Whatzit machine or tool?

Got this cheap at our semi-annual machinist club yard sale. No idea what it is for but when top knob is turned, the two rings move closer together or further away from each other depending on direction of turning. The top mechanism moves across the frame when the other knob is turned. Wot du dis du?

 

Is it possible to change the angle of the upright piece where the rings move?

 

Does the piece at the top of this assembly move/do anything?

 

No, only twists.

 

No

 

The steel thumbscrew can be turned to tighten on whatever is put in the ring. The whole brass L shaped bracket moves up or down as the top knob is twisted.

 

is there a thumbscrew missing on the 2nd ring..?
could the rings hold something in place for engraving.......
the base looks to be 8 x 4 ...and reasonably heavy...or solid.

 

Purpose does seem like it is meant to hold something securely, but still repositionable. Are both holes the same size & shape? Why would this little cut out be needed?

 

seems the rod would have at least one right angle.

or not.....

 

Motion is hard to put into words. I can't picture what this means. The dark colored upper piece moves to & from where? In what direction relative to other elements?

 

A vise for drilling angled holes in round stock. That's my guess

 

Is the match for this screw lost or is the only one from the beginning? What is it holding/what is allowed to move if it is loosened?

Edit: Duh. Completely meaningless without the pic that was supposed to be with it.

 

Looking again, think I figured it out: it is the whole contraption that moves forward/back or side to side, no?

 

Hmmm, let’s try this.



a. Iron frame, screws to something long gone.
b. Spindle assembly
c. Upper arm
d. Lower arm
e. Horizontal movement knob, makes entire b. Move right or left in this picture. B remains at constant angle with a.
f. Knob making c and d. Get closer together or further apart, Depending on direction turned.

There is no place for a thumbscrew in the ring at end of c.

 

Yes, that is nice & clear. Sorry for making so much work for you. I edited post 15 & added the relevant photo. Asking about a different bit.

 

That screw is what in the Navy would be called a “DFW screw.” It was put there and adjusted at the factory or depot and woe be onto anyone who F’s with it. In this case the tightened screw is there to prevent axial motion of the brass guide-shaft.