Spoiler Alert!

This post is going to have a lot of words and few pictures, I'll try not to write a novel, but no promises.  I'm a bit disappointed that I didn't take pictures of this process because it worked really well. 

Originally I bought an Uzi receiver flat with the intention of making a bending jig like I did with the AK.  But after reading up on it, it's not a straight square bend like the AK, the nose section of the receiver has to wrap into a tube.  I wanted to reuse my original front end and Hebrew marked rear section anyway and I decided it would be a shame to cut apart a $70 receiver flat just for the bits I needed.  So I decided to do it the hard way.

Spoiler Alert!  I have a CNC mill.  It is not big, and it is not fast, but it gets the job done.  It's a Seig X2D that I converted to CNC myself.  Maybe some day I'll give it it's own build thread.

I decided to make my receiver section on the CNC.  Why?  Because I have way too much time on my hands, apparently.  It seemed like a good idea at the time.  More important than why is how? How do you make a .070" thick sheetmetal part on a CNC mill?  Milling it from a solid block of steel would be way harder than it sounds because as the walls get thin the part looses rigidity and the side walls want to get either pushed away from or pulled into the cutter, making a vibrating mess with no chance of holding a tolerance.  So that method is out.

I decided to think more outside the box.  And into the tube.  I got some 2"x2"x3/16" wall steel tubing.  I'm using A500 grade tubing, which is about equivalent to 1020 carbon steel.  It might seem like it would be too weak for a receiver, but it's stronger than the 1010 steel used in the commercially available receivers(and flats like the one I bought).  Like the AK, the sheetmetal of an Uzi receiver doesn't see much load, so all it really has to do is hold the parts in.

So, how did I make 2" square, 3/16" heavy wall tubing into a 1.6" wide, thin sheetmetal piece?  I cheated, obviously.  This is the bit I'm kinda proud of, and I'm sorry I don't have any pictures of it.  After drawing up a CAD file based on measurements of my receiver pieces and available blueprints, what I did was machine the the sides of the receiver into the sides of the tubing, cut the middle out, weld the halves together, then machine the bottom.  In the pic of my mill above, I'm just finishing up the finish facing pass to get the bottom thickness set.  My welding jig to put the halves together was just a bar of aluminum cut to the right size, and it also served as a backer to support the thin sheetmetal sections so they wouldn't collapse in the vice for the last milling operation.  I elected not to cut the ejection port until later too so that the piece had a bit more stability while milling.  The holes for the blocking bar welds are sloppy as heck because I forgot them in the program and just used my mill as a drill press and I suck at hand drilling holes.  I'm not too concerned, they get welded over anyway.  Here's what I ended up with, one CNC made sheetmetal receiver section.