Bending doublers

by Raymond Paul

Jun 28, 2012

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.

  • Tim Smart

    Raymond,

    I do not know what you have for a brake so I can only offer my experience. I first bent some material over a piece of angle bolted to one of my benches, the results were similar to what you describe, and so were my remedies, wider width material etc., all with the same results. I also read somewhere to bend over the desired angle and then open up or qualify the bend by opening up the angle by tapping the angle over a piece of PVC pipe. Didn't work. Next I built a version of "Dave's Sheet Metal Brake". When building the brake I was very carefull that the edge of the anchor angle was as parralel as I could make it to the bending angle. I attached the brake to my other bench which is VERY flat. After trying samples I can and have bent .040" material ninety degrees and 8' long. When I checked my original bench I found it to NOT be very flat at all. I think this was my original problem. Hope this helps, best of luck.

    Jun 28, 2012

  • Tim Smart

    Raymond,

    I forgot to say that my long bends are very straight with no curl or bananna effect at all. Again, good luck, hope this helps.

    Jun 28, 2012

  • Ron D Leclerc

    Hey Raymond...

     

    I don't know what you have for a brake... but mine is pretty crude, but works excellent.  Built it out of wood... see my brake photos!

    http://www.zenith.aero/photo/albums/5-bending-brake

     

    Bends stuff straight as an arrow... bends 0.040 stuff no problem.  Brake is 5' and took 3 hours and about $50 to build.  Biggest cost was 6 - 3" Stanley door hinges.   Wood is great for soft aluminum... but you have to build the brake just right!

    Ron

     

     

    Jun 28, 2012

  • Raymond Paul

    Thanks Ron and Tim for your advise I will work on it. I made up my bending break using the Zenith bending break plans only made it 6 inches longer so as to get the rubber spar in it. I will double check the flatness as well of the angle plates I used.

    Jun 30, 2012

  • Raymond Paul

    Hi Tim do you have a link for me to view Daves sheet metal brake

    Jun 30, 2012

  • Tim Smart

    Morning Raymond, (sorry your evening),

    I am on a little I-pad type thing and don't know how to attach a link so... Google "Daves cheap sheet metal brake" and one of the first links up just now is for his plans at ch601.org. It is a good set with great pics and explanations. As a side note, when I built my brake I ruined the 2" aluminum hinge so I went to a 2" stainless steel hinge and stainless steel pop rivets at a pitch of about 30 mm. Hope this helps, let me know if you need anthing else

    Jun 30, 2012

  • Raymond Paul

    Thanks Tim, will check this out right now. Oh by the way it is 11 am now here in Zimbabwe. Enjoy the rest of your weekend there.

    Jun 30, 2012

  • Tim Smart

    Raymond,

    The coffee is kicking finally, one thing I just remembered. When bending longer lengths of material when I have to remove the center clamping bolts for the material to pass through even the 1/4" x 3" angle iron will give in the center. I solve this by putting a block and jack on top of the clamping plate and jacking against the overhead keeping pressure on the middle. IF NOT AND THE PLATE GIVES THE ANGLE WILL HAVE A BOW. I not familiar with your brake but could this be happening in yours?

    Jun 30, 2012

  • Raymond Paul

    Ok I need to check my brake as it is very similar to Daves brake but with yours and Rons pointers I need to follow up. Let me see if I can attach a photo of my brake, forgive me if you dont get the photo not good at these computer tasks

    Jun 30, 2012

  • Raymond Paul

    Jun 30, 2012

  • Raymond Paul

    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.

    Jun 30, 2012

  • Tim Smart

    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.

    Jun 30, 2012

  • Raymond Paul

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

    Jun 30, 2012

  • Ron D Leclerc

    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

    Jun 30, 2012

  • Raymond Paul

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

    Jul 1, 2012

  • Ron D Leclerc

    Raymond

     

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

    Ron

    Jul 1, 2012

  • Ron D Leclerc

    Hey Raymond

     

    Here are some jpg files

    Ron

     

    Jul 1, 2012