Zero-clearance inserts and Murphy's law

[daninhim]

Okay, here's my problem for the day. I've got a Delta 10" Contractors saw. I've never installed a zero-clearance insert before. I bought a phenolic zero-clearance insert from Rockler and attempted to install it tonight. I removed the old insert, put the new one in place, and then realized that there is no hole for a mounting screw. So I took it over to the drill press.

The hole has to be drilled with two bits. First, I drilled a hole all the way through, for the shaft of the mounting screw from the old insert to go through. Then I pulled out a bigger bit with the intent of only drilling about a quarter inch into the top in order to leave a countersink area for the screw head. Trouble is I had a brand new drill bit AND I should have used a hand drill, because and as soon as it touched the phenolic board it was like a dog going after a chew toy. It ripped right through the existing hole, making a new hole clear through the board and a half inch wide. Thus, the mounting screw has nothing to mount on.

So here are my questions...

1. How safe is it to use a zero clearance insert that's not screwed to the table, only resting in the hole snugly? I'm assuming that's a bad idea, but I notice in the picture at the Rockler link above, there's no mounting screw showing. Is that normal?

2. Is there perhaps some sort of epoxy I can fill the hole with, and then redrill it with a hand drill, correctly?

3. How many of you are going to suggest I just make a new insert out of a piece of wood or an uncut piece of phenolic with a trim but and a router? Because I want to exhaust options 1 and 2 first.

I suppose there's an option 4, which is to drill an even BIGGER countersink hole, big enough to hold a washer.

BTW I already made the cut through the insert, so other than mounting, it's ready to use. But I thought I would check with the forum to see if I should expect the insert to launch out of the table and through the drywall when I turn on the saw.

It's always something...

[Ben H]

You could fill the hole with epoxy, then just start again. But if everything is in alignment. The blade should never touch the insert again. On my JET cabinet saw, I made a ZCI from the blanks that rockler sells. I drilled into the end (edge) of the ZCI, countersunk a small screw that sticks out just a hair. It creates just enough resistance to give me a very snug fit.

[dmoore32]

Mike do not try to use it without a screw in it. I am sure it would come back at you and casue pain.

Drill the hole a little larger and glue a piece of dow rod into the hole after it dries drill your new hole and you will be just fine.

Duane

[SawDuster]

Hi Mike,

I had the same problem the first time I tried to make ZCI. The hole I was left with was 7/16". After scratching my head for an afternoon, I decided to repair my mistake. I used a small half-round file to gently round over the edges of the hole on one side of the insert then repeat the process for the other side. The idea was to have the smallest part of the hole located in the center of the insert preventing my repair from being pulled out of the insert. ( hmmm...does that make sense?) Anyway, I then taped the underside of the insert with painters tape and filled the hole with 5 minute epoxy. I then re-drilled the screw hole and finished with a hand drill and a countersink bit. Good luck.

[daninhim]

Boy, including a woodworking buddy of mine, that makes exactly two votes for dealing with it, two votes for not worrying about it. I think I will err on the side of safety. I like both the dowel and epoxy ideas. And yes, your explanation for the way you shaped the hole makes perfect sense.

[Beechwood Chip]

I think portable saws have screws on the insert so that the insert doesn't fall out when you move them around. The larger saws generally don't. I don't think it has anything to do with the insert popping out while the saw is in use.

When making a ZCI, I clamp a board over the ZCI to hold it down while I raise the blade.

[Dave]

I also have a Delta contractors saw with many of the pre-manufactured inserts for various different blades. I've never screwed them down and, so far, have never had a problem. The back of the insert (up side of the blade) either has a pin or is molded to fit under the saw top. The front of the insert (down side of the blade) is where the screw was located. As long as you have your adjustment screws aligned properly and that back pin is under the top you won't have any problems.

[Vic]

Mike, I make mine all out of 1/2 Baltic Birch. I simply tap a 3/4 inch single (not for a gun) brad into the back side that keeps it from flying out.

Measure the thickness of the table, hammer in the nail so it is just below that and you're done. One the Baltic Birch inserts, I also install four 1/4" wood screws as levelers sand the top to 320 and wax it.

[mikem]

I put a ZCI on my craftsman table saw that had a screw down but the ZCI does not. The ZCI blank for my craftsman had two screws on one side and the front that I eased out until there was absolutely no movement, and took a bit of force to pull out. I also leveled it as well. Then, and only then, I brought the blade through the ZCI. The blank also had a tab on the back also prevents the blade from pulling it out. I am not sure if the blank for the Delta has any of these same features, however if it does and the insert is properly fitted, you may not need the screw.

BTW, once you are satisfied with the fit, put a splitter on it. Microjig makes a few different sets that are easy to install and will make your saw much safer to use.

[Lawrence Brown]

I'm the same as Dave B. The phenolic inserts I get from Rockler have a pin on the back edge which keeps the back from flipping up, and the front edge just has a screw that I adjust to get a snug friction fit. As long as that pin is in the back, I don't think it can go anywhere because the front would be pushed down by the blade if it ever somehow touched it. Is that screw you talk about taking the place of the pin?

On an old cheap saw I had, it also had a screw-down plate. Since I wanted to use those ZCI's, I actually made some brackets for the insert to sit on and drilled a hole in the tabletop for the pin. It was one of those aluminum things, so I didn't care if I messed it up, but it seemed to work pretty well.

[BillN]

Mike:

Take a small square of wax paper. Tape it to the insert where the offending hole is. Turn the insert jelly side down (wax paper on the bottom) Fill up the hole with epoxy. Remove wax paper. Sand it flat. Start over. Any epoxy should work, just give it enough time to fully cure. BTW, it sounds like you didn't have the item clamped on the drill press when the bit dug in. That's a good way to make your dentist richer - but then I do it all the time too!