What Is It

[catmechanic47]

I recently got in on the tail end of a estate sale and picked up a nice set of 5c collets and some other goodies. They threw in a box of other stuff, but I can't figure out what it is. There are five very similar boring head looking pieces, but no two are alike. The guy really did some nice work. Too bad I didn't get to pick his brain. Any ideas on this stuff?

 

[barnett]

Nice score !!

 

[tertiaryjim]

Don't know what those heads are for.
Are the shanks 3/4 " Dia.
The double screw could be for precision adjustment. What pitch does each screw have?
If the outer screw had a pitch of 20 tpi it would advance 0.050" each rotation.
With a inner screw pitch of 25 it would retract into the outer screw 0.040" leaving just a 0.010" advance of the tool per rotation.

 

[janvanruth]

must be some sort of toolholders with a fine adjustement as tertiaryjim states
for a turret lathe?

 

[Tony Wells]

That's called a differential screw. Looks like someone was building a boring head or something.

 

[tertiaryjim]

Differential Screw. Thanks! Couldn't think of the proper name.

 

[catmechanic47]

That's called a differential screw. Looks like someone was building a boring head or something.

Thanks for the clarifacation of terminolgy, and yes it is. If I remember right, it was 24 and 26 TPI. As much as they resemble boring heads none of them have a place for a cutter. I'm leaning toward some kind of a holding fixture. All had 1" shanks. Two of them had incremental scales around adjustment screw, which doesn't make sense for a holding fixture.

 

[kd4gij]

I know what thay are, but it is top secret. If I where to tell you the black hellacopters would be out in full force.

 

[C&I Harry]

Looks like tools to do accurate inner groove cutting.....

 

[T Bredehoft]

Or, perhaps they hadn't gotten to placing a tool. That would make an awesome boring bar holder, but with minimal adjustment. I've saved the images and some of the discussion, with the thought of adapting it to a boring bar.