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plywood carcass construction dado depth

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Forum topic by Belg1960 posted 553 days ago 2027 views 0 times favorited 21 replies Add to Favorites Watch
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Belg1960

786 posts in 1661 days


553 days ago

Topic tags/keywords: question

Guys this is something basic but what depth do most people use when making dados for horizontal shelves/dividers into 3/4 vertical plywood? Thanks Pat

-- ***Pat*** Rookie woodworker looking for an education!!!


21 replies so far

View bluekingfisher's profile

bluekingfisher

989 posts in 1576 days


#1 posted 553 days ago

Pat, usually about half the thickness of the material, therefore 3/8” although 1/4” is suitable for some projects.

I wouldn’t however exceed half the thickness

-- No one plans to fail, they just, just fail to plan

View bondogaposis's profile

bondogaposis

2439 posts in 947 days


#2 posted 553 days ago

I go 1/4”.

-- Bondo Gaposis

View ClayandNancy's profile

ClayandNancy

479 posts in 1611 days


#3 posted 553 days ago

What if you have two dadoes on opposite sides at the same spot? Is 1/4” ok or too much?

View SamuraiSaw's profile

SamuraiSaw

433 posts in 560 days


#4 posted 553 days ago

Agreed on not exceeding half the thickness. A lot depends on the span of the shelf, if there is a back to the cabinet, and the fastening mechanism of the shelf. If you will be using screws to hold the shelf in place or if you will be able to attach the back to the shelf a 1/4 dado will be sufficient. All you’re doing is registering the shelf to the side. If the sides are visible you’ll want to go deeper to provide more stability.

-- Artisan Woodworks of Texas.... www.awwtx.com

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1755 days


#5 posted 553 days ago

I normally do 3/8”, but beware that 3/4” plywood is not necessarily 3/4” .

-- jay, www.allaboutastro.com

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Cosmicsniper

2199 posts in 1755 days


#6 posted 553 days ago

@ClayandNancy – I would use a 3/16” dado in that situation, likely also mounting it in a face frame or edge banding.

-- jay, www.allaboutastro.com

View JesseTutt's profile

JesseTutt

795 posts in 707 days


#7 posted 553 days ago

I tend to use about 1/4 to 1/3 the thickness of the material, so I would normally use 1/4 dado on 3/4 plywood. I would use less if I had a dado at the same location on the opposite side.

-- Jesse, Saint Louis, Missouri

View Gene Howe's profile

Gene Howe

5375 posts in 2025 days


#8 posted 553 days ago

As SamuraiSaw said, it depends on the application. However, with today’s glues, 1/4” is sufficient for MOST applications. It’s the span and prospective weight on the shelf that deserve consideration. The actual joint will be strong and solid.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

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Cosmicsniper

2199 posts in 1755 days


#9 posted 553 days ago

@Gene – I’m trying to think when you’d even need glue (from a structural standpoint), especially if there’s a face frame and cabinet back to lock it in? To me, I often just glue it in to make sure it doesn’t shift around and rattle over time.

-- jay, www.allaboutastro.com

View SamuraiSaw's profile

SamuraiSaw

433 posts in 560 days


#10 posted 553 days ago

I always glue shelves/partitions in place to provide additional stability. I’ve never had a customer complain because I over-engineered a piece, but I have certainly regretted the opposite when (and invariably it will) a joint fails and I have to repair it.

-- Artisan Woodworks of Texas.... www.awwtx.com

View Belg1960's profile

Belg1960

786 posts in 1661 days


#11 posted 553 days ago

The span on the two units is only 20” and it will have a back of either 1/4 or 1/2 material probably luan ply.
Another thought I’m using unfinished ply to build these but decent quality material, to hand finish it would most of you assemble first, or prefinish large sections and then machine them? And assemble after?
For the smaller cabinet like this I think the 1/4” will do, for the dado. Never thought about the situation where 2 dados would be at the same height but not in this case. Thanks much

-- ***Pat*** Rookie woodworker looking for an education!!!

View SamuraiSaw's profile

SamuraiSaw

433 posts in 560 days


#12 posted 553 days ago

If it is stain grade, I tend to machine the parts, apply stain, then assemble and top coat. That helps prevent problems with glue interfering with the stain. If paint grade, do the complete assembly then finish.

-- Artisan Woodworks of Texas.... www.awwtx.com

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1755 days


#13 posted 553 days ago

@Samurai – I’m not suggesting that you could always leave this joint unglued. I wouldn’t. I was thinking more in terms of a shelf/divider (see OP) as opposed to the cabinet box itself. I should have clarified that.

-- jay, www.allaboutastro.com

View SamuraiSaw's profile

SamuraiSaw

433 posts in 560 days


#14 posted 553 days ago

Cosmic, I tend to over-engineer stuff. My theory is if you can’t park a car on it, beef it up!!!

-- Artisan Woodworks of Texas.... www.awwtx.com

View bondogaposis's profile

bondogaposis

2439 posts in 947 days


#15 posted 553 days ago

What if you have two dadoes on opposite sides at the same spot? Is 1/4” ok or too much?

In that case I’d go 1/8”.

-- Bondo Gaposis

showing 1 through 15 of 21 replies

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