Will a dado 1 1/2" wide 1/4" deep in 1/2" plywood weaken it sufficiently

[George Bokros]

I need to cut a dado in 1/2" ply 1 1/2" wide 1/4" deep. Will this make the piece (~16"wide x 40" long) hard to handle during the build and assembly?

Thoughts and comments?

[Robert Engel]

Umm....."No"....

[Peter Quinn]

Love to know more about the whys? What is the function of the dado? I think that dado will definitely weaken the plywood, thats not that large of a piece of plywood but as part of a larger assembly it could become difficult to manage? Also depends on where the dado falls in the sheet. Edge, middle, length or width. If its for alignment often a spline is less destructive and equally effective.

[George Bokros]

Love to know more about the whys? What is the function of the dado? I think that dado will definitely weaken the plywood, thats not that large of a piece of plywood but as part of a larger assembly it could become difficult to manage? Also depends on where the dado falls in the sheet. Edge, middle, length or width. If its for alignment often a spline is less destructive and equally effective.


The dado is across the 16"width in the middle of the 40" length. It will be in the top and bottom panels of a cabinet that part of a closet organizer system I am building. The dado is to locate and hold a vertical partition in position. Clothes hanging rods will be attached to this panel on both sides.

[Tom Howarth]

If you glue the 1 1/2" boards in the dado, it'll replace the material you cut out. I'd set a couple of screws into it too.

[Doug Garson]

If you are worried why not use a 3/4" dado and rebate the matching panels?

[George Bokros]

If you are worried why not use a 3/4" dado and rebate the matching panels?


What do you mean "rebate the matching panels"? I am not familiar with that term as it applies to woodworking.

[Jim German]

You're removing 50% of the material of the panel, and therefore may reduce the strength of the panel by 50%. If the piece is going to be vertically mounted with solid wood in the dado, then the solid wood will take the load and you won't loose much strength. Its hard to tell from how you have described it, but it sounds like that's not the case though. Do you have a sketch of the design? If I'm picturing it right, you would be making the panel significantly weaker, and the same point where the shear stress is the highest.

I'd rethink your design, or use at least 3/4" ply with a 1/8" dado instead. I wouldn't hang clothes from a 1/2" sheet of ply to begin with.

[Rich Engelhardt]

Hmm - seems to be two camps here.
Camp #1 says the plywood taken out will be replaced by the wood going in.
Camp #2 says the cut is half the thickness and will have a significant impact on the strength.

I'd lean towards camp #1 myself. It may not be 100% as strong, but, it should be close.

Why not try some scrap and bust it apart after it dries a couple days?

[George Bokros]

UPDATE

I made a test dado 1 1/2" wide 1/4" deep in a piece of 1/2" ply and found that I could not break what the play where the dado was. I believe for my purposes it will be strong enough for its intended purpose. I did not even glue the two pieces of 3/4" ply vertically into the dado.

Thanks for all the input and thoughts.

[Doug Garson]

What do you mean "rebate the matching panels"? I am not familiar with that term as it applies to woodworking.
Ok my bad spelling I meant rabbet, same as a dado but along the edge of the panel. Can I blame spellchecker?