#10-72 thread

[foleda]

I recently purchased a #10-72 die because the absurdity of it appealed to me, and it was cheap.
Has anyone ever seen such a thread in the wild?
#10-32 SHCS for scale.

Now I just need to find the matching tap and I can make some very fine adjusters, or some very slow screw drives.

 

[RJSakowski]

You could always single point the internal threads.

But if you decide not to,

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[Watchwatch]

Yeah

I made a dogmeat repeato meter. Copied the idea from Tom Lipton. 4inch steel disc with a .0001 indicator in the middle. 3 leveling screws on the OD. 10-72 or something to that effect. I bought them off McMaster Carr and the matching threaded bushing.

The fine pitch makes it simple to zero on the surface plate. I really need to fool around with the .000002 indicator I accidentally won on EBay for $20.


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[foleda]

You could always single point the internal threads.

Do I detect a challenge?

I hadn't thought about single pointing them until I read your comment, then I thought "Why not?" After sleeping on it "Why not?" morphed into "That might be fun." So....

 

[FanMan]

Never seen a 10-72, but I've been using (specifying, not making myself) 1/4-80 threads for fine tool adjustments on the production machinery I design. Then we (EDM) slit the female part and put a clamping collar around the outside to lock the adjustment down once it's set.

 

[Flyinfool]

The finest thread I have ever played with was a #4-256. the thread was barly visible to the naked eye. It was on a tiny carburetor for setting fuel mixture.

 

[Shootymacshootface]

The finest thread I have ever played with was a #4-256. the thread was barly visible to the naked eye. It was on a tiny carburetor for setting fuel mixture.

Thats pretty wild!
No overshooting your adjustment with a screw like that.

 

[whitmore]

The finest thread I have ever played with was a #4-256. the thread was barly visible to the naked eye. It was on a tiny carburetor for setting fuel mixture.

Miniature work is so specialized, though; I've always done fine adjustments with differential
screws , like, 1/4-20 on end A of a rod, 1/4-28 on end B, so turning the threaded rod
pulls/pushes two female-threaded barrel nuts by 1/70 inch per turn. For really
fine work, you could make it 12-24 on one end, and M6x1 on the other,
which gives 435 turns per inch (though, of course, 435 turns will require you
to thread a LONG length of rod...).

The best thing about differential screws is, you get LOTS of quick options if there's a big
drawer of taps and dies available....

 

[whitmore]

I've always done fine adjustments with differential
screws , like, 1/4-20 on end A of a rod, 1/4-28 on end B, so turning the threaded rod
pulls/pushes two female-threaded barrel nuts by 1/70 inch per turn.

One pairing I've wanted to try, is 1/4-20 and 1/4-25 (which would make ten mils
progress per turn, 100 turns per inch); there's standard 1/2-20 taps and dies, so one
could also make a 'rod' internally tapped for 1/4-25, externally threaded for 1/2-20,
which would take less space.

It's a nice notion, except that there's no off-the-shelf -25 tpi taps or dies, and I don't
have a screw-cutting lathe available.

 

[TIM-RANEY]

I have gone down only to 10-64 after finding some very nice stainless steel thumb screws at a surplus place. Bought a tap and die at Victor Machinery Exchange...very reasonable. For finer work, I have machined coaxial differential adjusting screws. One was equivalent to 480 TPI with a linear travel of 0.0508mm or ~2 x 10^-3 inches per revolution. I used 30 and 32 TPI. All tap and die work....no single pointing on the lathe.