Hi guys

I have a question and was wondering if you can help me out. I'm finishing up my sheet metal brake to build the CH 701. I was reading about the different bend radius for the different thickness of material. 

Do people just use one size radius for the bends on both .025 & .032 and even the .016? The brake i'm building is the "Dave's sheet metal brake" that seems to be popular. I clamped the edge of the angle down and put Dye-Chem marking ink on the edge of the steel. I then took a file and cleaned it up to near perfect. What radius should I put on it?

According to the Zenith builders manual I should be using a different radius for different thickness. The brake is 8' long, should I have 3 different pieces of angle iron each with a different radius?



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I believe that you bend all the same radius until you get up to the  .063 and up.  That what I do. My brake is build with a 3.2mm radius

Most of the thicker parts are smaller brackets and such.  I made a hardwood block with the proper radius on the edge.  I sandwich the part blank between two blocks and line up the edge of the block with the bend line.  Once clamped firmly in the vice, I simply bend the part to the proper angle using a mallet.  I've made the elevator control horns and center hinge brackets like this and they have turned out well.

The minimum bend radius for different thickness of aluminum can be found in AC43-13-1B and 2B. Copies can be downloaded here:


and here:


Basically, the thicker the aluminum, the larger the radius you need.

Thanks for the help guys!


I used the 3.2mm radius for all up to and including .040" and for .063" bent up two thicknesses of .040" under the brake which worked great.. Using Dave's brake have made all the parts for a 601XL and most parts for a 701SP.  The 7F5-3SP did beat me as it was difficult to stop the part slipping under the brake with the two thicknesses of .040" but other .063" were good.


Good luck and if you take your time positioning the material under the brake you will have accurate parts.




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