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  • September 20, 2019, 06:49:13 AM

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Author Topic: Warp help  (Read 285 times)

Offline John Watson

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Warp help
« on: September 10, 2019, 08:06:03 PM »
Warped profile fuselage Clamped it down to a flat surface for a few days. Any suggestions?

Offline Steve Helmick

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Re: Warp help
« Reply #1 on: September 10, 2019, 08:21:35 PM »
Is this a bare balsa profile fuselage blank or is the airplane already built and finished?   ??? Steve
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Offline Tim Wescott

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Re: Warp help
« Reply #2 on: September 10, 2019, 09:59:19 PM »
Painted or bare, just clamping it flat won't help.  You need heat, moisture or both, and you need to bend it past where it is now.  What works best for me, as a first cut, is to bend it just as bad the other way.

Take a picture, show us what you've got.
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Offline John Watson

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Re: Warp help
« Reply #3 on: September 11, 2019, 09:30:46 AM »
A bare blank that I was sanding and didn't notice the warp at first. I will try bending the opposite way and appling heat.....

Offline Tim Wescott

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Re: Warp help
« Reply #4 on: September 11, 2019, 03:29:32 PM »
A bare blank that I was sanding and didn't notice the warp at first. I will try bending the opposite way and appling heat.....

As best as I can tell, with bending balsa wood it's mostly the elevated temperature that does the job, but some moisture helps a bit, and and does a lot to conduct heat into the interior of the wood.  So if you're bending it dry, take a good long time to get it warmed up.  If I'm un-warping a profile fuselage I may spend five minutes or more playing a heat gun over the back half of the fuselage, trying to warm the wood without blistering the paint.

Personally, if it's in the bare wood stage I think I'd at least spritz it with water, to generate steam that'll conduct heat to the interior and to (hopefully) loosen up the top layer of fibers a bit.

One of these days I'm going to make me a full-on steam bending fixture.  Eventually.  Before I die.  Maybe.  Or I'll just direct in my will that I be buried in a steam-bent coffin.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Joe Ed Pederson

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Re: Warp help
« Reply #5 on: September 11, 2019, 05:49:24 PM »
I was able to straighten a warped fuselage blank by following advice given on the forum. 

The advice was to get a plastic storage container large enough so you can put  the fuselage blank in it lying flat.    Wrap the fuselage blank in an old towel.    Boil water.    Pour the boiling water onto the towel being careful not to burn yourself.   Soak both sides.     Give it a few minutes.   Unwrap the fuselage blank and put it on a appropriate flat surface with the end of the fuselage propped up to bend it in the opposite direction of the warp for a while, then at some point (my memory is a bit hazy here regarding how long) take out the material that propped it up and let it dry while held down flat.

Obviously, there's a lot of guess work in the "how long" and "how far" quantities.

Of course, another option is to chuck the warped fuselage and buy a straight piece of wood and cut out a new blank.

Joe Ed Pederson
Cuba, MO

Offline Motorman

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Re: Warp help
« Reply #6 on: September 11, 2019, 08:46:25 PM »
Make cheek cowls out of it.
There will be a sunny day and we will fly our airplanes.

Offline John Watson

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Re: Warp help
« Reply #7 on: September 12, 2019, 12:32:04 PM »
Got the warp out. I put a wedge under the warp and clamped both ends down overnight and most of the next day. Straight as an arrow. Didn't apply any heat or moisture. Hopefully it will stay straight......

Offline Tim Wescott

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Re: Warp help
« Reply #8 on: September 12, 2019, 01:03:32 PM »
If you have the time let it sit flat on the bench for a while and see if it pretzles.

Chances are it was straight when it was cut, and it "wants" to be straight, but it got warped by being held in a bend in the box.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.


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