine does) so it won't give you a truly zero clearance insert, but it'll be pretty close.
You can buy inserts that are made pretty much the same way, but where's the fun in that? This one's almost free.
Alan
http://www.alancarterstudio.com
Woodood, It is about .460 thick.,this is the distance from the top of the table to the ears . This depth was the same on all five ears , so i just milled it to that dim.
I like your idea about putting a brad into the curve to help hold the front down. I'am going to explore that great idea more.
I was looking at it this am after a night of sleeping on the problem and i think i was pushing too hard down with the push stick. Since there is no ear to support the out feed end of the insert .I checked it and the insert will tilt down once down pressure from the push stick is past last ear. This is true with my factory insert and my oak ones .
I usually move the fence over part of the insert and than raise the blade.
Thanks for your input Chris
run the dadoe head up, but do not go all the way through staop at the point that there is about 1/8" of material left uncut....change blades to the one you really want to use ...then run your blade through to get teh zero clearance...
alot of the commercailly produced zero clearance plates have the back relieved in this manner....
Good idea. How do you know when you're 1/8" from breaking though? I suppose you could stop just as the blade starts to break through as well., yes?
Alan
http://www.alancarterstudio.com
A couple of thoughts about cutting the insert slot.<!----><!----><!---->
1. I have not tried this, but thought I would submit it for comment. Can you tilt the blade to 45, hold the plate down (with sticks/fence), and crank the blade slowly back up to 90 before raising the blade? This would create a hollow scoop under the insert but I think it would work fine.<!----><!---->
2. I have not tried this either, but perhaps you can stick (with carpet tape) the new blank on top of the old insert and raise the blade until you just break through (holding the taped insert down firmly with sticks, out of the line of fire).<!----><!---->
3. Use a router and a 1/4 straight bit to plow a groove (less than the thickness of the insert) to align with the blade.
CM,
I have the same saw. I bought the betterly tru-cut insert(aluminum) with replaceable inserts. It fits fairly snug, and has little spring-loaded ball bearings on the sides that help keep it in place. I do, however, keep some veneer scraps handy, and everytime I replace the insert in the saw I insert a strip of the veneer (about 1/4" wide) in the opening before I snap in the insert. Then I snap the veneer strip off flush with the saw's top. It keeps the insert very tight, yet I can easily pull it out when needed.
If you are not in the market to spend the money on something like that, then yes, I would recommend going with the plywood inserts rather than solid wood. And if they fit a tad loose, just try the veneer tip.
Lee
Ditto your Betterly insert, I have one also and love it.Work Safe, Count to 10 when your done for the day !!
Bruce S.
Today i ve come to the conclusion ,i think, that the insert plate pushed down because there is no ear on the ou.t feed silde of the insert .the possibility of the insert picking up is REALalso . But i think i was putting a lot of pressure down on the part and the insert tipped down caught the part and then threw it all out..Iam working on a way to not only stop the liftilng but also the tipping down. Thanks for your input I might look into that type of insert also. Chris
Chris, there was so little wood left on the ends, and it is lined up right down the grain. You should have known that would be too weak. Anyone could pick that up and just snap it with their fingers. You are lucky that you were not pushing something real small through when it broke. A push stick may not protect your hands when the insert caves in, and the stick has an opening to get jerked down into the cabinet. I think UHMW would be a poor choice for an insert. While it is nice and slick, it would be a little too flexible for my liking.You ought to talk to highflyer about those phenolic ones that he has.
KeithNewton. You are right , I should have got ten a solid material like a plastic. I guess i wasn't thinking and not thinking can cause bad accidents. I had used oak for many yrs on my sears but it had a lot more support all around the insert opening.As this PM has only five ears for support .
So, my plan is to make one that can't raise and at the same time cannot be pushed downsince (see pic) I"ll make one with a lip on out feed end of insert that will slide under table lip(see pic)and a block of plastic on bottom of insert that will sit on boss that is painted white in pic. This will prevent it from being pushed down. Chris
cmiller,
If you can stand one more idea...actually two thoughts..
First, make a push shoe...spread the downward force..better control
Second, convert the plate that came with the saw to a zero clearance...it fits already. I believe the idea was in FWW about a year or so ago. Just fit a 3/8" thick piece of stock to the underside and fill the mouth with epoxy.
Always open fo r suggestions. If i were using one like you posted,i might not have had this happen. thanks for your input chris
Chris,
Hope you're OK.
