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Old Jan 31, 2013, 07:56 AM
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Forest, Va
Joined Nov 2009
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Twisted Balsa

I purchased about $160 worth of balsa sheets 3 inch wide 48 inches long varing thickenss 1/16 thru 1/4. I have had it for 3 - 4 months stacked on a flat shelf in a fairly climate controled basement. Much of the 1/16 stuff once removed from the stack would start twisting. I would keep the heavier stuff on top. After cutting it into 14 inch sheets (size for the laser), it would seem to twist worse. Now, just about all of it is twisting (15 - 20 sheets) and the 3/32 stuff is starting to twist. I'm confused???? I have other stock that I have had for 20 years stored in the same fashion and location that is still straight as an arrow. Any ideas on what is going wrong and how I can fix it? I'm guessing the moisture content was too high when it was shipped and now it is drying out! Not interested in bashing any companies, just wondering if there is a way to fix it. Also, this may be an example of lowest price not always the best.................

John
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Old Jan 31, 2013, 08:17 AM
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epoxyearl's Avatar
United States, MD, Elkton
Joined Oct 2011
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I buy #2 and#3 balsa from a well known Company, on purpose.

I usually buy a couple of hundred dollars worth at a time,intended for sheeting LE's and shear webbing.

I store the stacks under a 1/2" thick aluminum plate.-That doesn't work either.I have soaked the sheets in the bathtub,weighted them down for a month,and when I remove the weight- more 'propellors'! Hot water, cold water, ammonia,
it makes no difference..

It's not a 'problem' to me, but I can't suggest anything to help you. I have tried twisting them the exact amount in the opposite direction,with no success.

It does lie flat when glued though.
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Old Feb 02, 2013, 11:30 AM
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Joined Apr 2012
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It was probably sawn wrong. Most any straight piece of balsa will warp, bow or cup when cut.

Here's how I handle it. Say I have a 3" wide sheet and need 2 1/2". I don't cut a 1/2" piece off. I cut maybe a 1/8" off one side and see what happens after it sits a few minutes. If it bows I know that it has a lot of tension or compression on one side or the other. I'll then cut about a 1/8" off of the convex side and wait a while. I usually go back and forth a few times. Usually I can get a straight piece, but not always. After doing this a few times, you will know exactly where to trim some off. Generally if you get a straight piece, it will stay that way.

Good luck.
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Old Feb 05, 2013, 02:23 PM
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Leroy Gardner's Avatar
Coeur d' alene, Id.
Joined Jan 2010
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Quote:
Originally Posted by gwilliams20 View Post
It was probably sawn wrong. Most any straight piece of balsa will warp, bow or cup when cut.

Here's how I handle it. Say I have a 3" wide sheet and need 2 1/2". I don't cut a 1/2" piece off. I cut maybe a 1/8" off one side and see what happens after it sits a few minutes. If it bows I know that it has a lot of tension or compression on one side or the other. I'll then cut about a 1/8" off of the convex side and wait a while. I usually go back and forth a few times. Usually I can get a straight piece, but not always. After doing this a few times, you will know exactly where to trim some off. Generally if you get a straight piece, it will stay that way.

Good luck.
Your right, sawn wrong from small trees and it will all go bad. Grain in balsa is hard to see and when the moisture goes out it goes nuts from the tension. Most high grade wood is 1/4 sawn and will stay flat and only minor dressing on the edge is needed, All wood is graded, A being the best and the hardness is also graded. If you order from a reputable dealer and specify the grade you want your more likely to get it, off the cuff your liable to get anything.

Leroy
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