Machining brass I beams.

[tirebiter]

I am needing a source that can machine brass I beams from .250" to .500" high. Smaller I beams are comercially available but I am having trouble finding a source for the size I need. I thought I could produce these myself but I am under the impression that a dual spindle machine is used to cut both sides at the same time to keep the warping under control. Any help will be greatly appreciated.
Thanks
Steve

[RICHARD ZASTROW]

What is the length of beams?

[jetski]

Jabro use to make cutters for I beam shaped wing spars. The way they did it is with a machine called a Modig. The cutters were one flute rh helix and one flute lh helix. This would cause one to pull and the other to push as it cuts. This would keep the aluminum neutral durring the cut. The modig was a 5 axis machine that used 2 rotary tables on the x axis (A axis) and an aux U axis to move one of the rotary tables (both tables parallel to the x axis) to feed the material much like you would through to hands. I had a chance to work one of them for a while. A machine no bigger than a standard cnc mill could cut a 60' wing spar. There are several specialty cutters that could be used befor you go to the expense of a second spindle.

[tirebiter]

The max length that I need is 14". This is for a .25" * .5" I beam. I need at least 50 feet of this size.

[RICHARD ZASTROW]

Steve, Assuming this is not a regular production job, you may consider making a "rack vice fixture" or "rack vice jaws". Mill a slot in the fixture that will accomodate the stock with some clamping screws or a slot between extended vice jaws slightly undersized so stock can be clamped. Clamp the stock in the fixture, mill one side, remove stock and rotate 180 degrees, clamp and tap down , mill second side. Equal removal brom both sides should cancel out opposing stress. Any deformation left should be easily pressed out.

add: There is a 20" stroke, opposing spindle, "spline miller" that uses 2 end mills to cut splines and opposed keyways. It's either listed on the used machinery sites or ebay and I don,t remember where.

[tirebiter]

Hi Richard,
Thanks for the info. If I can't find someone to do this I will try to make a jig.
Thanks
Steve Paul

[tirebiter]

What type of cutters are you referring to? Thanks in advance.
Steve

[jetski]

They have a web site I think it is Jabro.com I do not remember what the cutters were called. If you call them and discribe the left and right helix for aluminum they will be able to pull something up. In the case that it is no longer made. Send me an email and I will talk to the guy who use to do the programming.

gsilberberg@progressive-plastics.net

[tirebiter]

Thanks Richard,
Your suggestions on clamping and fixturing worked. I made a small fixture to cut a smaller I beam to test the principal. It worked perfectlly. I will make a larger fixture to machine the larger size.
Thanks again,
Steve