Zero Clearance Insert Problem
Can I use a Circular Saw blade in my table saw to cut a zero clearance insert? My regular blade is too large and the blade doesn’t retract far enough down into the saw. The circ blade will fit in the saw to cut the insert, and it is labeled 9400 rpm – faster than my table saw speed.
Short answer yes I do it all the time.
My prefered way to make the relief cut on the back of the insert is to use a 3/8" core box bit in my router table. Set up stop blocks, make a plunge cut, route between the blocks and your done.Work Safe, Count to 10 when your done for the day !!
Brian, Fit the circular saw blade to the table saw, lower the blade all the way, put the uncut insert into the blade throat, clamp it down by placing a 2x4 over it with clamps at both ends. Turn the saw on and raise the blade most of the way. Turn off the saw, unclamp and replace the circular saw blade with the regular blade. Lower the blade as far as you can get it to go. Put the partially-cut insert back in. You might need to press-fit it down on the small amount of blade sticking through the throat. Reclamp with the 2x4 and raise the blade all the way to finish cutting the insert. Rich
Of course you can use your regular blade, but under NO circumstances try dropping on to cut anything. Instead clamp a large sheet of your insert material over the blade, packed high enough with scrap to just clear the blade in the lowest position. Then start the saw and raise the blade to give an opening of the right length. Relocate the sheet two or three times to enable the making of spare inserts.
All you then do is, before removing the original insert, stick cardboard on top to narrow the slot and so emulate zero clearance and then use it as a template in cutting the rest. Good luck.
It could be done with a circular saw blade but that will undoubtedly be thinner kerf than the one you normally use on the table saw. If you look at the bottom of many zero clearance inserts, they have an area that was removed with a dado and I would recommend doing the same. Use a single blade from the dado set and raise it until it has cut for about one full revolution of the blade height wheel. Remove the dado blade and install the one you normally use. If you're making several, just repeat and/or use more than one dado blade, depending on the use of the inserts (smaller dado, tilted blade cuts, thin kerf, etc).
As the others said, clamp a board over the insert before trying to raise the blade into it.
Just got through doing what Rich described. The problem with a circular blade doing it IMO, is that it has a smaller diameter. Fully raised it is not going to cut the blade slot long enough for the standard 10" blade. If you do raise the 10", it will finish the cut. But the noise of that blade hitting hard phenolic when you don't expect it could cause a jerk of reaction that might require changing pants! ha.. ha...
And be sure to clamp those boards across the insert edges on both front and rear, unless you enjoy watching TS inserts launched to who knows where!
Also.. as already pointed out, if you use a TK blade to cut it.. you're going to have to widen it with a standard kerf latter. Better to just use a standard blade which the TK fits through with no problem to begin with and kill two birds with one stone.
Well... unless you're like "rich" like Rich and can afford a Hammer and two separate inserts for TK and standard. ha.. ha...
PS.. just Sunday harassment Rich between task in the shop... :>)
I keep seeing this come up, so I feel inclined to ask. What brand of saw doesn't let the blade go all the way down under the insert? I have a pm66 and had a sears contractor before that and have never run into that. Seems quite dangerous to me. Just curious,
It's a Jet 10" Xacta Saw (10XL) - cabinet saw, 3HP. My original Jet contractor saw didn't have this problem so I was a bit surprised by this as well.
I have a Craftsman not-so-portable contractor saw that has this problem. A 10" blade will go below the table surface, but jut barely. My zero clearance insert is about 1/2" thick and the blade won't spin freely with that extra thickness. I just use one cutter from a dado to cut the starter hole. Like everyone says, clamp a piece of scrap on top of the insert when cutting the slot.Good luck.
Have you checked the vertical elevation stop is it adjustable to let the blade go down further?
Anderson has the right & safe idea for making the initial cut into your ZCI.
Also another thing you can do is run you ZCI over a router table or the router over the insert with a 1/4" or 1/2" bit & make a slot where your blade will come up through. I have done this for other Table-saws & it works great. I usually left between 1/8" & 5/16" of the material for the blade to come up through.
Edited 2/28/2007 12:58 am by OB
Thank you for the great info - these are all good tips and appear to be very safe as well. Now I just need time to make up a new set of inserts to try out the technique!
