I hate machining steel.

Now for the hardest part of my "doing it the hard way" Uzi project, the bolt.  There are a lot of differences between semi-auto and full auto Uzi bolts, primarily because of the striker instead of the fixed firing pin.  I could have bought a factory semi-auto bolt, or I could have modified my original bolt, but as previously discussed, I'm an idiot and apparently a glutton for punishment.  I decided to just make my own.

I made a CAD model of my FA Uzi bolt, then added the necessary modifications for semi-auto use so that I could CNC machine it.  The factory Uzi bolt is 4130 steel, but I decided to make mine out of A2 tool steel.  I chose A2 because it machines alright, it's very tough without being too brittle, and most importantly, I have a large chunk of it.

I hate machining steel.  Nothing about it is any fun.  It's hard on cutters, it's painfully slow compared to aluminum, and the chips are tiny little razors just waiting to bury themselves in your skin.  I'm also used to machining aluminum but very little steel(and even less hardened steel) so I run steel very conservatively.  My little CNC mill is not fast, and it is not powerful, I could never run aluminum at the speeds I'm used to.  But for steel, I don't need high speed anyway so it works out alright.  I use carbide endmills for everything because life is too short for high speed steel, and even good carbide is cheap these days.  Also machining high speed steel with high speed steel cutters is likely just going to chew up cutters so carbide is cheaper in the long run.

My new bolt is going to take 5 setups to machine, basically machine a side, turn it in the vice, machine the next side, and so on.  I don't need to machine the top because it's already flat.  After several hours of painfully slow machining, it's starting to look like something.

Operation 1, the right side:

Operation 2, the bottom:

Operation 3, the left side:

The last two ops are the important ones, and also the most nerve wracking, so stay tuned.  Same Bat time, same Bat channel!

More spoilers

Another post full of spoilers.  First, I have a 3D printer(two actually, but who's counting).  Not really that big a deal, lots of people have them.  Second, I have a 3D scanner.  It is not the world's greatest scanner, but it works for my needs.  And what I needs now are some grips for my Uzi.

I was not happy with the grips that came with my parts kit.  The pistol grips were ok-ish, but the foregrips were just beat to death.  Scuffed and scraped with half the ribs worn off.  I definitely needed something better.  I bought some original "Excellent condition" grips from a vendor and they were better, but definitely still used.

I decided that I wanted to 3D print some new grips, but there is only one CAD file that I could find that was even remotely accurate looking, and it's proportions were so far off that the parts could not be made to fit the real gun.  And that's where the 3D scanner comes in.  Usually I scan people to 3D print mini versions of them so my scanner isn't great with small objects, but it's good enough for my needs.  The actual scanning doesn't take long at all, but there is a lot of post process clean up with involved.  To be honest, it probably would have been faster for me to just redraw them in Solidworks, but this whole project has been an exercise in doing things the hard way.

Anyway, here's what I ended up with.  I printed them in blue because only the cool kids have blue handguards.  Deal with it.  Actually, these are essentially my "rough draft" prints and blue is what happened to be in the printer at the moment.

Overall they fit ok, but not quite perfect, so I'm going to do some more editing of the STLs before reprinting them in black.  I'm not quite happy with the texture on some of the ribs either, so I'll fix that while I'm at it too.  And, not that I'm counting because it doesn't matter for a pistol build, these handguards would count as a US part for 922r.