Dados for 3/4" birch plywood

When cutting dados for 3/4" plywood, do you make them 3/4" wide (easy setup) or 23/23" wide (PITA setup with shims, etc.)? I want to do a good job but do not want to expend effort unnecessarily.
Thanks, Dick Fitzwell
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My set comes w/ a special plywood chipper - to make the slight undersize of 3/4. It still requires shims to make the fit perfect.

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"Dick Fitzwell" writes:

My Freud set has the necessary chippers to handle that problem on the table saw.
If I'm cutting them with a router, I always use an undersize bit and make a pass in each direction against a fence on each side of the dado.
Had a router get away from me and climb cut when using a full size bit ONCE which obviously screwed up a piece of very expensive wood.
That is the last time that happened.
HTH
--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
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to do a good job you have to expend SOME effort. :) ie. check the thickness of your "3/4" thick ply, and set up the dado to be a good fit with the ACTUAL ply, as opposed to the advertised thickness.
dave
Dick Fitzwell wrote:

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Been away for a while? Haven't seen anything from you. Mark
Bay Area Dave wrote:

wide (PITA setup with shims, etc.)? I want to do a good job

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Hi Mark,
Yes, I was out of town for a while for the holidays. Now I'm busy in the shop, so I'm keeping a low profile here for a bit. Did I miss anything extraordinarily interesting?
dave
Mark wrote:

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Interesting? Uh-huh. Extraordinarily? Nah.....
Bay Area Dave wrote:

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if the joint is going to get glue you want it to slide neatly together. the glue needs a tiny bit of space(a few thousandths)
On Tue, 30 Dec 2003 22:02:33 GMT, "Dick Fitzwell"

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"Dick Fitzwell" wrote ...

I start small then shim to the point where a dado in a scrap fits the way I want it too. Plywood isn't made exactly the size they say it is and can vary from sheet to sheet, especially if you buy cheap plywood. I never trust any measurement, just the fit. What may seem unnecessary effort now will pay off in the end with better craftsmanship.
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Cheers,
Howard
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Try to cut a test piece a little oversize on the width. Find which shim fits in the gap between the test piece and the plywood that is going into the dado. Remove that size shim from the dado. Has anybody with a stacked set tried this??? Mark
Dick Fitzwell wrote:

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Freud's new dial dado for $269 is adjustable in .004 increments. Sounds a bit coarse to me, but what do I know?
dave
Mark wrote:

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What he said. Plus don't scrimp on the length of the test scrap as a short one may fit fine but the longer real piece will not because the plywood is wavy.

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Snug for glued jobs - my setup for the stack dado is to lay the stack on the iron saw top next to a piece of the same plywood the project is coming from. Add shims on the teeth until it's a bit over the ply. Mount the set and test - I get about a 75% fit rate without reshimming.
As you can tell, there was no Starrett dial indicator under my tree! Eric
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Depends on if you want nice, snug fit or a sloppy one. Measure whatever is going in the dado and adjust for that width plus a few thousanths
John
On Tue, 30 Dec 2003 22:02:33 GMT, "Dick Fitzwell"

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"Dick Fitzwell" wrote

rather than make the dado match the ply, consider doing the opposite. Machine a tongue on the edge of the plywood to match whatever size groove seems right for the job and is easy to produce with one pass from a standard router cutter or unshimmed stack dado. This is often less fiddly and more accurate.
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