# edge gluing plywood?



## dbw (Dec 2, 2013)

I am considering edge gluing two pieces of 1/2" Birch Ply. 30" long. Good idea or bad plan?


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## John Smith_inFL (Dec 15, 2017)

what is the project ??
total 60" long by how wide ?
the general populous will always choose not to join if one piece is available.
many factors to consider in edge joining plywood.
boat builders do it all the time with the correct scarf or lap joint.
you will get many questions and suggestions on this question.

.

.


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## HorizontalMike (Jun 3, 2010)

The only thing that I could think of to add to John's joinery suggestion, might be to ask/suggest veneering the entire top after joining both pieces.


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## BobAnderton (Oct 5, 2010)

I've found edge glued plywood to be a surprisingly weak joint. I mean, I expected it to be weak, but I was surprised at how readily it broke at the joint. I use biscuits when I'm edge joining 3/4 birch plywood and the structure of what I'm building will provide structure to the piece and that works pretty well. I think that's a decent tip because then you can make any size piece you need. Now, putting a biscuit in 1/2" ply may be a little tricky and maybe less effective because it will leave just 3/16 on each side of the biscuit. It will be stronger than just edge gluing the ply though. I know people say biscuits don't add strength, but in this case I think it does because you're pretty much down in the weeds on strength with edge gluing plywood.


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## ibewjon (Oct 2, 2010)

Buy a full sheet, or run a spline the length of the joint.


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## Andybb (Sep 30, 2016)

> I am considering edge gluing two pieces of 1/2" Birch Ply. 30" long. Good idea or bad plan?
> 
> - dbw


Bad plan.


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## LeeRoyMan (Feb 23, 2019)

Just depends on what your using it for. I've edge glued all kinds of plywood. Getting ready to glue up 2 pieces for a sub top as we speak. I've done quite a few for cabinet backs, (usually making the seam land on one of the jambs). But doable, depending on what.


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## dbw (Dec 2, 2013)

The pieces are 12" wide X 30" long. I need a piece 17" wide X 30" long. The glue joint will be along the length. this will be the front of a trash can.


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## John Smith_inFL (Dec 15, 2017)

trashcan ?

I would do it - with a spline and TB-III
K.I.S.S. = Don't OverThink It.
.

.


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## Nubsnstubs (Aug 30, 2013)

You could also do tongue and groove. Is this project going to have any frame around the plywood? If it does, dowels, t&g, biscuits, and splines will work just fine as the frame will be what keeps it together. ...........Jerry (in Tucson)


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## rwe2156 (May 7, 2014)

Yes you can do it. I've done it in a pinch finishing a project and needed a back. I hid the joint behind a shelf.

I used Dominoes, but biscuits will work just as well.

With either of those, it is surprising strong.


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## HorizontalMike (Jun 3, 2010)

How about the easiest joint of all,... a half lap joint?


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## shipwright (Sep 27, 2010)

You don't need the strength in your application but I've made many oversize sheets of plywood using an 8-1 scarf joint. With appropriate glue it provides continuous strength. Puzzle joints also work although a little more tricky.

https://www.lumberjocks.com/shipwright/blog/19783


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## farmfromkansas (Jun 16, 2019)

I have used plywood glue joints to make a back for a peninsula cabinet. Used biscuits to add some strength. Came out very even. Had to be very careful handling the piece. about 5' wide.


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## therealSteveN (Oct 29, 2016)

On really long pieces I think I'd do something else, but across 4' joints a T&G joint is surprisingly strong when glued. Anyone who has placed a plywood subfloor, and glued the T&G, then found out they needed to pull it up hours after it went down. Usually with force the plywood shreds at the glue line. That old picture of the glue holding, but the wood near it failing miserably.

So my thought is this and some glue.

If it isn't 3/4" ply, think about a slot cutter. Any of these will get it away from being an end grain, to end grain joint.


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## RichT (Oct 14, 2016)

> If it isn t 3/4" ply, think about a slot cutter. Any of these will get it away from being an end grain, to end grain joint.
> 
> - therealSteveN


The OP specifically said it was 1/2" ply. Regarding end grain, if you understand that plywood has alternating grain in the layers, and that it's symmetrical, then you realize that half of the glue-up will involve long grain to long grain, assuming you orient the face grain in the same direction (and why wouldn't you).


