Looking for a dado cutter for my router

[javeryh]

I've got 3/4" cabinet grade plywood and I want to make dado joints for strength and so no light will escape from the inside.  I know 3/4" wood really isnt 3/4" - what size bit should I get?  I measured the thickness and it appeared to be 11/16" but I can't find a bit that size.  Would 23/32" do the job?   

[Mameotron]

Well, it used to be that when you bought 3/4" plywood, it was 3/4" thick.

[lokki]

Funny, I recently discovered that 2X4 are really around 1.5"x3.5" I was a little shocked by this, and thought I had bought the wrong boards for a little while.

[Hiub1]

Width can even vary from sheet to sheet. The best way to get a snug fit is to keep testing every time you buy wood. Get a caliper and measure accordingly, then purchase the bits according to what you measured. If you don't feel like buying more bits you can always do more than 1 pass with a smaller bit, but this requires a lot of careful measuring and time.

[DrewKaree]

If you don't feel like buying more bits you can always do more than 1 pass with a smaller bit, but this requires a lot of careful measuring and time.

Or you can use two pieces of straight edge on either side of your dade, set to the thickness of your piece and clamped down to form a jig.  It should take less than 2 minutes - TOPS.

If you're doing it this way, get a ¹/₂" straight bit.  It's an in pass, move to the other side, and an out pass.  Done.

Look for "plywood bits".  They'll be close enough that the glue will cover any minor gap.  Use Gorilla Glue to REALLY fill the gap.

That's even quicker. 

[Mameotron]

Use Gorilla Glue to REALLY fill the gap.

Absolutely right on.

[DrewKaree]

Ya, but not TOO much.  It'll even spread the clamps apart if you put TOO much in there. _{don't ask how I know that}

[Tailgunner]

Ya, but not TOO much.  It'll even spread the clamps apart if you put TOO much in there. _{don't ask how I know that}

Heh, Gorilla Glue is basically very low expansion polyurethane foam. Concidering how long spray foam cans have had "Caution, non-removable from most surfaces, including you" warnings on them, it's surprising nobody figured out the stuff would make a good glue.

As to how much force the stuff can exert, I've seen the corner of a house lifted off of it's foundation by an overzealous application of spray foam.