WILDCRASHWILLY

I wanted to mix a solution of amonia and water to help where I need to bend some 3/32 balsa. Can any one tell me what the best mixture is %water vs %amonia.

Thanks in advance for any information you can share.

Bill

Live Wire

Why not Windex window cleaner!
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Campy

My Feedback: (1)

I just SOAK mine in some warm water for about 20 minutes (weighted down so it is all under water). Bends easily. Bend it and fasten it in position with some cloth straps and let dry (normally overnight ). When dry, lightly sand to remove the "fuzzies" and fit and glue in place.

HINT: If 3/32" is too thick for the radius bend you want, bend three 1/32" pieces and when dry, laminate/glue them together to make your 3/32" piece.

CafeenMan

I quit using ammonia because it does strange things to wood. I think it actually damages the wood cells or fibers or something. Soaking in hot water works great.

saramos

What types of effects have you noticed? Is there a loss of strength, sandability, change in weight? I've seen lots of posts about using ammonia, and have used it myself. However, I find the info you provide to be very good and would like to avoid trouble on my future builds.

Thanks,
Scott

CafeenMan

Scott - I can't really describe it. It doesn't give me problems exactly, but it seems to make the wood turn "strange." I know that's not helpful, but like I said, I don't really know how to explain it.

One thing that does give me problems is when I try to glue the wood while it's wet. When using water, I can glue with Carpenter's glue while the wood is wet. With ammonia, the glue turns milky white and I don't trust the bond. I don't think mixing ammonia with carpenter's glue is a good idea anyway.

I've simply stopped using ammonia altogether. Wood bends just as well using really hot water and giving it some time to soak. Half the time, I just run hot water over the wood for a minute and it's ready to go (more gentle curves that are too much for dry wood).

CafeenMan

I'm uploading few pics of what I'm working on right now. Give me a minute to download them from camera to computer and resize them.

CafeenMan

The sheet of wood shown here is 1/16" balsa. I ran it under hot water for a minute or two and then bent it into place. It's just being fit right now - no glue is applied. In fact, the front former is not what it gets glued to. There's another former that is identical to it that is glued to the back of the one shown.

The sheet bent into shape easily, but isn't quite right in the photos. There will be a stringer going from former to former for the sheet to glue to. Once the sheet is glued in place, it will be sanded flush with the stringer and another piece will cap the joint so that it's clean and strong.

Covering this thing is going to be a nightmare. I may just use crayons.

Oh yeah, the other two photos are not related to sheeting but I thought I'd show them just the same. All 5 servos are mounted in the center of the plane keeping them close to the CG. I expect this model to move easily about all its axis. About 500 inches of wing (biplane) and 40 ounces or less all up weight.

If it ground loops, the wings will be totalled. They're very delicate.

saramos

Thanks for the reply and photos Cafeenman.

Scott

CafeenMan

A few steps further along. I did the exact same thing with both pieces and let each dry in place. They are now "molded" to shape. I've just glued the first one on. When it's dry, I'll trim it and glue on the second piece.

If I had tried to bend this piece while it was dry it almost certainly would have cracked.

Every time I've had problems bending balsa it was because I was impatient and didn't work slowly enough when bending it or I didn't let it soak long enough to be pliable or I used the wrong grain of balsa. That last one isn't often true. Normally it's me trying to make the wood take shape too fast.

Anyway, hopefully this helps WILDCRASHWILLY with whatever it is that he's working on. Balsa is amazingly pliable stuff.

Last thing... use water base glue whenever gluing a piece on that needs to be bent. If you find out that the balsa simply won't take shape, then remove it immediately and use a wet paper towel to remove the glue.

Better to start over than to force a bad situation and have even more problems fixing it later.

WILDCRASHWILLY

Thanks Cafeen and the rest of you as well. Great information, I bent a prior model and had some minor cracks but the plane flew well for almost a year. After tharoughly crashing it last fall due to pilot error, I'm building another Hots and thought I would take a little more care at the Balsa bending stage.

Again thanks everybody for the tips, Merry Christmas.

Bill

pt19 flyer

My Feedback: (1)

hi

what I haveused for many years is put ammonia(household) in a spray bottle and spray the outside of the balsa, wetting good and apply to surface and hold down with rubber band, pins,etc. also I recently read, I think in rc modeler, to brush on thinned elmers glue to both sides, after cutting to fit, then apply to surface, have'nt tried this myself but sounds workable.

happy flying
pt19 flyer

Mike James

Interesting...

I've used plain water, dabbed onto balsa sheets or sticks, with a damp washcloth, for many years, and have never seen the need to use ammonia or any other exotic mixtures. If you just wet the wood, bend it slowly, wait a minute, etc., you can, as the man said "sheet a golfball". I think that like many other modeling tasks, time is the key. If you get in a hurry and bend the wood too fast (wet or not) you'll crack it.

I made some balsa wheel well liners at http://homepage.mac.com/mikejames/rc...solutions.html for example. (scroll down to about the middle of the page.)

Nice work, and photos... as always, Paul.

CafeenMan

Thanks Mike. That's a good way to make wheel well liners. And no grain to fill either.

Saramos - I thought about the ammonia thing a little more and here's what I don't like about it. First, it makes the wood kind of mushy. Water softens it and makes it pliable, but ammonia makes it too much so. What I've noticed is that the wood will be more likely to sag between supporting members such as ribs or formers when ammonia is used. Doesn't always happen.

Also, the wood seems harder when it dries. In any case, the finished result has never caused me any problems with ammonia or water but I like plain water best.

JL1

My Feedback: (93)

Sagging or other distortions can be caused by glueing the wood in place before it is dry. As the wood shrinks it creates stresses in the sheeted area.
I hold wet sheeting in place with Ace Bandages until it is dry and then I glue it.

rctrax

50-50 mixture is what I use. I bend 1/16th around the leading edge. The trick is to hold it with an ace bandage until it is dry and then glue.