Compass? Dividers? Old tool question

[Jim K Jordan]

I picked this up at a flea market. It's a screw adjusted compass?
It was missing the adjustable point, I made one out of a carbide burr.
Interesting design, the cone point is spring loaded looks like it may be some watch/clockmaker tool.
Works good for scribing radii from a center hole up to 3/16"
The knob on the left is the adjustment screw.
Nice old style rope knurling on the screwheads.
The main beam is triangular.
I've never seen another like it.
Any idea what it is called or what it was made for?
Jim

[Rick U.]

If this were mine, I would use it to enlarge gem stone setting holes that were plotted in a circle, so as to maintain equidistant appearance.  With this aid, it would be far easier to accurately cut the established opening to the desired depth for each individual (and differently dimensioned) gem, prior to establishing, setting and beading prongs.  Excellent find my friend!

Can the cutting burr be changes and have you thought of fitting this into the chuck of a drill press WITHOUT TURNING IT ON, and using the press as an extra hand?

[Jim K Jordan]

Yes, the center cone is spring loaded. It isn't a cutter, but could be. The adjustable point could changed too.

If the cone position was able to rotate with the handle as a pin vise, that would work.

My understanding is originally it had a knife like blade and was used for cutting gaskets or scribing circles off of a center hole.

[David Giulietti]

My first thought was a variation on trammel points or a beam compass. But given the hefty handle, the steep angle of the (center finding) center point, and the short beam I would guess gasket cutter. Google images seemed to agree.

My 2 cents

David