Please can somebody help me before I have to open an inventory for plane #3. I am struggling to bend the doublers on the horizontal stabilzer.When the doubler comes out the bending break it looks like a dam banana, whats the trick to bending a doubler and getting it to stay straight. I even tried bending it on the edge of a full sheet and cutting it off after bending, this was a disaster, came out like a twisted banana!!. Thankfully I will be needing plenty L's in the build so hoping to recycle some of these doublers when used in short lenghts.

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Comment by Raymond Paul on July 6, 2012 at 12:12am

Thanks Chris, for this very useful information. I am reworking the hinges on my brake and then will cross check it with your informantion . To ALL that have contibuted to helping me solve this issue, many many thanks ,till the next hurdle comes along which I am sure is not far away, hit a hurdle last nite. My zenith photo assemble guide for stabilzer skin section is corrupt!!!!!!!! after page 3 so need to get hold of zenith to get this info some how

Comment by Chris Aysen on July 5, 2012 at 2:35pm

Raymond - The banana affect is due to unequal downward pressure across the length of the material. The twist is due to having one portion of the work piece clamped and having linear movement (ever so slight) on the opposite side before full downward pressure can be applied. Keep these two rules in mind before bending. A slight banana affect can be taken out by using crimps like you use to take up material on a radius (nose ribs). Start in the middle of the bend and work your way outward. You should not have to go very far outward. It would not take very many crimps, they would not be very deep, and would not hurt structurally. Use a good straight edge and continually check the part for straightness as you apply the crimps. Just make sure the crimps are between rivets. Naturally you would like to avoid having to use the crimp method but it is workable.

Comment by Raymond Paul on July 1, 2012 at 11:57pm

Hi Ron, email is kiaoraflora@gmail.com

Comment by Ron D Leclerc on July 1, 2012 at 11:13am

Hey Raymond

 

Here are some jpg files

Ron

 

Comment by Ron D Leclerc on July 1, 2012 at 11:04am

Raymond

 

What is your email address? It's a PDF file!

Ron

Comment by Raymond Paul on July 1, 2012 at 12:38am

Morning Ron, thanks for your input here, yes please send me your drawing of your break as any help I can get is appreciated

Comment by Ron D Leclerc on June 30, 2012 at 12:02pm

Raymond

 

The 3" door hinges on my 5' brake are placed at 12" centers... and I also use an 8" C clamp which is a must at each hinge location to keep the part from moving.  One other thing that I also added was a strip of duct tape on both of the bending surfaces that way the aluminum is clamped securely between them.  I think that it is the duct tape that keeps the alunimum from moving between both of the bending surfaces!  I have built hat sections, "Z" angles, mulit angle channels etc. with no problems.  Wood is very forgiving... but it has to be the right wood, Clear douglas fir... it does not warp, holds its shape well and it hard as nails.  You can brake 1/8 bits very easy it you are not careful.  I  have a drawing if you want one!

 

This 5' brake will bend all of my 701 parts... except for the longer stab/elev, flaperon spars, longeron angles a total of 15 parts.  I will build an 8' brake when I need tit for the long stuff.   The 5' brake has worked so well that I will keep it... the 8' one is only for temporary use and will be dismantled after.

 

It took a bit of experimenting when I built the brake, tried to build it full length at first... but could not get the bends just right, played around for 2 years, so I started over and kept it simple and built a 6" one first and the 5' brake evolved from there.

Ron

Comment by Raymond Paul on June 30, 2012 at 5:05am

brake is exactly the lenght to bend the rudder spar think it is 4' 6 inch, will give it another try with your ponters

Comment by Tim Smart on June 30, 2012 at 4:53am
Raymond,

I don't know how long your brake is but I would try a test with a few "c" clamps in the middle of your brake if you can. That might eliminate any deflection problem and answer your question. I also try to leave at least a couple of inches of material on the open end to help eliminate the edge from digging into the brake angle as it is raised (some packing paper underneath also helps and saves some scratching on the aluminum). If you try this and it works to help save material waste bend a wider piece making a channel then cut down the middle after bending making 2 angles.
Comment by Raymond Paul on June 30, 2012 at 4:29am

Tim this is the brake I used to bend the rudder spar and the shorter spar for horizontal stabilzer and they came out perfect. I bent 1 doubler and it was perfect, thought this was all to easy, for some strange reason bending the rest of the doublers just seems not possible,I have a bunch of banana doublers to recycle into shorter L's for the build. Am building a 701 by  the way.

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