Before BYU answered my answer woud have been, "I don't have a clue". I was not aware the Jet wouldn't allow the blade to hide in the table. If someone told me designed one that way... my first question would probably be "Why'?
I see no Jet TS's in my immediate future! ha.. ha...
Yep, terrible design flaw.Rich
I see no Jet TS's in my immediate future!
Me either! I have a jet 6" jointer from about 1994. Not bad, but not really great stuff either. My next jointer is a 12" (or better if I can find some good 'ol used iron close enough to ship without breaking the bank)
The Jet does allow the top of the 10" blade to sink below the level of the table top, just not below the bottom edge of the insert. That seems to be the case with a number of table saws, but it's not really unsafe (unless you are somebody who realizes that the whole tablesaw concept can be considered unsafe). But it's also not really a problem: how often do you have to cut slots in zero-clearance inserts? Not very often, I bet. Some woodworkers use the single dado blade to start the cut and then move to the 10". Some fasten the new, uncut insert on top of the regular insert with a couple pieces of double-stick tape, clamp the whole sandwich down with a board and then raise the running blade through the regular insert and up into the zci. You can also use a straight router bit in your router table to gouge out a slot deep enough for the insert to clear the top of the blade and cut the slot. A minor inconvenience, but not a frequent one.
My Delta won't drop down enough either. I have some 9 inch blades from my old saw and I used one of them to cut the first slot in the insert and then swapped back to the 10 inch blade. I was sort of surprised that this was an issue too.
I have a Delta 36-979 Contractor Saw and with a Forrest WWII blade it will not lower thew blade far enough to place the ZCI in the hole, but with a Freud blade, there is plenty of clearance. I just use one of my dado blades to get the insert started.Larry W.
The way I do it. I crank my blade down to the lowest level. I unscrew the levelers on my normal table throat insert down so it is sunk below the surface of the table. I lay the new insert over the old insert. I clamp a piece of wood over the new insert to hold it in place and raise my blade while the saw is turned on cutting a kerf in the new insert. This give me clearance that I can now remove the old insert, put in the new (with the blade down) insert, move the fence over the insert and raise the blade while its running. Voila!! a perfectly cut kerf in the new insert.
It works for me ...
Barry in WV
I just went through the same problem with my home built insert. I made mine out of a white cutting board. To solve the problem, I ran the bottom of the insert across a 1/4 straight cutting router bit deep enough to clear the saw blade. Don't go any deeper than you need to.
I've been wondering about those white cutting boards. How's the insert working out so far?"Light the lamp, not the rat! Light the lamp, not the rat!!"
Rizzo the Rat, A Muppet Christmas Carol
I haven't finished it yet. Right now it is held in place by a single screw. I'd like at least one more, which means I have to drill and tap in a new one. After I cut out my insert shape, I discovered that the cutting board was warped. We'll see how well it performs. I may need to buy my wife a better cutting board next time. I also made a zero clearance insert for my compound miter saw for plumb cuts only. My cutting board was too thick to fit in the bed, so I had to plane it down. No apparent damage to the knives.
Instead of planing the insert down rout the edge in about 1/4" & to a thickness that will allow it to set down into the opening. This makes for a much stronger insert. Some people are using UHMW or HDPE or some sort of plastic for a ZCTP I don't know how this type of material will work with hand tools to carve out a shallow slot to clear the blade path so the blade can make its initial entry into the material safely.
A while back I purchased a cutting board from ACE for about $18 it made either 6 or 7 ZCTP I drilled & installed allen screws to level the plate no need to pre-thread the plate. I drilled & installed a rolled pin at the back end to go from the plate under the edge of the table top to hold the plate down. The cost of each plate was just a few cents over 3.00.
You can also put a screw in the front edge that you can back out just enough to hold the plate tight to the back of the opening if you plate is a little loose. My plates tend to be reasonably tight so I don't need this.Good, better, best never let it rest until your good is better & your better best.
I just put the new insert on top of the old insert, turn them over and mark with a pencil where the slot will be (on the bottom of the new insert) and then take a 1/4" carving gouge and remove enough wood to accommodate the blade.
Put the Fence over the insert as far as you can, avoiding where the blade will pierce the insert, turn it on and raise the blade. Done, takes 5 minutes.
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