hello all, i crashed my hangar 9 p-51 mustang a lil... im tryin to rebuild the top rounded section right behind the canopy. i keep trying to bend the balsa sheet around that hump but it keeps breaking. its the same thickness as the balsa thats was on there, and imm having the grain of the balsa go with the length of the plane. can i wet the balsa? or humidify it in the bathroom? or is there some other trick to bending the balsa? any help greatly appreciated!!!! thanks in advance!!!
-kevin

I believe if you wet it, then once its glued on dry it thoroughly with an air dryer it will be fine.

lay a piece of wet cloth on the outside of the curve. If it is really a tight bend, soak the balsa in a pan of watter with a couple ounces of hosehold amonia. Soak it for a half hour or so then tape it down into place and let it dry out. It will take the curvea and hold it. You can then glue it down with your choice of glue. You will have to much water on it otherwise for most adheasives.

Also, selection of balsa is in order. If you have some with a noticable color change, it is going to give you trouble. Consistant color ususally indicate a consistan density. With good balsa, you usually don't need the amonia, just some wet rags on the outside of the curve for a few minutes is enough.

Don

My LHS told me to use denatured alcohol and it works great and evaporates very quickly.

Gary

I've always used 50% water and 50% alcohol (91% at walmart)...

LD

I use Parson's Sudsy Household Ammonia to wipe the balsa well when bending sheets. Watch for VERY fast CA bonds with the added moisture and base from the ammonia. Set it in place with T pins and then tack it with CA.

i use the alcohol and normally use a spray can or something similar to the shape i am trying to make let it dry then glue it in place.

Warm water and amonia.

G'day Kev,
Use straight cloudy ammonia, just wipe it on, let it soak in, & pin in place, when dry, overnight, pull 1 pin at a time & put a drop of CA, in the pin holes, done.

another suggestion is if the wood is of a thick and hard quality , you would be better off using a thinner and softer wood and laminate. say if your trying to bend hard 1/8 inch try two laminates of 1/16 inch.

I have bent hundreds of sheets and have never found the need for anything but plain ol' warm tap water.

If you wet only the outside, that side will swell and start curving the sheet before you even try to bend it.

Same here as by Minn Flyer.

Built CL, FF, and RC models for over 60 years, including many of my own designs. Bending the RIGHT grade of balsa has never required anything more than some water on one side the outside of the curve. I have even rolled balsa into tubes, of course with limitations.
TIP: If you buy Midwest balsa, which is marketed for the craft trades, then it is of a rather strong grained wood, and is relatively difficult to bend, but excellent and expensive wood for framing larger RC models. Buying balsa from the suppliers such as Sig, etc and purchasing the lighter softer grains where molding is needed, bending is no problem.

freeair's suggestion is also, IMO, 100% right on. BTDT!

In some projects, don't overlook the often ignored 1/64" birch plywood. That stuff is great for MANY purposes including forming turtle decks, cowls etc., etc. Much stronger than 1/16-3/32 balsa and not overly heavy.

My only experience is with molding a small fuselage and several leading edges out of laminated 1/32 sheet. I used plain water with a little spritz of Simple Green. The sheets were limp in seconds. The problem is with getting the balsa sufficiently wet. Ammonia is not needed. Ammonia is used on other hardwoods to soften the subrin and lignin compounds largely absent in balsa.

A builder of twenty years experience told me to use vinegar. I keep a spray bottle filled on the bench and can make very tight bends with ease. It is much less toxic to handle and breathe than thinners and ammonia.

Neal