I have a 0 clearance insert from the local tool (toy) store. Fits my Powermatic nicely. I also have the basic insert and dato insert that came with the saw.
My Grandfather made them from 3/8 maple plywood. Lasted for years. In fact they're still around and he died in 1958. They screwed down to the tabletop of his old Craftsman saw. I used them for years on his old saw before getting my Powermatic.
I also had a sers10" until two yrs ago I put it out to pasture,used up!
I also had an accident with the insert coming out because i was not paying attention and didn't think that a leveling set screw too low would hurt. I'll fix it later i told my self.put it off till tomorrow.
So I was crosscutting with the arbor tilted 45 deg..The insert tilted down and caught the blade and threw the insert over my left shoulder and took a chunk of concrete out of the wall. I was slightly shook up when i looked at my left arm and it had spots of blood from my shoulder to my wrist, just likea pin prick if you know what i mean.Then the brand new Freud blade was looked at and determined it to be junk. 35 teeth missing.And believe it or not i was not wearing safety glasses!I think some body was looking over me.The next day i drilled and tapped the saw , insert for 10-24 flat hd screws. Always uses it like that ,with the screws holding the insert in till i retired the saw. Chris
Dear C,
Glad that you are OK! What Blade is that in the picture?
Best,
John
I use a insert made of red oak as well on my unisaw. It is 1/2 inch thick, has four leveling set-screws and a fifth that catches under the back end to prevent the guard from lifting. I have not had any problems, however, I sealed mine with poly to minimize movement of the wood. As well, when cutting the kerf I used rare earth magnets, one on the front and one on the back of the insert, overlapping the cast iron - then raised the blade slowly. I used a 71/4 inch circular saw blade to start the cut, then switched to a 10 inch to finish. Glad you are alright. I will check my insert for damage or cracks.
Edited 2/16/2007 7:58 am ET by Barrel
Dear Barrel,
Thanks for the info. I would stay away from Red Oak as it does move and it does have a bit of a habit of exploding from time to time. Again, glad that you are OK.Best,John
That is a Forest rip blade . Chris
Glad to hear you weren't hurt. How long is the opening on your saw table? I ordered three zero-clearance inserts a while back and while they assured me that they would fit, they don't- my insert is larger. If they're the same size as what you need, they'll be cheap. They're phenolic and pretty dense, with a steel pin at the rear to hold it down.
I'll get back to you with the size of mine Chris
The length of the opening is 14.462 on mine. Chris
"This is what happens when you use not the best of materials for a table saw insert." I'd be surprised if the material was the source of the accident. Sounds more like it was the fact that the insert wasn't solid in the opening. Your last post bears this out, no?
I will say, though, your post is motivating me to get inserts anchored at the back, which I've been lazy about.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
34515.10 in reply to 34515.1
"This is what happens when you use not the best of materials for a table saw insert." I'd be surprised if the material was the source of the accident. Sounds more like it was the fact that the insert wasn't solid in the opening. Your last post bears this out, no?
I said that because a piece of phenolic would mot have split in two like the red oak did .The fit was fine its just that there is no rear support.I will post a pic later on this evening Chris
To keep the insert down at the back, I use a fender washer and a wood screw from the underside. The screw goes close to the back edge, so the fender washer extends past the edge by almost 3/8".
Of course, doing this assumes that the back edge of the opening is conducive...... If not maybe the same could be done either with a countersink, or with spacers.
Support our Troops. Bring them home. Now.
Well. Another great idaa thanks for the input. Too bad PM didn't think of it!
Chris
Chris, I just set up two saws and found the inserts from Lee Mfg. (I think) at Woodcraft -on sale and at LV -no relation- at the better retail price. they have leveling set screws and the lock down pin at the head end. The are also pre kerfed underneath for left or right tilt blade spacing. I just didn't have the time to fuss with making my own and they are very good. I run thin kerf on the LT heavy contractor saw and std. kerf on the RT Unisaw and have a pair with a ½" dado precut for each saw. I also picked up (I hit the sale) two spares for future odd dados that might turn into frequent repeaters. Good luck, Paddy
I'll check them out but right now i'am working on supporting the out board end of insert. See pics at Keith Newton post Thanks for the input Chris
Perhaps a bit off subject, or rather tangent to, but I have a Wood Dynamics throat plate in my PM 66 at home and, because I liked it so much, got the folks at work to spring for one for the PM 66 there as well.
A bit pricey at initial outlay, but comparable with other replaceable insert throat plates out there (about $100), the WD's big advantage is that one can easily mass produce blank inserts out of whatever material one wishes. The factory inserts provided (3) are red oak, I made my first batch out of same. Will probably use poplar next time.
