Join two pieces of plywood end-to-end? Best joint?

[Chris]

Hi,

I'm a real newbie but I think I can do this. I'm making a desktop out of oak plywood (probably 3/4"). I don't think I can get a ten foot piece of plywood so I will maybe have to join two pieces (I haven't been to the lumber store yet). If I do need to, what's the best joint to use. I've been reading about biscuits (not too good I think) and splines and draw bolts. What's a good method to keep the joint solid and resistant to separating bearing in mind that dovetails might be out of my league a bit :)

Thanks,

Chris

[Dan]

Your can get 10' long plywood and for that matter veneer if you want. Just sho around. In my opinion, it would be better than having a seem.

[Dave W]

This is done all the time in boatbuilding. Scarf joints are the most often used. I would recommend thinking hard before ordering a long sheet. A friend ordered a 16 foot sheet of plywood, at great expense, it had to be picked-up at the distributor. He found that it could not be carried on his station wagon. He went to the nearest hardware store, bought a handsaw, got the two pieces home and learned how to make a nice scarf joint. Dave

[Rob]

I have seen router bits that are designed to edge join plywood together.

Look around and I'm sure you can find a set.

Rob

[Jim K]

I agree that a scarf joint would be best, but another option would be to cut to grooves into the ends that meet and connect them with a spline.

bad ascii art to follow: scarf (the angle would be much sharper (more acute)) ____________ ___________ | / / | | / / | | / / | |________ / / _____________|

[Danny Boy]

Over that length you *will* be supporting and attaching it on a good strong frame. If you can get he 10' length home intact, do so. If not, join two with either a long spline (my preference, but there are pros here much more knowledgeable) or biscuits. Once joined and glued it should hold when screwed to the frame well enough.

3/4"? The old school desk I'm sitting at right now is 1.5", and it's only 5' long. As I said, oak, but more 'solid', not ply veneer.

Dan.

[Greg O]

But would that be 36 or 54 degrees?? and which angle do I set on my Craftsman scarf joint cutter?? Greg

[KB8QLR]

Hi Chris, How about a tongue-and-groove? You would have to do the cutting with a router. I had to chuckle when thinking about doing it on the TS. Have fun ! Joe

[Ian Dodd]

Others have suggested scarf joints, splines and other solutions. Here's another thought, it's what I did when faced with a problem similar to yours. I needed to join two pieces of 3/4" ply to make a

12' long board. I made what was essentially a giant rabet by removing half the depth (3/8") by a 6" section of the end of each piece to create a 6" lap joint. With a limited selection of tools I did this by using a borrowed router with a 3/4" staight bit and making about 8 passes side by side (3/4" X 8 = 6"). That was for a bookshelf project and worked great.

For an accompanying desk, I had to do several end to end joints at various angles, not to make one long board, but to do a built-in into a 5 sided U-shaped space. For these I used biscuit joints. Each section was also supported by the underlying framework. This desk now carries two 19" CRT monitors, printer, fax machine, answering machine and an ever-deepening pile of papers with no problem.

My $0.02 worth,

Ian

[jo4hn]

[snip]

Got me giggling on that one. LOL. mahalo, jo4hn

[jo4hn]

You might think about tongue and groove or a glue joint (need router or shaper). A cleat glued and screwed to the underside will improve strength. mahalo, jo4hn p.s. A ten foot desk? You must be awfully busy. :-)

[J T]

Sun, Apr 18, 2004, 4:07pm (EDT-3) cf [e-mail] (Chris) claims: I'm a real newbie desktop out of oak plywood (probably 3/4"). ten foot piece of plywood

OK. I've read this several time, and the responses, and am still puzzled.

Do you want to make a desk, ten foot wide? Which would be one Hell of a large desk. Or, do you want to make a table, ten foot wide?

JOAT The Good are Innocent so they invented Justice. The Evil are Guilty so they invented Mercy.

- Unknown

[J. Clarke]

Marine plywood used to come 12' long although I can't find an online source without more looking than I want to do right now (try M.L. Condon, they don't have an ecommerce site but if it's used for boatbuilding odds are they have it).

describes a couple of accepted methods of making structural joints for boatbuilding.

lists attachments for several brands of planer (hand-held planer, not fixed mount) for cutting scarfs acceptable for aircraft use.

[Fred the Red Shirt]

4 x 10 and 4 x 12 are standard sizes for matine plywoods.

[Chris]

I'm making it 10' long and a little over 2' wide. Thanks for the responses by the way...

[Chris]

Actually, it looks like a 4'x10' piece is a regular stock item. I think the opening is about 1/8" bigger than 10' so I may need some sort of shim to fill up the space. I wonder if there is a decorative way to fill the space on all three sides with some sort of a molding.