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-   -   Forming the longerons (https://vansairforce.net/community/showthread.php?t=138560)

Allan Stern 06-06-2016 06:43 AM

Quote:

Originally Posted by rvbuilder2002 (Post 1084861)
People mentioning having to beat the *&#@~ out of them, or beat them in to submission never fully understood the desired process (not necessarily their fault.... not everyone will get the same understanding after reading text instructions).

As already mentioned, the hammering part of this process does not entail the use of brute force. It is just a firm wrap to induce the bend to take a set after a bending force has been applied by hand.

Most people that give it a try find that it was a lot simpler than it seemed....

So the "pre loading" is a bend by hand then a set with the hammer? Is that what I am not understanding? Thanks.

Allan Stern 06-06-2016 06:50 AM

Longerons bending
 
Thanks to everyone who has offered help. I am not a novice at this as the 12 is my third RV, however my first two were quick build kits. Any time saving method I can find I try to utilize. I am getting the dies and if I only use them once then I have another tool. I have got a formed left longeron that still needs a little twist that the die will make better.

joedallas 06-06-2016 09:31 AM

Take a look at this page
Step: 02, 03 and 04

This was easy and worked out fine.
about 1.5 hours.

http://joesrv12.com/Builder%20Log/bl_23_02.htm


Quote:

Originally Posted by Allan Stern (Post 1085094)
Thanks to everyone who has offered help. I am not a novice at this as the 12 is my third RV, however my first two were quick build kits. Any time saving method I can find I try to utilize. I am getting the dies and if I only use them once then I have another tool. I have got a formed left longeron that still needs a little twist that the die will make better.


rvbuilder2002 06-06-2016 11:04 AM

Quote:

Originally Posted by Allan Stern (Post 1085091)
So the "pre loading" is a bend by hand then a set with the hammer? Is that what I am not understanding? Thanks.

The pre-load force will not produce any permanent bend, but it will be bending the longeron.
If you remove the pre-load, the angle will go back to the position it previously was.

The pre-load can be applied 24 " from the point the actual bend is desired. The wrap with the dead blow hammer close to the vise is what converts the pre-load into a concentrated bend at the end of the vice jaws.

It has been a while since I bent any longerons but my guess would be that at 24" the desired pre-load deflection would be on the order of 1".

For the sharp bend at the aft end of the longerons (which the bending dies wont do), you can just keep repeating the same bend process as used to make the curve.... keep making small bend increments in the same spot without re-positioning, until you have the desired angle.

BenNabors 06-06-2016 12:53 PM

That is what I did.
 
Quote:

Originally Posted by Allan Stern (Post 1085091)
So the "pre loading" is a bend by hand then a set with the hammer? Is that what I am not understanding? Thanks.

Many people acted like this was a big deal, made me procrastinate on bending the rail. I just applied a slight bend by hand and then set it with a rubber mallet. I spent more time marking the location of where to start and end the bending than I did to bend the rail (along the line of "measure twice -cut once" ;-). I place blue painters tape on the the angle to keep from marring up the aluminum, that worked well. I was worried about the non symmetrical aluminum angle not bending uniformly, but that was total folklore, no issue at all. The is a very gentle bend, noting drastic. Remember that you do not have to bend it all in one pass. Bend it some on the first pass, compare to the interface template and then bend more as needed.
Good luck!

Allan Stern 06-07-2016 06:14 AM

Bending
 
Quote:

Originally Posted by joedallas (Post 1085137)
Take a look at this page
Step: 02, 03 and 04

This was easy and worked out fine.
about 1.5 hours.

http://joesrv12.com/Builder%20Log/bl_23_02.htm

Thanks for the web site. It helps. So you used an arbor press to open up the 5.4 degree longeron before you twist it back to level. I see you used a scrape piece of angle on top and a "pipe" inside the channel during the pressure of press. What size pipe did you use? Thanks.

DaveWelch 06-07-2016 08:19 PM

My experience was that it helped to have a friend apply the pre-load and then I applied the dead blow hammer. Recommend that the pre-load helper wrap the longeron in heavy gloves or towels. Otherwise that first heavy hit is a real zinger on the hands!


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