Looking at the prices other manufacturers charge for their replacement inserts, and having used a zero clearance for long enough to realize that even with careful use, they eventually wear to the point of no longer being true zero clearance, I can recommend this system wholheartedly. I have a whole range of dado sizes and blade angles ready to slip in as well as several blanks ready for replacing a worn insert or for creating an odd, seldom used configuration.
RDNZL : Who sells this Wood Dynamics throat Plate? Sounds similar to the one Mapleman suggested Tru cut i think. The only problem with a store bought one is that it does not solve the possibility of insert tipping down on the out feed end of insert unless i attached a block to rest on boss as i menitioned in post to newton( i think, there were two pics posted there ).I do like the idea of replacable inserts though.
Normanly i think there would probably never be possibility of insert tipping but i was putting a fair amount of pressure on this small piece of wood 3"x3"x1/2" thick.and maintaining that pressure until piece of wood completely exited blade.
Thanks for your input !Chris
I got mine with the used saw I bought. I was impressed. Got the one for my employers (and primarily, ME!) by Googling Wood Dynamics, and ordering direct from them. Available in several configurations for different saws. Decent web site, and excellent service. Check 'em out.
I just checked, and yes, my throat plate will tip if pressure is applied within about 2-3 inches of the outfeed end, (indeed this is how I go about removing it) but I have never had it happen while in actual use.
Not exactly sure why one would need to be exerting that kind of pressure in that particular spot in a sawing situation.... perhaps you need to file that one away as "I'll never do THAT again!
RDNZL Guess what? I went to wood dynamics and they show one for a pm66 on their homepage but when you go to models it is not available.May be they are tempory out of stock. http://www.wooddynamics.com/models.html
Any way it looks prety neat . How is that strip of wood held in ? thanks Chris
Sorry to hear it is currently unavailable. If you can find a phone #, might be worth a call to see what's up.
The inserts are 1/4 thick x 1 11/16 wide, beveled 30 deg. (I think). wider at the bottom, narrower at the top, and they simply slide in from either end of the removed throat plate. The ends are radiused to match the end radius of the (aluminum) throat plate, effectively eliminating any front to back movement when installed in the saw.
I saved one of the 3 provided inserts to use as a pattern, and use a top bearing trim bit in a router to duplicate the radius on my shop made inserts. Seasonal movement can result in too tight a fit, but either sandpaper or judicious planing will correct this, and a bit of wax helps as well.
Good luck!
My TS is the craftsman hybrid. I made my zero-clearance from 1/2 mdf using a pattern cutting router bit. I used the pin on the outfeed side like the original and a setting screw on one of the in-feed side ledges (?) which is tapped to accept the screw.
Sounds like a good setup with the pin in the out feed side,, glad to hear that craftsman addressed it.. I'am not a big fan of using the mdf though.i would be afraid of it breaking too easy,The less number of pieces flying out the better. Thanks for your input Chris
Because of your picture, you and everyone else is focusing on the insert as the cause of the kickback, not that it was the result of the kickback. Because you did not provide very many details, my suppositions may not be correct, but here is something to think about.
You said that your insert, push stick, and a 4” x 4” block of wood flew across the shop. That raised red flags with me right away. First off, I would assume your workpiece was the 4” x 4” wood. This coupled with the fact you were using a push stick to control a low-aspect-ratio workpiece tells me that you had a binding kickback, where the back end of the workpiece came away from the fence and rode up the side of your beveled blade. The low blade height and bevel tilt away from the fence further aggravated the situation.
Your assertion that your pushstick’s downward force pushed down on the back of the insert, while a valid concern, does not fit with the rest of the information. In order for this to happen, your pushstick would have been well past the blade, and therefore, so would your workpiece. If the workpiece was past the blade, the blade couldn’t have kicked it back, and certainly not with enough force to pull the pushstick out of your hand.
So to the contrary, your workpiece was still in contact with the blade, and the majority of your down force was forward of the support tabs (ears), not behind. Now what could have also been a contributor to this is the position of the fence right along the edge of your throat opening. As the back of the workpiece came to the back of the throat opening, it could have caught the sharp edge of the tabletop and followed the curve of the throat opening, pushing it sideways into the blade.
Oh, I almost forgot, but the reason why your insert shattered is because the blade was bent sideways during the binding, and it impacted the insert.
