My design attempt

[R Keller]

RC: I did a 5" radius with 5/32" Finland Birch plywood on the front box of my Road Toad (see below). Not really a huge problem. Didn't soak it or anything. I did use a lot of screws. The grain is parallel to the curve.

The front curve of the Road Toad main body is a 10" radius. That was no problem at all. In the following photo you can see one separate piece on the front curve that I had to use because I was running out of wood. For that one the grain was running the wrong direction, so it was a lot tougher to bend and was closer to splitting, but it still worked.



Most likely the folks that are saying you can't do that 10.5" radius are talking about standard big box hardware store 1/8" plywood which is two paper-thin veneers sandwiching a thick middle layer. That stuff will split pretty easily. Same for paneling. Use a "proper" thin plywood that has more or less equal thickness veneers like Baltic Birch or Finland Birch and you should have no problems as long as the grain is running in the right direction.

Hope this helps!

Rik

[Steve Frederick]

If you use 1/8" ply, cut in half with the grain running wall to wall, I bet you can do it! You can get 2 by 4 cut sheets at Home Depot for a practice shot.

[Arne]

That is a good point. I used the sheets the long way to keep seams to a minimum (and use less ply). Going in the other direction might make a difference... I opted for a flat back for several reasons, one of which was a back wall for future galley. The other was for potential tail light mounting (that is still to be worked out).

It has come to my attention that once I put the vent on the roof, I shall no longer be able to get it into my garage to work on the tear.. so, that will be the last piece to be installed.

[R Keller]

Arne: it is a lot tougher going against the grain! My plywood was kind of screwy: the Finland Birch 4x8 sheets came with the grain running in the 4' direction. Since my trailer is 5' wide, I opted to use the 4' width with two 6" (4" on the interior) strips for the roof. The seam between these is actually a routed out channel that I run the wiring in. Another option would be to use Baltic Birch plywood. It is easier to find than Finland Birch and comes in 5x5' sheets, so you could orient the grain whichever way you wanted.

If you need to get crazy small radii, you could always use Italian bending birch plywood. That stuff bends like paper.

Rik

[Laredo]

if you have a lowe's in your area, look into the fiberglass roofing panels they sell. Some come in almost clear, some in a bluish clear, some in a grass green, some in a creamy white color. They're about 2 feet wide and up to 12' long. I've got to get some kind of carport-type thing going to park under (and work under).

[mikeschn]

Hey Rik,

I just called my speciality plywood store... it seems that baltic birch is normally available in 5x5 sheets. Is that what you got? In a 5x5 or a 4x8???

Mike...

[R Keller]

Mike:

Baltic Birch is typically available in 5x5' sheets. Finland Birch is typically available in 4x8' sheets. Baltic Birch uses interior-grade glues. Finland Birch uses exterior-grade glues.

Rik

[mikeschn]

Mike:

Baltic Birch is typically available in 5x5' sheets. Finland Birch is typically available in 4x8' sheets. Baltic Birch uses interior-grade glues. Finland Birch uses exterior-grade glues.

Rik

I called back, and my place doesn't have it, and can't get it. So I guess I am looking for a supplier...

Mike....

[Rick R]

You might also want to look for or try poplar bending plywood. I read about that somewhere (maybe here), for doing tight radius curves.

You might also want to try prebending it, by wrapping it with ropes, and using boards to keep it from bowing between the ropes, and leaving it to rest and take on the curve for a day or more, before trying to use it.