Dadoes, grooves, and rabbets

[Drick]

Are there any general rules or guidelines or common sense (which I don't have) principles on how deep to make a dado or groove? I would imagine it ties into the thickness of the wood, but how deep is too deep, not deep enough, and just right?

Drick

[Mike]

Drick, I have never seen any published formula for the "correct" amount of depth for a dado. I use 1/2 the material thickness for a strong joint, less if it is simply a channel for sliding a panel into. The main thing is to be sure you have enough glue surface to hold the joint together, or to prevent your panel from falling out. On a project like a bird feeder you can cut a 1/8" deep dado to slide a piece of plexiglass into and it will be plenty strong. If you were building a window you would need more support for the glass, perhaps 3/8"? Base your decision on the type of project as well as the material you are using.

[BobandRick]

I always use 1/2 the material thickness. Why? Just think about how to make the cut list for your materials. If your cutting away 1/2 of the material thickness then your leaving 1/2 of the material thickness right. 1/2 for each side means that to get the shelf size for that cabinet your making 1/2 material thickness X 2 sides = 1 material thickness.

Example: 24" wide cabinet 48" high and 3/4" thickness of material.
3/8 X 2 = 3/4" So the length of shelves are ?? Right 1 material thickness smaller than the 24" width 23 1/4" it is easy to figure out.

That's why I make the depth of cut on all dados, grooves and rabbets 1/2 of the material thickness.