Machinist question

[caveman]

Don, I'm no machinist, but you might want to try a product called "Never Seize" you can find at automotive parts houses, it's a silvery colored stuff you can brush on threads that are subjected to high heat, like exhaust bolts.....works great & does exactly what it says, a little on a cue tip in each tapped hole before heat treatment may brighten your day from now on......

[Nifmakr]

Don,
If you have an ajustable 4-40 die, you can also adjust it to cut the threads slightly undersize to fit the holes. Then if you get a sloppy fit, you can take another screw and back the die back out and get a perfect fit. Most all tool steel, SS and carbon, shrink slightly during heat-treat. And a few expand slightly.
Sorry I didn't see this sooner.

Steve

[tom mayo]

seems to me all of you are way too smart.............why cant you just run the threads of the screws on a dull 400 grit belt so they are a bit smaller??????????????

[Colin KC]

Because we're way too smart

[Colin KC]

Smarty pants

[Nifmakr]

Tom,
It's not necesisarily the outside of the thread holding it off but the littlebitty grooves that are keeping it from threading in.

Steve

[Colin KC]

See, someone even smarter

[tom mayo]

Hes from the hills in Tennessee, he doesnt know nothin'!

[Nifmakr]

"Pot calling the Kettle black".

Steve

[Ken Onion]

I have also had this problem in the past the best and simplest thing to do is to get a couple of carbide drill bits from 1/8-3/16and a 3/16 carbide reamer and drill out your tapped holes and ream to 3/16 then buy or make a couple of 3/16 straight folder pivot tubes that are already threaded and insert into the holes in your blade trim excess length and you are back in business .these tubes are usually threaded to 6-32 but you will find the occasional 4-40 . Good luck!

[Don Cowles]

Thanks, Ken. In this case, I did wind up just drilling them out with a carbide bit and using pins on the scales. I have also bought some oversize 4-40 taps. The threaded tube is a good solution.

[Bob Warner]

I have a question.

If you were to run screws into the tapped holes and left them there during heat treat, do you think you could get them out afterwards?

I see several possible answers here but I really don't know what would happen.

They could be stuck there forever.
They could shrink more than the hole and fall out.
They could not change and the holes shrink around them and deform the holes.
They could weld to the tang.
They could be removed and new screws fit perfectly.

Any speculation as to what would REALLY happen?

[Don Cowles]

Bob, let us know what happens when *you* try it. :evil

[Bob Warner]

And I was hoping for an educated guess, instead I get homework.

[Geno]

A bi-matalic fit up should not weld, for example S/S screws and C/S blade.
The holes could shrink around the screw, worst case senerio.
Black soot fron acetylene can coat the screws to ensure no fusion occures inside the holes.
S/S should not be affected by the heating and cooling processes,
The tang holes can be.
I use threaded barrels and drive them into the tang for threads.
Havn't lost a tap sinse I started this way."IF" the threads got buggered up, just knock it out and replace the barrel instead.
(Unicorp in New Jersy-800 526 1389 has these fittings)
(they are called threaeded stand offs)
Heat treating with screws in place is not a good idea, just asking for extra problems.
It depends most on what kind of screw you put in what kind of steel, of what would happen.My best suggestion-Don't.
Don, try these fittings and see if they help.
I use the P105's in S/S with a 2-56 thread.
It just may eliminate this problem forever.
Be blessed.