If you want to avoid this in the future, avoid making cuts with a low aspect ratio (squares/crosscuts) with out some other type of control such as a miter gauge. Secondly, when you do make these cuts, don’t use a push stick without some other type of control to keep the workpiece tight to the fence. And most importantly, raise your blade a little higher than it is here.
RickChristopherson: Thank you for your in put on what caused this kick back.
Because of your picture, you and everyone else is focusing on the insert as the cause of the kickback, not that it was the result of the kickback. Because you did not provide very many details, my suppositions may not be correct, but here is something to think about.
What other details could i add? This happens so fast there is hardly time to react much less remember every thing that happened ..I see your point about the kick back resulted in the insert fling out. The reason for concern /"focus" on the insert is that it is one part that CAN be controlled NOT to fly out by using screws or what ever .AS you point out the real importance is the Cause of the kickback! So then the question is what caused the kickback? I don't have the answer for that. but it surely lies with the operator ME.I agree with you that the piece of wood was really too small to saw it between the blade and fence.
You said that your insert, push stick, and a 4” x 4” block of wood flew across the shop. That raised red flags with me right away. First off, I would assume your workpiece was the 4” x 4” wood. This coupled with the fact you were using a push stick to control a low-aspect-ratio workpiece tells me that you had a binding kickback, where the back end of the workpiece came away from the fence and rode up the side of your beveled blade. The low blade height and bevel tilt away from the fence further aggravated the situation.
The piece of wood was 3x3x1/2" Thick Haven't been able to find it yet. The blade was 90 deg . You might have read of my other accident in post #17 , which is a whole other story of a sears saw.
Your assertion that your pushstick’s downward force pushed down on the back of the insert, while a valid concern, does not fit with the rest of the information. In order for this to happen, your pushstick would have been well past the blade, and therefore, so would your workpiece. If the workpiece was past the blade, the blade couldn’t have kicked it back, and certainly not with enough force to pull the pushstick out of your hand.
You are probably right here also,although the blade is about one inch past the last ear. The reason i had concern of any condition in which a insert can tilt is because of the accident in had in post # 17 which was a sears saw .
So to the contrary, your workpiece was still in contact with the blade, and the majority of your down force was forward of the support tabs (ears), not behind. Now what could have also been a contributor to this is the position of the fence right along the edge of your throat opening. As the back of the workpiece came to the back of the throat opening, it could have caught the sharp edge of the tabletop and followed the curve of the throat opening, pushing it sideways into the blade.
Don't think this was cause as the wood insert was a little bit proud of saw top.About .002 /.003
Oh, I almost forgot, but the reason why your insert shattered is because the blade was bent sideways during the binding, and it impacted the insert.
Think you are 100% correct here.Therefore this might not have been thrown out if it was a factory insert with clearance on each side of the blade ?A good reason not to use a zero clearance insert??
If you want to avoid this in the future, avoid making cuts with a low aspect ratio (squares/crosscuts) with out some other type of control such as a miter gauge. Secondly, when you do make these cuts, don’t use a push stick without some other type of control to keep the workpiece tight to the fence. And most importantly, raise your blade a little higher than it is here.
I probably should have used radial arm saw .Kick backs are hard to identifybecause there is no nevidence left.behind. but surely ME the operator is at fault .I still feel that the insert flying out is going to be one of the first things i address., there is no excuse for this . .. . I do know that i was exiting the out feed side of the blade when this happened.
Your input has been greatly appreciated Chris Miller
Had your accident occurred with the factory throat plate, your blade would still have deflected sideways, only it would have struck a steel throat plate instead of wood. I wouldn’t be kicking yourself about your wooden insert. I don’t use a zero-clearance insert, but I do have a similar wooden insert for my dado blade. The danger of any throat plate is that is can lift at the back end, not that it can lift at the front. Your factory throat plate can also be pushed down at the rear (e.g. lifted out from the front).
When I made my throat plate, I inserted an #8-32 screw into the wood and then cut off the head. This is in the same position as the little nib on the back of the factory throat plate.
Actually, most kickbacks do leave evidence behind. The saw blade marks on the workpiece are generally enough to figure out the cause. In your case, I would also examine the presumed gouges in the throat plate.
No, I didn’t assume the blade was tilted because of your previous accident, it actually looks tilted slightly in the picture (my mistake).
No, the blade is not past the last support tab. You are looking at the whole diameter of the blade, not the portion above the tabletop. As I said previously, the danger isn’t when the front of the throat plate rises, it is when the rear of the throat plate rises. This is why factory throat plates lift out from the front.
