Making a ZCI for tablesaw

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You know, sometimes the most simplest thing turns into analysis paralysis.
Want to make ZCI insert for my JWTS-10 Jet. I bought a ZCI some time ago and I measured the thickness - 3/8". I measured the one on the JET, same and just for fun, I measured from the leveling flange to the top of the saw 3/8".
However, when I go looking for instructions, most are calling for 1/2" ply or phenolic. The differences in thickness are usually handled by rabbeting the ZCI so it sits flush.
To me, it sounds like 1) another router set up after I already mount the flush bit to trim the blank 2) more time.
Why wouldn't you just use 3/8" ply or phenolic to make a ZCI, trim it, drill for leveling screws and be done? I just don't know why 1/2 material would be that much better?
I've been looking at what's out there for sale in the already made category and Leecraft has a minor sale on at Woodcraft (I think).
Does anyone have a JWTS-10 and purchased a Leecraft ZCI? If so, do they undercut (rabbet) around the edge to fit in the throat? Meaning, is it 1/2" thick?
Cheez, you'd think this would be so easy. Woodcraft has a sale coming up this weekend, so I thought I'd grab the necessary material to "roll my own", but now I'm just caught in my own analysis paralysis. Somebody help me to reboot!
Thanks,
MJ
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On 7/19/10 8:53 PM, snipped-for-privacy@gmail.com wrote:

It is easy and yes, you're thinking too much. Been there and was amazed at how easy it was, after I finally just did it instead of planning it.
I used quality 3/4 Finnish birch plywood, then used a planer to get it down to pefect thickness. http://picasaweb.google.com/mikeadiddle/ZeroClearanceInsert #
Check out this video... http://www.woodsmith.com/issues/146/videos/making-a-zero-clearance-dado-insert / It's a pretty good technique.
--

-MIKE-

"Playing is not something I do at night, it's my function in life"
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I've seen the video before and now caught something that the editor said, he said the ply was "close" to the thickness of his standard insert. Thinner is better, is what he said.
3/4 ply is WAY thicker by double of what I need. What size did you plane down to?
Thanks,
MJ
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On 7/20/10 12:44 AM, snipped-for-privacy@gmail.com wrote:

I have no idea. I'm guessing it's near 1/2. 1/4" is nothing for a planer. Heck, 80 grit paper on a flat board would do the trick in a few minutes with some elbow grease. Just leave the top side untouched to make sure it stays flat.
The bottom doesn't natter much, especially if you're using leveling screws.
If yours is 3/8", you could start with 1/2" and plane/sand down in no time.
--

-MIKE-

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On Mon, 19 Jul 2010 20:16:07 -0600, MIKE- wrote

insert
I used 1/2" oak (Unisaw). 3/8" would have been a bit too thin, The 1/2" needed only a few turns of leveling screws protruding from the bottom to sit flush. I'm using a piece of 1/2" BB ply right now to see if it last longer than the oak (based on some past posts here) and so far so good!
-Bruce
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Wouldn't solid warp? I wouldn't think hardwood would be a good choice in any case.
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On Fri, 23 Jul 2010 15:31:58 -0600, snipped-for-privacy@gmail.com wrote (in article

No warpage, but I did have issues with splintering around the blade slot due to the hammering from the teeth over time. This is why I'm hoping the BB ply is more durable (needs to be more springy).
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wrote:

Just get some 3/8 material: ply, Baltic birch, Plexiglas, phenolic, lexan, melamine covered termite puke, medium density termite puke, aluminium, whatever & go for it. It's not as it needs to bear a lot of weight.
Luigi
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One reason to use thicker material is flatness. 3/8 material, even Baltic is less likely to be as flat as 1/2 or thicker. A twisted insert will be nothing but a pain in the ass. I suppose that is one reason why people use thicker material. Also weight is a consideration. You don't want it to be so light it is flighty or easily upset, you can think of the scenario where it jumps out of the slot and catches the back of the blade and does a quick fly-by of your ear.
Finally, please replace your planer blades after planing ply. Really not a good thing. Glue is super hard and abrasive and probably equal to 100 times as much wood passes.
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Not sure I buy into that... at least not enough to worry about it.
Also, I don't think you can throw around the term "glue" in the general sense when it comes to plywood. The stuff they use isn't exactly carpenters glue, and it's so thin, I suspect it's a non-issue.
In any case, I'll stick to my first statement. :-)
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Exactly what I did with my inserts bit did use 1/2" baltic birch on a JTAS 10L, BUT make it even easier, put the leveling screws on the bottom and you end up with a flat top with out holes for debris to collect in. I have never ever had to readjust the screws after the initial set up.
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Did you rabbett out the bottom to fit? The depth of the leveling flange to the top is 3/8".
MJ
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On 7/20/10 1:33 PM, snipped-for-privacy@gmail.com wrote:

Instead of rabbeting, you could simply drill out sections/recesses for the flanges with an appropriately sized Forstner bit. Even if the flanges are much longer than wide, you could drill side by side holes down to 3/8", leaving 3/8", and clean up the resulting recess with a knife or chisel.
--

-MIKE-

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That's an excellent idea. Much better than resetting the router table. I'm going to try it over the next week.
Thanks for that tip.
MJ
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In my case the depth on the saw is just over 1/2", so no rabbeting.
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An old tip for leveling ZCI I first saw on this newsgroup, but can't remember who to credit: Just put a blob of hot-melt glue at the correct spots on the bottom of the insert, press down into saw so it's just above flush, then hit the blobs with a block plane or sandpaper if necessary.
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plausible, and wrong." (H L Mencken)
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On 7/20/10 4:50 PM, Larry W wrote:

That's an awesome idea. Instead of sanding, I guess I would try using a couple rulers or other straight edges to push it down flush and hold a few seconds while the glue dries.
If it didn't work the first time, you just pop off the hot glue nubs and try again.
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-MIKE-

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Might want to rethink that, it will essentually glue your insert in place. Put the globs of glue on the insert and then sand the globs to proper thickness after they harden.
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On 7/21/10 12:43 AM, Leon wrote:

The hot glue I've always used is pretty easy to pop off.
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Yeah it pops off easy.... but it is glue, right? And you are going to apply it and squeeze it between an insert and the table saw tabs, and then how do you pop it off if it has glued your insert in place?
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