> You could have for example a 12-sided bolt in-between the
> lugs themselves, as that area doesn't touch anything. It
> may look funny but there's no need to make it *perfectly*
> rounded on those non-bearing surfaces.
Absolutely. You make as many cuts as you need until it clears the trunnion and satisfies your esthetics, then move on to the next operation.
"That's not a pentagram! That's a circle!"
"A circle *is* a pentagram, for high values of five."
- Rick Cook
> ETA the only cut that concerns me is the matching angled
> cut in the trunion. Still can't picture how that gets all done
> up pretty.
I've stared at a few trunnions, looked at the marks, and I am 100% convinced the compound angles were cut freehand with a die grinder. As long as the bolt doesn't get hung up on a corner inside the trunnion, the angles appear to be noncritical.
It's stuff like that that makes me stand back and admire the genius of the AK design. Anyone can design a rifle that requires a bunch of custom tooling and precision machining; designing something that can be made with ordinary tools with few critical dimensions... that's a whole different thing.
No Hope For Me
I think the lugs on a trunion are cut with a long end mill through te bore with the trunion set up at the aproperite angle.
My guestion is if were going to make it from scratch why geep the lugs at all differant heights?? the angle I undersand I dont get the uneven lug heights from the face of the trunion.
Well, well, well, my droogies... there's nothing like making a fool of yourself in public for getting a "leaning experience"...
I just looked at a Romanian and a Yugo bolt. What I had ass-umed were curved cuts on the locking lugs are just flats, with the corners rounded over, looks like hand work to me.
The left side locking lug is just a rectangle with two opposing corners clipped off.
The right side locking lug just has the back corner clipped off.
The bolt carrier lug is a parallelogram with the front corners rounded over into a curve and the others corners rounded off slightly.
The Yugo bolt is in the white. It looks like the quarter-round shape of the right locking lug was made by turning the bolt at a 45 degree or so angle and rotating it under a grinding wheel. You can see where the corners of the lugs had the leftover "fins" cut away after shaping the quarter-round.
So, there were no fancy cam operations involved in making an AK bolt. It's just straight cuts and some hand work.
Now I know I can machine this thing. The next step is to figure out a heat treat.
Hmm. The cross-sectional area of the bolt seems to be fairly constant, good for deep heat treat. Google says 4140 is used for bolts from Weatherby, Smith & Wesson, and others, so it looks like a safe choice.
Heat treating ferrous metals is a huge subject, but a generic 4140 heat treat is heat to 1550-1575F, hold 3 to 4 minutes, quench in oil (agitation recommended), then draw back to the desired hardness. I found cites for 44-45 Rb and 42 Rc; there's a draw chart at Heat Treating Toolsteel - Tips - Techniques & Useful Information
What advantages would that give over the stock AK layout?
Originally Posted by rbthntr64
tired of idiots
I was told by a manufacturer that ar bolts are made of CARPENTER STEEL. I have the RC around here in an email, IIRC it was in the mid to high *EDIT* I do remember it was higher then you could reliably get with 4140
ak lugs are square.
I have used a cheap file on a victornox multi tool to EASILY round the corner of an AK bolt before.
EDIT see post on page 6 for specs.
Last edited by vz58; 01-08-2010 at 02:16 AM.
OK I give up, what's Carpenter Steel?
Where did you get the 4140? I have some 4340 and it is HARD STUFF out of the box.
No Hope For Me