I will use the tablesaw to make some very dangerous cuts that most woodworkers would cringe at, but my nerves would have be on edge making a 3x3 cut. You are correct that the RAS would have been the better tool. With a piece this small, the rotational forces are so high that it is an almost guaranteed kickback.
RickChristopherson <!----><!---->
2:22 am
To:
cmiller231 <!----><!---->
(33 of 35)
34515.33 in reply to 34515.32
Had your accident occurred with the factory throat plate, your blade would still have deflected sideways, only it would have struck a steel throat plate instead of wood. I wouldn’t be kicking yourself about your wooden insert. I don’t use a zero-clearance insert, but I do have a similar wooden insert for my dado blade. The danger of any throat plate is that is can lift at the back end, not that it can lift at the front. Your factory throat plate can also be pushed down at the rear (e.g. lifted out from the front).
Thats just my point ,why are they designed to lift at all from the back .. a screw and a boss if it were there would do it.
When I made my throat plate, I inserted an #8-32 screw into the wood and then cut off the head. This is in the same position as the little nib on the back of the factory throat plate.
Actually, most kickbacks do leave evidence behind. The saw blade marks on the workpiece are generally enough to figure out the cause. In your case, I would also examine the presumed gouges in the throat plate.
No, I didn’t assume the blade was tilted because of your previous accident, it actually looks tilted slightly in the picture (my mistake).
No, the blade is not past the last support tab. You are looking at the whole diameter of the blade, not the portion above the tabletop. As I said previously, the danger isn’t when the front of the throat plate rises, it is when the rear of the throat plate rises. This is why factory throat plates lift out from the front.
You mean they are made to tilt down in the back for easier removal??
I will use the tablesaw to make some very dangerous cuts that most woodworkers would cringe at, but my nerves would have be on edge making a 3x3 cut. You are correct that the RAS would have been the better tool. With a piece this small, the rotational forces are so high that it is an almost guaranteed kickback.
View Image Options
Glad to know you are OK! I went to a plastic supplier and bought an offcut from a sheet of bank guard stuff, the sort you can hit with a hammer without damage. I am going to replace the blade top guard with one made from that stuff so I can better see the cut.
You were using a top guard I suppose. I certainly would not go near those long fences you show, I am keen to remain undamaged, physically anyway.
Was that lexan ? how much did they charge you ?.plastics are pretty expensive around here.Uhmw is the cheapest. Chris
They are costly here Chris, and I have to work hard at my old geeser ploy to get bargains. The trade name of my bit is AXXIS-PC so it is polycarbonate. It measured 23ins by 27ins and cost me £20 which was about one third of the true cost, but it is an offcut and I did explain that I will cut it up into small bits and so will not be doing a Ned Kelly and making body armour.
You younger folk need to organize a "rent a Fogey" group whereby you borrow from an old peoples home to do your shopping in return for ice cream or the like. There is nothing like incontinence in a customer to encourage a sales person to make for himself or her a bad deal.
Chris,
I have a General contractors saw. I actually did what you suggested in your last sentence. I drilled and tapped (4)10-32 holes into the lips that support the plate. I offset the holes from the normal locations because the stock plate has bosses on the bottom to locate the height of the plate flush with the top. I only use them when I have a zero clearance insert in place. Generally make mine out of Hickory, with wax as the finish. No problems. I might suggest you e-mail John White. He seems to have a ton of good experience, and may have a good suggestion or 2
Bill
Magnus
"Remember, a bad carpenter always blames his tools" -Joe Conti-
34515.40 in reply to 34515.1
Chris,
I have a General contractors saw. I actually did what you suggested in your last sentence. I drilled and tapped (4)10-32 holes into the lips that support the plate. I offset the holes from the normal locations because the stock plate has bosses on the bottom to locate the height of the plate flush with the top. I only use them when I have a zero clearance insert in place. Generally make mine out of Hickory, with wax as the finish. No problems. I might suggest you e-mail John White. He seems to have a ton of good experience, and may have a good suggestion or 2
Bill
Magnus
"RememberBill Thats exactly what i did to my old sears after i had a worse accident with it( post 17),I used two in it but four would have been better,like you did.I'll probably do screws in this saw .I just got the saw new two yrs ago and i hesitated to start drilling and tapping holes but you know what they say if you are bit by the same dog twice. Thanks Chris
I made my iserts from laminate flooring and use a 7-1/4" saw blade to start the cut.
This forum post is now archived. Commenting has been disabled