Replies to This Discussion

Permalink Reply by Glenn Andressen on March 18, 2009 at 5:37pm

Hi Grant,

I built a version of Dave Clay's brake, which is okay for everything 40 thou and under... and I did have to beef it up to get decent 40 thou bends. But for everything under that thickness it's fine.

As far as .093 and .125, anything that thickness I have so far bought from Zenair. Given scratch building is a long term project, I am prepared to place an order with them every few months or so.

Glenn.

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Permalink Reply by Grant Arthur on March 18, 2009 at 6:15pm

Thanks Glenn, that is the brake I was thinking of building. I was hoping to be able to bend larger material than that though. What mods did you make to beef it up? Also I noticed some of the larger pieces were labeled as extrusions and so I am not sure whether it has to be an extrusion, or whether it can be a bent piece without the squared off edges an extrusion provides. So I may not need a larger brake if this is the case.

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Permalink Reply by Glenn Andressen on March 20, 2009 at 3:57pm

What I found was happening on the longer .040 bends, i.e., the rudder spar doublers, was they were ending up curved. Tossing this back and forth with some other builders online, we established this was because the bend plate was pulling away from the back plate during the bend, that is the hinge was flexing and pulling away.

I did the following:
1. Replaced the original aluminium hinge with a steel one
2. tack welded every knuckle to the bend and backing plates, then ground them flush
3. all thicker material was cut at least an inch wider than the required finished flange, then trimmed.
4. stopped trying to bend anything over 40 thou!

The brake Ron describes of Larry's design would be great, but I have limited space where we are living at the moment, so a brake fixed to the edge of the bench was the best solution.

Attached photo show where the hinge was pulling and where I later tack welded the new hinge.

Attachments:

• P1040284.JPG, 220 KB

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Permalink Reply by Grant Arthur on March 20, 2009 at 6:29pm

Thanks again for the great info Glen. I will keep this in mind, I am currently building my work table tonight. I have had my plans for a week and I felt like I had let a year pass since I helped this project progress. :)

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Permalink Reply by Ron Lendon on March 18, 2009 at 9:46pm

Grant,

Larry McFarland has plans he sells and if you complete it and send him a picture he refunds your money. It looks pretty strong to me. For $35 for the plans $600 for materials and some sweat equity, you can have the grandaddy leaf break that will build your airplane and many other things.

Check out his website http://www.macsmachine.com/

Click on Bend Brake in the lower left hand menu.

Later,

Ron Lendon

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