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Joint for plywood cabinet

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Forum topic by daddywoofdawg posted 12-07-2017 05:03 AM 756 views 0 times favorited 14 replies Add to Favorites Watch
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daddywoofdawg

1028 posts in 1772 days


12-07-2017 05:03 AM

Topic tags/keywords: question joining

I’m building a shop cabinet to go under the table saw wing for sled,blades and other table saw stuff,I’m building out of BB ply,what is the best Joint for plywood cabinet? I thought about finger joints and would really think they would look sharp in this app but I can’t see how a person could hold upright a 24” x 30” piece of 1/2” ply to run it through the saw, and I don’t have a router style finger jig, So the two i can think of are pocket screws or mitered with splines.there a better ad fairly simple hard to mess up joint that would work?


14 replies so far

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jonah

1910 posts in 3496 days


#1 posted 12-07-2017 05:16 AM

I’d do a rabbet or a simple butt joint with glue and screws, personally.

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AlaskaGuy

4760 posts in 2506 days


#2 posted 12-07-2017 07:47 AM

D

-- Alaskan's for Global warming!

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Woodknack

12430 posts in 2577 days


#3 posted 12-07-2017 08:18 AM

I don’t know the “best” but I know it isn’t going to matter unless you will be kicking it or rolling it down hills. You can butt joint them and they will be strong enough although rabbets help with alignment. So just go with whatever you are comfortable doing and I would add glue either way.

-- Rick M, http://thewoodknack.blogspot.com/

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Loren

10477 posts in 3845 days


#4 posted 12-07-2017 08:40 AM

Tongue and groove can work well. It’s
not too difficult to cut with a table saw.

I use butt joints because it simplifies the
math but it does require some method
of alignment. I used used biscuits and
screws for awhile.

View rwe2156's profile

rwe2156

3163 posts in 1678 days


#5 posted 12-07-2017 04:10 PM

For something like this simple butt joints with glue and trim head screws. Fill the holes you won’t ever see them.

Rabbets would be a bit stronger and help with alignment, if you’re willing to do the extra work.

-- Everything is a prototype thats why its one of a kind!!

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Bill_Steele

450 posts in 1929 days


#6 posted 12-07-2017 04:18 PM

I think a rabbet is a good choice—self aligning, easy to cut, lots of glue surface. If you do not want to see any of the plies—then I would consider a lock miter—self aligning, lots of glue surface.

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bondogaposis

5086 posts in 2548 days


#7 posted 12-07-2017 04:18 PM

I think the fingers would break really easy in plywood, unless they were quite wide. I honestly don.t feel you’d get much for your effort. I generally use butt joints and pockets screws for plywood cabs.

-- Bondo Gaposis

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Planeman40

1306 posts in 2958 days


#8 posted 12-07-2017 04:44 PM

“Rabbit” (rebate) joints work well as well as spline joints. I like spline joints as they are easy to cut and easy to glue up. And they are strong.

-- Always remember: It is a mathematical certainty that half the people in this country are below average in intelligence!

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ArtMann

1135 posts in 1013 days


#9 posted 12-07-2017 05:49 PM

I used pocket screws and butt joints in all my shop tables and cabinetry. As best I can remember, that was about 15 years ago. I have heavily used and overloaded those cabinets time and time again. I haven’t seen even a hint of failure. Some people say they are weak but you can use as many screws as necessary. The joint can easily be made stronger than dado and glue. The one thing you need to remember is that when you go to assembly, you need to have the joint clamped up tight as if you were trying to glue it together. The only reason I don’t use pocket screws a lot more is they aren’t very attractive.

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Rich

3871 posts in 787 days


#10 posted 12-07-2017 05:50 PM

I’m not suggesting that finger joints would be the best choice, but Woodhaven has a portable box joint jig out that attaches to the board, rather than having to move the board across it.

https://www.infinitytools.com/woodhaven-portable-box-joint-jig-for-large-finger-box-joints-4872

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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JBrow

1366 posts in 1117 days


#11 posted 12-08-2017 01:35 AM

daddywoofdawg,

I like to use a dado/rabbet joint when building plywood boxes because the joints eliminate issues with varying thickness of plywood, are self-squaring joints, easy to cut accurately on the table saw, and offer a lot of gluing surface. In ¾” plywood the dados are 3/8” wide x 3/8” deep. The tongues are rabbets that are 5/16” deep and cut to fit the width of the dado. The edges of the tongues are slightly chamfered to aid in assembly. If the joints are all brought together snugly, the box will be square (if the bottom, top, back, sides and face frame are all cut square).

However, I am not sure enough material exists for this type of joint for ½” thick plywood. On ½” plywood the depth of the dado would be ¼” and the length of the mating tongue would be 3/16”.

Since there is so much glue to spread, slow-set glue is needed or assembling the box in steps is necessary; I assemble in steps. For example only the back, top, and the bottom are glued to the one side in the first glue-up. The second glue-up adds the second side. The final glue-up adds the face frame and completes the glue-up. In all glue-ups, the entire box is assembled and clamped even though some joints are unglued. Long-reach curved cauls are helpful in bringing the joints together.

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woodbutcherbynight

5676 posts in 2606 days


#12 posted 12-08-2017 01:53 AM

Butt joint them but cut back a sliver and glue on a piece of wood slightly wider. When the glue dries trim it with a router. Like you would do Formica. The edge then will not show the exposed plys and fill. Not really needed but practice for when you do want it to look nicer with not fancy joinery.

-- Live to tell the stories, they sound better that way.

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jbay

2858 posts in 1096 days


#13 posted 12-08-2017 02:03 AM

Dado, glue and screw.
A butt joint with pocket screws will never be stronger than this.

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MrRon

5190 posts in 3441 days


#14 posted 12-08-2017 05:39 PM

My vote is for a rabbet joint and dados where needed, as for shelves or dividers. It may sound like overkill to some, but to me it’s good practice for when the big job comes around.

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