PVA glue for butt joints?

[Frank Warta]

I need to build some simple structural frames, and plan to use construction lumber for them. My plan is to glue'n'screw the joints to keep things quick and simple, these may only get used a few times and then tossed so I don't want to invest a lot of time in them if I can avoid it, they'll also be small on 24" square on top.

Anyway, I know there have been a lot of joint/glue tests, and I'm wondering if yellow glue is the clear winner for butt joints like it is for long grain joints? Basically the logic is based on the idea that the gap filling properties of PVA might make it stronger when one of the faces is end grain? Any thougths?

Thanks in advance!

[Mike Henderson]

I haven't had great luck with end grain butt joints. If you can make a half lap joint instead, it'll be a lot stronger.

Mike

[Chip Lindley]

Yellow glue has little holding power for butt joints. It will *stick* them together, but any stress will fracture the joint easily. For quick and dirty butt joints, I would recommend one of the polyurethane glues. I like Elmers poly! Cheaper than Gorilla glue and seems to have TONS of holding power.

[Norman Pyles]

If you are going to use screws, then I would not even bother with any glue. You won't have much holding power gluing end grain. That's why we have all these fancy ways to join wood together, to avoid gluing end grain. :)

[Frank Warta]

Yellow glue has little holding power for butt joints. It will *stick* them together, but any stress will fracture the joint easily. For quick and dirty butt joints, I would recommend one of the polyurethane glues. I like Elmers poly! Cheaper than Gorilla glue and seems to have TONS of holding power.

I actually meant polyurethane, and said PVA on accident. So I'm glad to hear it can be helpful.

I'd considered half lap joints, but I'm looking at something like 96 joints and they've asked if I can have them done by Saturday morning. They were nice enough to say that don't need to be painted yet...=) So even quick and dirty is going to be a stretch at this point. Like I said they only have to hold for a few uses, then they're likely to be tossed, I'm hoping that gluing the "skins" on will make things rigid enough that the joints wont be as important.

[Richard Dragin]

Sounds like scenery, what are you building? Do these have to support weight?

I wouldn't bother to glue the butt joint if you are skinning the structure. Gluing and staples (to hold it till the glue dries) of the skin will give it more strength than the butt joint.

[Joe Scharle]

I suppose you've considered pocket holes? I've built some 2 X 4 frames with 3" screws.

[Dino Drosas]

Can you say Domino?

[Chris Padilla]

Screws...done.

[Mark Woodmark]

I would screw and glue since you may discard them after a few uses

[Lee Schierer]

The strongest end joint I've ever witnessed was glued with the HiPur urethane glue at a wood show. They glued pine pieces end to end and asked the observers to try to break the joint. Many tried none were able.

[Frank Warta]

Thanks for all the info guys!


Sounds like scenery, what are you building? Do these have to support weight?

I wouldn't bother to glue the butt joint if you are skinning the structure. Gluing and staples (to hold it till the glue dries) of the skin will give it more strength than the butt joint.

Not exactly scenery basically really small stage extensions. They are basically 2' cubes, and they will need to support 1 person at a time. I'll obviously risk life and limb myself and give them a little stress testing. I probably weigh at least 40-60 lbs more then any of the people that will be using them for the shows. I figure if I can jump up and down on them with out them falling apart I'm probably safe.

I also figured the skins would provide at least as much support if not more then the joints, but I tend to be a little conservative with things like this. I'd like to do anything I can (that's practical given the deadline) to make these sufficiently strong.


Can you say Domino?Man I wish I could! =) At this point the only tool I think I'm gonna be able to justify to SWMBO is an impact driver for the 3.5" screws. The domino will have to wait I'm afraid. I even considered doing dowels but I don't have enough experience with them to be confident I could have them done quickly enough.

[Richard Dragin]

If you are going to cover them with ply you may be better off skipping the framing and just make boxes. If they are getting paint you could use really inexpensive ply.

[Frank Warta]

If you are going to cover them with ply you may be better off skipping the framing and just make boxes. If they are getting paint you could use really inexpensive ply.

I was worried that a simple ply box wouldn't have the shear strength required, and like I said I tend to be a bit conservative with such things. I don't doubt that decent 3/4 ply and enough glue would probably be fine, especially with some kind of tack strip behind each edge to provide additional glue surface.

[Richard Dragin]

If you build a 2'x2' ply box and cut the top so it sits on top of the sides, you could pretty much park a car on it. I wouldn't even put a bottom on it because it would only make it less likely to sit flat on the stage.

The best and fastest way to assemble it is with an MII staple gun and long staples. Glue won't hurt but it only helps a little. I couldn't begin to count how many things I have built that way for strong temporary stuff.

[Greg Hines, MD]

I actually meant polyurethane, and said PVA on accident. So I'm glad to hear it can be helpful.

I'd considered half lap joints, but I'm looking at something like 96 joints and they've asked if I can have them done by Saturday morning. They were nice enough to say that don't need to be painted yet...=) So even quick and dirty is going to be a stretch at this point. Like I said they only have to hold for a few uses, then they're likely to be tossed, I'm hoping that gluing the "skins" on will make things rigid enough that the joints wont be as important.


I would at least use some pocket screws to shore it up.

Doc