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Wednesday, May 20, 2015

Clever Fixturing For an 80% 1911

Thanks to Wirecutter at  Knuckledraggin' My Life Away, we find a link to a new way of making a 1911 from an 80% frame without a milling machine.  Designed at Stealth Arms, the new fixture, called a Phantom Jig, guides your cutting of the necessary features by hand.  The operations required to complete their version of the 80% frame are to drill a couple of holes, cut the slide rails and the barrel seat.  The Phantom Jig performs the cutting operations that would usually be done on a milling machine.
The jig with a frame in place - when you buy the jig, they include one frame.  Note the long black handle: in operation, you use this like a woodworking plane.  The cutter is lowered into cutting position by the black knob with finger grooves located next to the handle, and the handle is then used to push the cutter forward through the metal taking off - ? - "several thousandths".  The rest of the jig needs to be held in a sturdy vise to handle the forces you're going to generate on it.  Once you make a cut, you advance the cutter 1/10 of a turn of that knob and cut another pass through the frame.

Wirecutter embeds this video, but I didn't watch all of.  It's 45 minutes long - and the video author said it took 40 minutes to finish his frame.  Stealth Arms has a video on the Phantom jig's page showing how this all works. 

I post this because I like clever, and this approach just exudes clever.  If you have even a table top drill press, you can drill the two holes you need to drill.  (Seriously - get a drill press if you don't have one.)  Then all you need is this fixture, a bench vise, an hour, and some good old fashioned elbow grease.  I think I should warn that this fixture isn't going to get you there if you're trying to complete a steel frame.  I think that requires more shear force than you can generate.  Stealth Arms' frames are made of 7000 series aluminum, which is heat treated to a higher hardness than the more-common 6061-T6 "aircraft aluminum".  7075, for example, is used in high-end mountain bikes.

Making a 1911 is pretty high on my list of projects right now, and I'm keeping an eye out for a steel frame.  Since I have a milling machine, and making one without the jig is cheaper, chances are that's the way I'll go. 


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6 comments:

  1. drjimMay 21, 2015 at 12:52 AM

    Keep us posted!

    I'm "this close" to buying the jig and a couple of frames.

    ReplyDelete
  2. AnonymousMay 21, 2015 at 8:53 AM

    It is essentially a hand operated planer-a tool that used to be common in machine shops prior to high speed rotary tools AKA milling machines. With a sharp carbide or HSS cutter it would probably cut steel just fine.

    ReplyDelete
  3. AnonymousMay 23, 2015 at 9:48 AM

    Check out Tactical Machining in Deland. They make 80% 1911 frames and AR 80%.

    ReplyDelete
  4. SiGraybeardMay 23, 2015 at 11:30 AM

    Anon - I was going to say I have Tactical Machining on speed dial, but that's a slight exaggeration. I just have them bookmarked in the browser and visit fairly regularly.

    ReplyDelete
  5. SiGraybeardMay 23, 2015 at 1:46 PM

    To reinforce what Anon 5/21 at 8:53 AM said, here's a YouTube video of a steel Tactical Machining steel frame cut with the Phantom Jig.

    Bottom line: the barrel seat was cut with a mix of the jig and a hand file. The rails were cut entirely with the jig, just as the jig design intended. And the result was a functional 1911 finished without a milling machine.

    ReplyDelete
  6. AnonymousMay 24, 2015 at 4:43 PM

    If you want a nice feature article on how the 1911 was made during wartime, "Machinery" magazine, December 1942, vol.49 number 4 has a nice insert article- machining steps, types and sizes of steel used for every part, etc., Written by Colts production manager, E. Herrick.

    ReplyDelete