Attaching trim to edge of plywood?

Dowels?

Bob Hutchins in central Texas

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Re: Attaching trim to edge of plywood?

Jack Guzman from Maine

>I wouldn't count on glue to hold that Ernie. The band will expand and contract. My not very sophisticated technique is to nail it on.---Jack

Re: Attaching trim to edge of plywood?

Dave (Arlington, VA)

>Hi Ernie -

I'm going to make a few assumptions - so feel free to set me straight if I assume wrong. First, it doesn't look like your trim will be taking much if any structural stress (after all you did say it was "trim"); and second, I'm guessing that you are going to use a natural (i.e. clear) finish (of some kind).

First, I'm not so sure glue alone (even hide glue) will hold up over time since the edge of the plywood is end grain.

Nails and screws would probably work - since there may not be much stress on the trim. I did this with a desk/work station for my oldest son, but since I was painting it I simply chose to use screws (countersunk) and then filled and painted.

Nails also might works - and then you could carefully fill the holes and they would be fine. Another possibility might be something like upholstery tacks (but I'm not sure if you could find them will sufficiently long shafts) - they would look more ornamental - especially with brass heads or some such - maybe you could combine the glue with the tacks. However, I'm not sure if that would complement or conflict with the design effect you are going after here.

For strength you might consider tongue and groove or a spline -- and glue. It would give you something other than end grain on which the glue could adhere. However, I would hate to have you use one of your finely sharpened planes on the plywood - so maybe a router would be the way to go). I considered this for the desk/workstation for my son, but in the end considered it overkill for that particular application - and so far (2 years later) it's looking fine with just the screws.

In any case - just a few thoughts. Good luck.

Regards -

Dave

Re: Attaching trim to edge of plywood?

fmutchler@adelphia.net

>Ernie, this suggestion may be too late but I'll offer it anyway. If you have enough depth to your trim you can cut a 3/4" groove...not a rabbet...in the lower portion of the trim and then glue and insert the 3/4" ply. Then you'd be gluing long grain to long grain and you won't need any other fasteners.

Re: Attaching trim to edge of plywood?

Pam Niedermayer - Austin, TX

>Plywood really doesn't have a grain direction, which is why it's so stable. Granted that the top layer has an apparent grain, but that's only cosmetically useful.

I agree with the rest of your advice.

Pam

Re: Attaching trim to edge of plywood?

Glenn Madsen

> I thought Hand Tools meant no electrons were to be killed in the project!

However, since I'm Reformed, not Orthodox...

Why not bicuits and (weather-resistant)pocket screws from behind/underneath? With a good waterproof type glue, such as Titebond II?

And if you were to spend a bit more for the underlayment, and find, say, a marine-grade, high ply-count product, then the pocket screws would have a stronger edge against which to 'shoulder'.

Glue alone is plenty strong

Scott Post

>Half the edge is long grain so there's plenty of good glue surface. If it'll make you feel better you could use a spline, but that's just extra work.

Re: Attaching trim to edge of plywood?

JL work

>Biscuits or spline.

Re: Attaching trim to edge of plywood?

Don Thompson - Cutler Ridge, Florida

>You did not say what kind of trim (edging) you want to put on the plywood.

I have done this two ways. For thick trim (what I used on the edge of shop tables/benches), I have used biscuits and glue. Up to ten years of testing, no problemo. On shelving, I have used plywood edging tape, heated with an iron to activate the glue. No problems.

Re: Attaching trim to edge of plywood?

Ross Canant

>Glue will hold just fine. If you want a little extra insurance, rabbet the edge of the trim, even 1/8" will add strength. I do this for shelf edging.

Re: Still long (i.e., not end) grain

Dave Mount

>Pam--

I disagree with your disagree. If you use a T&G, spline, or biscuit in this app, you will expose a longitudinal cut through the grain, and therefore a good glue joint. That longitudinal grain may be running at 0 or 90 degrees (within the same plane as the groove/slot) depending on the plies that are exposed in the joint, but it's still good glue surface compared to the end grain, with is roughly 1/2 of a butt joint with ply.

Regards,

Dave

Dave Mount, Two Harbors, MN

Tongue and

Ron

>Cut a tongue on the ply and a groove in the trim piece. have done it may times although I think Scott it right

Re: Still long (i.e., not end) grain

Pam Niedermayer - Austin, TX

>Dave, plywood is by definition made with very thin layers of wood placed in cross grain relationships with each other. That is, long grain is placed 90� (or 270�) to the grain of the adjoining layer(s). The grain alternates direction with every layer. It appears to have a grain direction because the manufacturers place both outside layers with parallel grain. This is why it's so stable vis a vis movement.

Pam

Re: Still long (i.e., not end) grain

Frank D. in Montreal

>Hi Pam,

Good to see you around! Plywood sides are 50% end grain, no matter which side. When you instert a biscuit or spline, they don't contact the sides of the plywood, but a face with 100% long grain (no matter which direction: it's all long grain). Anything glued to a face, even to a face within the plywood like a biscuit, will be glued to long grain only (even though the direction of the long grain may change or cross, it's still long grain).

Frank

Sheeze!

David Miller from Iowa

>Just glue and nail it.

Re: Still long (i.e., not end) grain

Pam Niedermayer - Austin, TX

>Thanks, Frank. I agree that biscuits and/or splines would work, and work in plywood for the same reason they work (after a fashion) in solid wood.

Pam