Bending Plywood

[Gerdo]

I have 5.4mm (3/16) birch plywood for my interior and I need to bend it around the front curve (20"radius). Are there any tricks that will help it more flexible? would getting it wet help?

[Ron Dickey]

I have not gotten this far but have been reading for years.

look at this his is something like yours

http://home.comcast.net/~bdosborn/tear/teardrop.html

look at his roof line. the bars inforce it and you glue to each with very strong glue. his bars he over killed with right angles most just glue and screw.

research it more go to seach above and enter roof or arch or both and see what you get.

you might look through here
http://q.webring.com/hub?ring=teardropper

good start

[Ben W]

I don't think you would want to soak the ply like you would a solid piece of wood. Soaking it for a few days would probably weaken the glue and warp the laminates.

[webbedouin]

You might try some long ratchet straps. Was bending 1/8 inch, just laid it in place, fastened the bottom edge, bent it over as much as i dared by hand and then used the straps to pull it tight over the curve. Worked really well.

[Endo]

Are there any tricks that will help it more flexible?

Kerf cuts. I made 72 kerf cuts about half the thickness of the plywood, it made it very easy to bend.





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[TomS]

I cheated. I used flexible plywood purchased from from these guys.

[Woody]

I got the board wet (both sides) with hot water and placed towels wet with very hot water on the boards prior to install. It bent fine. use supports props to hold in place during install. Seemed to work fine, no problems

[WoodSmith]

I've not made a tear drop (yet) but made a cradel boat which needed bent 1/4" ply. I used my wallpaper steamer and steamed the ply. It made a huge difference. Before the steam, I was using all my strength to get the ply to fit into the clamps I was using to prebend, and I could hear cracking. After the steam, I could easily get another probably 8 inches by hand. This was on a 4 foot long piece.

[Marck]

Endo,
How far apart are your kerfs??? From the pics, they look to be about an inch apart...is that right??

[Gerdo]

Well I cut and then hosed the ply down with water. I kept hosing it down for about an hour. I live in Denver so things dry quick so I was not too worried about the water. It still took alot of pushing and shoving to get the plywood into the curve. This is the inside so I could not use straps.

[Endo]

Endo,
How far apart are your kerfs??? From the pics, they look to be about an inch apart...is that right??

Marck

The kerf cuts are 1/2 inch apart. It took alot of time but it made bending very easy!

Endo

[ellisdee9091]

Gerdo
I would not recommend kerfing the plywood...from my personal experience kerfing just gives it a place to break...do not wet it, it will delam
I bend the interior ply on my trailers around a 20" radius with no problem.
I am also in littleton, actually a little south near santa fe dr. and titan road.
give me a call and we can meet at my shop and I can give you a little tech advise.
ellisdee
(steve)
303-791-2820
cell 303-503-1957

[doug hodder]

I used 1/8 material, but my grain also runs
lengthwise with the cabin..I went with 1/8 as it will
bend easier and since I was going against the grain I
needed all the help I could get. I used screws with
a backer block until the epoxy cured, then pulled them
out and decorated the spot with a stainless screw
with a finishing washer..I didn't use any kerfs, or water
to get it to bend....just muscled it in place and shot screws...
.Doug Hodder

[Marck]

Problem I have is I can't find anywhere locally to get 1/8th in ply
Best I could find when building the six-pack was 1/4

[Endo]

I would not recommend kerfing the plywood...from my personal experience kerfing just gives it a place to break

The kerf cuts make it so flexible if your not careful it will break. You need at least two people while installing the kerfed plywood.
Once it is glued to the roof spars and the roof insulation is glued to the back of the plywood it is as strong as ever.
Adding the exterior skin of plywood stiffens the whole "laminated" ceiling even more.

Endo