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## rwe2156 (May 7, 2014)

I think he went to buy a sheet of plywood LOL


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## kelvancra (May 4, 2010)

I've edge glued many times, when I couldn't find a stretcher. When I did, I used splines, be it a full length critter or a biscuit one. I have a 30" Susan in my over-the-fridge cabinet suffering that, from when I didn't want to chop up a fresh sheet, and nothing exploded yet.

Almost all my butt joint glue ups using ply were 3/4.


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## therealSteveN (Oct 29, 2016)

> If it isn t 3/4" ply, think about a slot cutter. Any of these will get it away from being an end grain, to end grain joint.
> 
> - therealSteveN
> 
> ...


On the edge of a piece of plywood??? Maybe you engineers have face grain on your plywood edges, none of the rest of us do. Or are you "edge gluing plywood" as the OP titled his thread, on an alternating face grain. You really need to read slower.


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## LeeRoyMan (Feb 23, 2019)

> If it isn t 3/4" ply, think about a slot cutter. Any of these will get it away from being an end grain, to end grain joint.
> 
> - therealSteveN
> 
> ...


He didn't say there was face grain on the edges.


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## therealSteveN (Oct 29, 2016)

" Regarding end grain, if you understand that plywood has alternating grain in the layers, and that it s symmetrical, then you realize that half of the glue-up will involve long grain to long grain, assuming you orient the face grain in the same direction (and why wouldn t you)."

He didn't???? Funny way to preface a thought about the layers of a sheet of plywood then.


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## LeeRoyMan (Feb 23, 2019)

No, he didn't. It's not a funny way if you understand what he said.
If you put 2 pieces together with the *face grain* on the 2 pieces running the same direction then you have the same long grain to long grain orientation of the plywood layers.
If you take the same 2 pieces, and turn the face grain on one 90 degrees, it changes the grain orientation of the plywood layers.
At least that is what I understood.


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## RichT (Oct 14, 2016)

> No, he didn t. It s not a funny way if you understand what he said.
> If you put 2 pieces together with the *face grain* on the 2 pieces running the same direction then you have the same long grain to long grain orientation of the plywood layers.
> If you take the same 2 pieces, and turn the face grain on one 90 degrees, it changes the grain orientation of the plywood layers.
> At least that is what I understood.
> ...


You understood exactly what I was saying. Someone else seems to have trouble keeping up. At no time did I suggest that there was face grain on the edge of the board. I was referring to the *face grain* on the *face* of the board.

I guess it doesn't matter how slow you read if your brain can't keep up.

Think smart, be smart.


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## dbw (Dec 2, 2013)

I edge glued two test pieces approximately 12" long using #20 biscuits. The joint seems to be very strong.


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## therealSteveN (Oct 29, 2016)

> If it isn t 3/4" ply, think about a slot cutter. Any of these will get it away from being an end grain, to end grain joint.
> 
> - therealSteveN
> 
> ...


I am being told I don't understand what you are saying Rich, exactly why do you preface your thought with "Regarding end grain," Splain it to meee….


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## RichT (Oct 14, 2016)

> I am being told I don t understand what you are saying Rich, exactly why do you preface your thought with "Regarding end grain," Splain it to meee….
> 
> - therealSteveN


I said regarding end grain because you suggested that butting up two pieces of plywood would result in an end grain to end grain joint. (remember what you said: "Any of these will get it away from being an end grain, to end grain joint.")

The notion of end grain to end grain doesn't exist with plywood, due to the alternating layers. If you take two pieces of plywood from the same sheet, and butt them end to end with the grain in the face layers in the same direction, you will have long grain joints in every other layer due to the alternating grain direction. The grain on the faces-and alternating layers beneath it-might be end grain to end grain, but the other layers will be long grain to long grain, because they are at right angles to the face.

You get the same effect if you orient them side by side, with the grain in the top layers parallel. In that case the top layers are long grain to long grain, as are every other layer, while the layers in between are end grain to end grain.

Interestingly, if you turn one piece so the direction of the grain on the face of the plywood is at right angles to the other piece, then all of the layers become end grain to long grain, but why would you do that? I'd assume that if someone was butting up two pieces of plywood that they'd want the grain direction to match.

So Steve (assuming that's your real name), I took a great deal of time to "splain" this. Don't pull your usual MO of disappearing when you are proven wrong.

Either prove me wrong, or admit that I'm right.

Also, please note that I did not become rude during this explanation. At no time did I suggest that you read more slowly, comprehend more completely, or insult you in any way. Food for thought.


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