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Joint for plywood cabinet

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Forum topic by daddywoofdawg posted 12-07-2017 05:03 AM 436 views 0 times favorited 14 replies Add to Favorites Watch
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daddywoofdawg

1022 posts in 1411 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

1455 posts in 3135 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

3647 posts in 2145 days


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

D

-- Alaskan's for Global warming!

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Rick_M

10621 posts in 2216 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.

-- http://thewoodknack.blogspot.com/

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Loren

9626 posts in 3484 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.

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rwe2156

2714 posts in 1317 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

217 posts in 1568 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

4478 posts in 2187 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

1035 posts in 2597 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

686 posts in 652 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

1978 posts in 426 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

-- No matter how much you push the envelope, it'll still be stationery.

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JBrow

1274 posts in 756 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

3644 posts in 2245 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

1856 posts in 735 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.

-- If anyone would like to see my Portfolio, PM me and I would be glad to send you the link.

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MrRon

4492 posts in 3080 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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