Creator: Orion's Hammer

3D Printable Semi-Auto AK47 Fire Control Group (FCG) Parts

   Yes, these count as 922(r) "Made in USA" compliance parts!

  By Orion's Hammer -- [email protected]

  Free to use, modify, and distribute for any *legal* purpose

Print these at 100% infill, with support material.  Units are mm.

  "model_simple" is from FreeCAD, and has straight flat sides.

  "model_complex" is from Autodesk Inventor, and has chamfers and curves.

  Both are complete hammer-trigger-disconnector sets, and they print and fire successfully.

CAUTIONS:

- Plastic is not as strong as any metal, and it can't take much abuse.  In particular, putting the safety on and pulling the trigger really hard *will* bend or break the trigger, possibly firing the gun.

- Plastic tends to 'creep' under sustained stress, and in particular the trigger hooks are under constant stress anytime the rifle is cocked.  I'd expect the hooks to slowly open up while cocked, possibly enough to let the hammer go and SPONTANEOUSLY FIRE THE GUN even with the safety on.  This isn't a problem if you carry and store the gun with hammer down on an empty chamber, and doesn't seem to be a problem after a few months in cold storage, but a chambered and cocked gun could be deadly, especially in a hot environment like a car in the sun (creep is temperature dependent, and ABS softens noticably at about 200 deg F).

- The interior holes seem to print smaller than shown in CAD, so I need to drill each parts' axis pin hole out with a #7 drill bit (5.1mm), and the disconnector with a #20 drill bit (4.1mm).  This leaves a cleaner hole than anything I can print, and I don't even have to measure the hole location, I just let the drill bit follow the existing undersized hole, so it only takes five minutes.  This would certainly be more repeatable with a drill jig, but print-and-drill works fine.