Bushing to step barrel diameter up to the Romanian trunnion ID. The interference is .003" to the barrel. 3/8" threaded rod to pull them together.
So I'm an idiot who can't read his own drawings... I didn't get the step distance right in the bushing, so I had to press everything back apart. Which meant making a press block and a pusher first.
There were a couple of pieces of grotty steel I had failed to throw out, suitable for a one-shot tool like this. Of course, I put more work into squaring and flycutting than it was worth...
Last edited by TRX; 07-10-2010 at 04:25 PM.
I found an SKS underfolder bayonet at a reasonable price and tried it with the Chinese AK trunnion. No go; the sleeve is about 5/8" too short to engage the lugs. This is a 1966 military FSB, so I don't know if the Polytech ones are the same.
I found up with one complete bayonet and three sleeves and springs. I think I'll splice two of the sleeves together to make one longer sleeve. If I can find someone who can make pretty a fish-scale TIG weld across the knurled sections where the join will have to be I'll do it, otherwide it'll probably get MIGged and some cover-up lathe work to hide the mess.
I went with the spike bayonet. The knife bayonet just didn't look right, for some reason.
No other progress; Real Life(tm) has been keeping me too busy for much quality time out in the shop.
In our last thrilling installment, I found that an SKS bayonet won't fit an AK underfolder FSB.
Just a moment ago I found the picture below. The text near where I found it mentioned it was an add-on bayonet lug for an SKS, and that the author had used it to attach an SKS bayonet to his AK. Note the standard AK FSB.
I just spent twenty minutes trying to find out who might sell those, but any combination including both "SKS" and "lug" just kept turning up bipod mounts.
Anyone know who might sell one of these? I could make one, but if it's cheap enough I'll just buy one and move on to the next thing.