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Longeron downward bend

Arie

Arie

Well Known Member
Good day
I need to make the sharp downward bend in the longerons, but I have a few questions before I mess one up.
1. Do you need to off set the bend line ,to allow for a bit of a bend radius at the 28 1/4 mark ( the start of the downward bend). I think to clamp the longeron in my vice about 1/8 inch aft of where the sharp bend must be formed. I hope that the bend will then start slightly forward ( 1/8 of an inch) of where I clamp it.

2. I guess that you need to hit it with a rubber hammer as close to the vice as possible.

3. What happens to the vertical flange of the longeron as you bend down in the vice, the verical flange would then be in compression and surely the metal must go somewhere. Hopefully it will not cause a bulge at that point.

Maybe I am over thinking it?
 
If you have a piece of scrap angle, you can practice a bend and compare it to the side skin that is pre cut for that angle, that's how I matched mine up, it is not much of a bend.
 
Arie said:
Good day
I need to make the sharp downward bend in the longerons, but I have a few questions before I mess one up.
1. Do you need to off set the bend line ,to allow for a bit of a bend radius at the 28 1/4 mark ( the start of the downward bend). I think to clamp the longeron in my vice about 1/8 inch aft of where the sharp bend must be formed. I hope that the bend will then start slightly forward ( 1/8 of an inch) of where I clamp it.

2. I guess that you need to hit it with a rubber hammer as close to the vice as possible.

3. What happens to the vertical flange of the longeron as you bend down in the vice, the verical flange would then be in compression and surely the metal must go somewhere. Hopefully it will not cause a bulge at that point.

Maybe I am over thinking it?
Click to expand...

IIRC, the longerons fabricated per plans are slightly longer than they need to be, and I don't think 1/8" one way or the other on that bend location will matter much. I seem to remember matching the resultant bend to the side skin, then having to trim the ends slightly. To keep the vertical faces from bulging out of plane, do the downward bend with the longerons clamped together back to back. http://mykitlog.com/users/display_l...project=2052&category=7420&log=186449&row=170

FP16022014A00014.jpg
 
I just clamped it at the line and tried to hit it with the hammer close to the vice but it's difficult to get real close. Some radius is ok. I didn't bend mine enough so I had to tweak it some after it was installed. I just put some pressure on the longeron, got it in position, clamped, then drilled gradually working my way forward. Both of my longeron were about 1/4" too long so they had to be trimmed. I also had to adjust the twist. I used two large Cresent wrenches, one to stop the aft portion from twisting and the other to put in the forward twist.
 
Thanx guys.
I followed the plans and your tips today, and they came out perfect. Both longerons are within 1/64 of an inch of each other. I dont know why I was sterssing about it so much .Totally non eventfull !!.... Well easy to say after the fact....
 
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