Hartford Tool Co. Some kind of gauge?

[Grampz]

Got this at a sale with a bunch of older tools. Wild guess, some kind of ID gauge? Marked "Hartford Tool Co HFD CT USA" The body has a split collet at both ends, one threaded and the other slip. Seems to be made for a range of about 3 1/2" to 4 1/2". Thanks for looking!

Grampz (new guy)



 Never saw one of these but figured it out. the Perfect Pocket Oiler.

[Bill Houghton]

That does look like some kind of gauge for measuring inner diameters - perhaps something used in conjunction with a suitable micrometer, but cheaper than buying a separate inside micrometer (I have two inside mikes; have yet to use either, but, hey, they weren't expensive, one being free, when we cleaned out my uncle's garage).

And that Perfect Pocket Oiler - neat design, although if it leaked, I bet it would do a Perfect job of Oiling your Pocket.

[Plyerman]

I wonder if that first one is for measuring i.d. threads?

[bleonard]

The first tool looks to me like one used by millwrights and repairmen to check the where in a cylinder bore. The tool is adjusted with a ruler to the known bore size and inserted in the bore and rocked side to side. A measurement is taken of the side to side movement and trig. is used to calculate the bore size to the nearest thousand of an inch without the use of a micrometer. This process is described in an older machinery's handbook. But i can't remember which one or where. My two cents worth.
Bob

[Grampz]

That sounds probable. Thanks for the input!