QUESTION: Has anyone used biscuit joinery on 3/4" plyw

[mikeschn]

This summer I played with biscuit joints in plywood. Below is a picture of what I used biscuit joints on... The walls are plenty strong as long as you are careful moving them. I would not apply any real pressure on the joints until I have the 5.2mm luan glued on both sides of that joint.



Mike...

[cracker39]

That's the plan Stan...oops, I mean Chris...

[Chris C]

Good, Dale, that's what I was talkin' about! Mike knows his "stuff"!

[cracker39]

This summer I played with biscuit joints in plywood. Below is a picture of what I used biscuit joints on... The walls are plenty strong as long as you are careful moving them. I would not apply any real pressure on the joints until I have the 5.2mm luan glued on both sides of that joint.

Mike...

Now that I have the biscuit joiner, I'll probably use it on my framing pieces (spruce) as I glue and screw them to the outside skin (1/4" or 5.2mm Luan). As it is, I'll have 2 full length vertical framing pieces for backing the joints of the three plywood skin pieces and one full length horizontal framing piece on each side (except for door cutout), which I'll lap joint with the verticals. The other pieces I can biscuit join where needed. That should make for a pretty stable side wall.

[mikeschn]

which I'll lap joint with the verticals. The other pieces I can biscuit join where needed. That should make for a pretty stable side wall.

Sounds plenty strong to me...

My weekender walls were only butt glued, and it was surprisingly strong...



Mike...

[cracker39]

I had planned to only butt glue my framing pieces too. But, since I have the biscuit joiner, I have to play with it some don't I?

[randy chesnutt]

i used a bunch of biscuits in building my tear. from joining plwood to cabinets. on the 3/4" plwood i double roll of biscuits. i have used them for years. they do help line up the peaces. on the walls i have my framming behind it and it works out great and the framming was put together with double row biscuits only. but evey craftmen has his on way.

[Chris C]

Dale,

I plan on building my framing out of one piece of 3/4 plywood and cutting all the material away that doesn't look like framework. That would be a whole lot easier than fastening all those joints. That's how Mike has done it and it sure makes sense to me. But I am going to have to join two sheets together because I need more than 48" in height.

[cracker39]

Framing with plywood may be less work for yours, but I don't think it would be less for mine. I also have more attach points for the bed framing and bed support, the galley cabinet, door and three windows. And, I'd have to buy 6 sheets of 3/4" plywood to do that. as the cabin will be close to 12' long and just over 6' high. The spruce 1x8s I will buy and rip for framing and spars are much cheaper and not all that much more cutting than cutting out the openings in the plywood. It's all in what works for the individual and his/her trailer design. When you get right down to it, there are very few wrong ways to do it.

[mikeschn]

Wrong ways to do it...? Click on the hall of fame, and look for Sams toybox!!!

Mike...

P.S. Of course, by now, Sam's probably got it all fixed up... I'll have to go look and see...

[randy chesnutt]

you know i found a bunch of 1"x6" different length shipping crate. i found a company that received materail in crates. they were glad to get them out of there. free lumber. you might look around and you may find some that's what i build my wall frame out and many more parts of the teardrop. that save me a few bucks. i still have some left over. i just fiqured out i used 200 biscuits on the teardrop.

[doug hodder]

I would recommend using your biscuit jointer like a router....just cut a slot full length of the joint on the plywood, both sides..making sure both outsides are up or down, just so that if it isn't exactly centered the joint will still work...draw it full length of the joint....rip up a spline of hardwood to fit into the joint and glue it up....ideally a 3 wing cutter in a router is made to do the job....but it could be done with the biscuit joiner...just make sure to check rotation of your cutter so that you are pulling against the rotation not with it....start with either #10 or less and work up to #20...I haven't done it, but I'm sure it can be done...just get a good grip on the tool...and you might want to think about clamping the tool in a full "in" position or you'll be fighting it....It'll work the same as a router and a splined joint is going to be stronger than a bunch of biscuits...especially over 3+ feet....I know the tool isn't made to be used like this...but it's an option if you feel confident in the use of the tool....just my thoughts....Doug

[halfdome, Danny]

No matter what you use biscuitts, lap joint or a spline I would recommend using pinch dogs to pull the joints together while the glue dries. Pinch Dogs are a Cabinetmakers friend. They are made out of steel and the more you hammer them in the tighter your joint is. As a Cabinetmaker I would use a 1/4" spline and scarf a piece of plywood the same thickness as your lumber framing is over the joint. If you were to use lumber for a scarf it could split but a good plywood core wont split. I'll use Baltic Birch for all my plywood as it is very strong. That's just my 2 cents worth.

[Chris C]

I would have to agree with you all the way on this one, Halfdome. Splines in Baltic Birch are great. Baltic Birch also gives a better bite for screws than regular plywoods. I plan to use it exclusively in my tear. Only problem is it comes in 5' x 5' sheets, so I'll have to spline them all together before I start cutting out my framing. But it'll be a stronger wall for the effort, don't you think?

[halfdome, Danny]

No matter what you use, lap joint, biscuitts, spline or scarff joint I would use pinch dogs to pull the joints together. Pinch Dogs are a Cabinetmakers friend. They are a piece of steel that pulls the joint together when you hammer them over the joint. As a Cabinetmaker I wouldn't trust a biscuitt for this application but would use a 1/4" plywood spline and a scarff joint of a good grade of plywood the same thickness as your lumber framing. A lumber scarff could split under stress but a good plywood core won't split. I'll use Baltic Birch for all my plywood as it has great strength. That's just my 2 cents worth. Danny[color=blue]