Best way to bend luan without cracking it????

[Eric Adams]

I have some 1/8" luam and need to bend it on a radius (think the front upper corner on a Benroy) and my thought is:

1) Wet it with hot water (how much??)
2) apply heat from a salamander heater
3) liquid nail an screw to the TD
4) Let dry and then epoxy and glass it...


Right??


Also-

If I glass the top do I have to use cloth on the whole top or just on bends and structural areas??

[Arne]

All of the above...... it bends easier with the grain across the tear.

Attach on one edge, put some straps/ropes and boards to keep it from getting dinged up..... wet it, put on some pressure... go have a few beers....

Give it some time to accept the new shape without breaking... 1/8" should not be that hard.

Except, I would not use heat (dry it out, bad)...... I would shape it first, then remove and put on glue. Kind of time consuming, but the end result might be better...

[Eric Adams]

All of the above...... it bends easier with the grain across the tear.

Attach on one edge, put some straps/ropes and boards to keep it from getting dinged up..... wet it, put on some pressure... go have a few beers....

Give it some time to accept the new shape without breaking... 1/8" should not be that hard.

Except, I would not use heat (dry it out, bad)...... I would shape it first, then remove and put on glue. Kind of time consuming, but the end result might be better...

"Attach on one end" Just do one side at a time?

The garage will be cold so I will probably warm up the whole garage with the salamander, just not the wood directly right?

Should I start the end of the wood at a curve or the front flat part of the TD?

[Arne]

If I was doing the front, I would start at the bottom and go up... it should be kind of obvious, you start at an edge.... for the front, it would be the bottom edge..

Maybe I'm just confused.... anyway, I put a cleat sticking out under the bottom on each side (held in place with a floor jack and a 2x4... the ply sits on these and that aligns it across the tear.... put a board across the ply to for support, screw through the board, through the ply into the tear. Now the bottom edge is lined up and go from there.....

Start to bend and see how far it will go... I'd put a board across the top to support and strap it in shape.... start wetting it, leave some stress on it, and leave.... come back in a while and see if you can bend it some more and tighten straps..... keep going till it is seated where you want it......

After it dries and is stable, I'd remove it, apply glue, and reinstall and screw in place.......

[McTeardrops]

I've had my 1/8" birch ply and 3/16" masonite wrapped in bungee cords for a couple weeks, and now have just about the 20" radius for the front curves. The 1/4" birch ply is racked in a pair of 6 foot pipe clamps and is just about ready to be a hatch skin. Inside of the hatch will be 1/8" FRP, it was ready right off the shelf

[SteveH]

A trick we use building model airplanes to warp wood either into or out of shape is to use amonia. Mix about 50% amonia with water and wet the wood with the solution, bend the wood into the position you want it, and let it dry. The wood will assume the new shape.

[Eric Adams]

A trick we use building model airplanes to warp wood either into or out of shape is to use amonia. Mix about 50% amonia with water and wet the wood with the solution, bend the wood into the position you want it, and let it dry. The wood will assume the new shape.

Might seem like a dumb question but...sudsy ammonia or regular???

[SteveH]

Regular amonia you buy at the grocery store for cleaning.

[Guy]

When yopu bend plyood or any other wood you use steam to prepare the surface and keep it from checking or cracking. This can be accomplised with any steam source, ie pot of water, iron, your spouses steamer to take creases out, or one of those steam cleaners which are sold all over.

[fornesto]

I might have a unique situation, but in my garage, I have rafters that cross width-wise over the floor. I stood the 1/8" plywood up, starting at the front nose, with the plywood on the door-side of the rafter. I slowly pushed the trailer forward and it caught on the rafter. Pushing it slowly, it bent along the front curve of the trailer very evenly. As I moved along, I just pushed the trailer forward a bit. That worked for the front curve very well. I went against the grain and had no problem. I also used a lot of screws though.

[doug hodder]

I've steam bent small sticks of material, but it might be tough on a sheet of plywood. For me, I boil about 5 gallons of water, lay a blanket or 2 on the top of the plywood and pour the water on. I let it sit about 45 min. pour another load of boiling water on it and then try to bend it. I've bent up to 3/8" plywood, using this technique on compound bends with good results, at least for boat hull curves. I'm sure others have different methods, but this is what worked for me. You may also want to back up the plywood with a piece of cheap 1/8 masonite on the outside of the curve to equalize the curve and pressures. If you are using polyurethane glue the dampness is going to be no problem as they rely on moisture for their curing. Yellow glue may be an issue however. Doug Hodder

[asianflava]

I have 1/8in birch and luan. They both bend around the trailer curves with any problems. I haven't done anything to them and they seem fine. I may wet it when I do the tight radius on the aft end.

[len19070]

I've never had any problems bending any 1/8" material be it Birch or laun (never used masonite) on a 4' wide trailer the 8" direction...BUT when building a 5' wide unit and bending the 4' direction, and having to put a splice in the middle I have had to do a little thinking. First I plan the seam in an area that has a gentle curve. Thats the most important thing. I cut the plywood to the width, warp it 25% narrower ie a 4' should be warped to 3', I used a jig I took a full piece of plywood and screwed 2 2X4s 3' appart and bent the ply and set the edges inbetween the 2X4s, I laid an old blanket over the arched plywood dumped some hot water over it and let it sit over night. The next day it looked like Rocking horse legs.

Happy Trails

Len

[purplepickup]

Doug and Len...After you do the blanket and hot water method, do you go ahead and glue the panel while it's still wet or damp? Doug, I noticed you said urethane glues use moisture to cure. Could you suggest the best glue to use in this situation? I'm not a woodworker but I'm trying to learn.

[Shrug53]

hey that clothing steamer sounds like a good idea. I just saw an ad for one of those on TV.