When working with 3/4" plywood how deep should my dado be?

One place says 1/4" for be 1/3 the material just like a tenon is.

another side says 3/8" to be sure you get to the neutrai axis of the joining material or in my case Thickness /2

What do you say?

 

I've always done one half the thickness.

I will also say half thickness unless there is a long unsupported opposite side and the unsupported side is facing down

Like Lew, I've generally followed 1/2 the thickness "rule" with a few exceptions.

Well this joint is 1/4" up and 1/4" in and it form a hanging channel that forms a recessed table area in a gaming table

.

It will be trapped on four sides so for a good joint should be 1/4" up or more?

Edited January 13, 20251 yr by Michael Thuman

Duplicate topic deleted

25 minutes ago, lew said:

Duplicate topic deleted

Much appreciated.

What are you dadoing for?.

I almost do about 1/2 the thickness of the piece as the others do. But if you remember Richard McComus (Alaska Guy, and a few other similar names on other forums) he has built (literally) hundreds of bookcases, book shelves, etc for the school district he used to work for. He always used 1/8" deep dadoes and never had a failure. So I'd say pick a number and don't look back.

14 minutes ago, Fred W. Hargis Jr said:

I almost do about 1/2 the thickness of the piece as the others do. But if you remember Richard McComus (Alaska Guy, and a few other similar names on other forums) he has built (literally) hundreds of bookcases, book shelves, etc for the school district he used to work for. He always used 1/8" deep dadoes and never had a failure. So I'd say pick a number and don't look back.

Reason I ask what is to be dadoed.
 

Plywood for a carcass in a cabinet is one thing , solid pieces in a piece of furniture using solids is another., I think if I remember  Alaska Guy. I think he had a bear in his picture. Guys like Cabinet Guy/man all have there way of building cabinets. Each shop I worked had a different formulas  to get the same results. Some are better and worse than others. Some shops use depth to keep tye math dime. A 1/4 for instance, 

 

Lets keep in mind if you are doing single boxes/commercial  and not custom theses dados will definitely differ.

 

Remember shops may be working with 1/2, 5/8 and 3/4 plywoods, MDF, PB, etc..

Edited January 13, 20251 yr by BillyJack

OK based on all comments it will be T/2 up from the edge of dado and the dado height is T and the dado depth is T/2.

Based on all the comments T/2~3/8"  so I need to modify my cut list now thanks all.

 

I’ve always used the 1/2 rule. 

1/2 okay till you use that inna 1/2 piece and it snaps. Think about that rule,. I’ve seen shops actually use 1/8:, just to indicate where to put the shelf with no doubt. 

Edited January 14, 20251 yr by BillyJack

Are you indicating it's 1/2", Jack? In my case I mean 1/2 the thickness of the piece. So 1/2" piece would get 1/4" dado. I suspect that's what the others mean as well.

I worked at a shop that used 1/2 PB. I’ve seen many pieces buckled before used the cabinet., Be careful with the half rule..

 

I use a 1/4 in my cabinets. Easy to figure as well. 

 

Edited January 14, 20251 yr by BillyJack