What is this tool?

[Alex Franke]

My grandfather was a machinist in the early- through mid-1900's, and he worked primarily in optics, making periscopes for various navies. When he died, my father found this object among his things. It has no branding. I'm told that he made it himself, and that the sharp rod with the curve at one end is hardened steel.

The knob on the base rocks the assembly in its slot about 1-2mm on an axis somewhere near the middle of the base. There's a spring under the assembly on the other end (near the larger knob). The other knobs (as you might expect) loosen the instruments and allow it to be positioned.

Any ideas what it might be for?

[Tom Slick]

It looks very similar to a "magnetic base" used by machinists on lathes and mills as well as setting up other machinery.

[Hoover]

I'd hazard a guess, that it was used to measure the accuracy of a ground optic piece.

[cabinetman]

Whatever it is it's beautifully done.
.

[woodturner]

Any ideas what it might be for?

It's a scriber. It's used to scribe a line on a workpiece.

For example, if you have a cube of metal and need a "level line" around it, the metal cube is placed on a surface plate, the scriber is adjusted to the level of the line, and the scriber is moved around the work piece, scribing the line. It scribes a line a fixed distance from the surface plate.

In woodworking, we use a marking guage to do essentially the same thing.

In these links, they call it a "surface guage", so maybe that is the proper term - but we always called them "scribers".
http://www.mini-lathe.com/mini_mill/...out/layout.htm
http://metalwebnews.org/machinist/ch1.html

[Alex Franke]

It's a scriber. It's used to scribe a line on a workpiece.
[snip]
In these links, they call it a "surface guage", so maybe that is the prober term - but we always called them "scribers".
http://www.mini-lathe.com/mini_mill/...out/layout.htm
http://metalwebnews.org/machinist/ch1.html

Ah, that's it! The second link has a drawing that matches almost perfectly!

Thanks a bundle!

[os1kne]

For what it's worth, the one built by your grandfather does appear to be much nicer. That is a very nice piece of craftsmanship.

[gsmittle]

I was gonna say it was a doohickey or a thingamabob.

g.

[rja]

Its a surface gage.

[sscherin]

Wow I have one of those and didn't know what it was for either..

It was part of my Grandfathers tools.. He was a tool and die maker for Western Electric in Indiana.

It's sitting back by the box behind the vices in the blurry zone

[LCHIEN]

Wow I have one of those and didn't know what it was for either..

It was part of my Grandfathers tools.. He was a tool and die maker for Western Electric in Indiana.

It's sitting back by the box behind the vices in the blurry zone

your grandad had a lot of vices.
whoops, i meant vises.