Routing Dadoes for Cabinetry (hint: wrong size)

Do you have a 1/2” bit. You can run the dado at that width, then rabbet the tongue to fit that, is one way

Woodwhisperer has a good video on an exact width dado jig.
http://www.youtube.com/watch?v=7j4vGS4HY-8

Its the most versatile option.

I have an undersized 3/4” plywood bit. Even that doesn’t gaurantee a snug fit.
I use the Woodsmith version of the exact width dado jig. It is like the Wood Whisperer jig, except you don’t need a guide bushing. It works very well, and cuts clean dados in plywood. http://www.woodsmithshop.com/download/204/adjustabledadojig.pdf

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

Well, I’m liking the two jigs, though that means I’ll have to go buy another router, which I was hoping to avoid. Both look like versatile solutions, but neither one lets me assemble cabinets tomorrow after a quick trip to my local Rockler or Woodcraft store.

-- There are 10 types of people in the world: those who understand binary, and those who don't.

Why do you need to buy another router? Just grab the one from your router table.
Or maybe get a dado set for the TS?

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

I could do that, I suppose… but the one in the router table is mounted in a lift and it was a PITA to get squeezed in there in the first place. Taking it out again, then putting it back, etc. sounds like the kind of thing that might drive me to drink…

I’ll just tell my wife that you all recommended that I buy a new tool… ;)

-- There are 10 types of people in the world: those who understand binary, and those who don't.

Real Baltic birch comes in metric sizes, so what is commonly called 3/4” is actually 18 mm. If yours measures about 5/8” then it’s probably 15 mm. I second the recommendation for a dado stack—easiest tool to fine tune for a precise fit. Good luck.

-- John, BC, Canada

I cut most of my dados on the TS using a Freud box cutter set and multiple passes to sneak up on a perfect fit.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

If you have patience, you can cut the dados without needing a dado set or a router. Just make multiple passes with your table saw moving the fence with each cut.

-- Jesse, Saint Louis, Missouri

I like the first answer Shane gave you. Route a 1/2” dado and a tongue on the edge of the 3/4” plywood so it fits. Should work out really well for you. The woodwhisperer actually talks about it in a tool cabinet video he did here

So, all of these things are great ideas and I’ll probably implement more than one solution in the future. As it stands now, however, the local Woodcraft sale today sucked me in. I ended up getting a set of 3 Freud plywood bits, along with assorted other whatnots, and put them to use. Turns out that the 23/32” works great, tight fit, etc. That’s on this Birch I have which seems very consistent (was under by 1/32” by the by… I was reading my calipers wrong last night).

Already dry-fitted the carcases and all is tight and great. Spent the next hour laying out my next sheet so I can get enough for two more tops, two shelves, and two backs. That gives me two complete carcases at about 30”High x 28” Wide x 18” Deep. Then to glue, blocking, etc., and then off to start the face frame (probably do pocket screws to join, then biscuits to join face frame to cabinet).

So far everything was almost dead-on square during dry fit. Fingers crossed it stays that way during the whole project. :)

-- There are 10 types of people in the world: those who understand binary, and those who don't.

Or use your 1/2 inch bit for the first cut, then move the fence the appropriate amount to expand the dado to the size you need.

-- "Measure twice, cut once, count fingers"