threading help need

[billf]

OK, all you take-down experts and/or machinist types - I'm looking for help in threading a tang - I've made hidden tang (pinned) and full tang knives, now looking to try and make a take-down type hidden tang. I know drill sizes for the various taps, but what size do I round the end of the tang to for threading with a die, say 6-32 or 8-32? Are these good sizes or should I go smaller or bigger?

Thanks for the help guys!

Bill

 

[Karl B. Andersen]

Just so it's not bigger than the slot in your guard. Make sense?
Most of my take-down blades have a ricasso of around .200 after finish. I grind my tang down to about .185 which will allow me to thread for a 10-32.
If I made the blade thinner than .185, I would need to grind the tang thinner and thread 8-32.
Got it?

 

[jdm61]

Hmmm......on the couple i have done, i was always shooting for the ubiquitous 1/4-24, but i realized that even if you have a ricasso that is .250 or a little thicker, by the time you taper out the tang, grind the end round and thread it to at least 75% thread depth, you ain't goinna be at 1/4 anymore. I worry a bit about the tiny threads like 8 or 10-32 count. Does having more threads to contact with the nut make outweigh the fact that the threads are smaller and shallower? i tried one hunter a while back that was threaded 8 32 i think because the nut was a standard 1/4 inch nickel silver blind handle bolt nut. It seemed to work well, but the knife never got finished because the plunge grinds weren't right. Are you using those smaller diameter nuts on your big knives, Mr. KBA?

 

[billf]

Karl

Thanks! I'm actually making an integral from round bar W2, so the "guard" area is set - I don't have to worry about the guard going up the tang! If .185 is good for 10-32, then that's what I'll shoot for - if I go too small by mistake, what do I need for 8-32?

Bill

 

[Karl B. Andersen]

I don't know the dimension for the 8-32 off the top of my head. Get an 8-32 screw and measure it!
As far as strength goes, let's remember that we're just dealing with knives! we're not going to crank down on these like they're lug nuts! Once you get snug - you're done! You don't need to go any past tight! You can tighten it so much you'll collapse your handle material!
Your handle material will fail before the threaded part will. It's a superb assembly.
I only weigh 170, but I turned an 8-32 thread on the end of a 1/2 inch rod and swung back and forth on it while hanging from my garage ceiling.
The finer thread will give you more contact area, as far as stripping goes, but once the number of threads gets up to the diameter of the shaft, that's as strong as it will ever be.
I sometimes intentionally harden my tang, so I have martensite. Then, I draw back the tang so I can tap it - right? With me? If I just left the tang un-hardened, I would have austenite. Tempered martensite is tougher than unhardened austenite. I want my tang to be as tough as I can get it.
It's just how I do it.
Play with it and use what works for you.

 

[jdm61]

Do you turn the pommel nut on your knives on a lathe? That is my next machine, i hope. The couple of knives i have done so far have either used a handle bolt nut or a threaded butcapp, which at that stage of my knifemaking journey, was a real pain to fit...lol. I did 2 like that, and, although they eventually turned out ok, suffice to say that they ended up being smaller in diameter than originally intended...oops!!!

 

[Karl B. Andersen]

Yes, I turn them for each knife.
I turn them so there is a shoulder on the pommel nut that catches an internal "ledge" in the butt cap, or if i'm doing my new style with an insert, there's a ledge in that it also.
That way there's no external scratching going on.