Curious Slocomb Bore Gauges

wheels17 · Jan 27, 2021

Another Tool Thrift Shop curiosity. I have never seen what I think are bore gauges like these, and we had two different ones come in within two weeks. They are manufactured by J T Slocomb:

There is no spring action to the measuring rod, and the nut used to adjust the position has graduations but there is no index mark:

Only one has a makers mark:

The handles do turn and allow locking of the measuring rod, but if you are inserting them into a bore and turning the nut until you get the feel you need, why are there graduations on the nut? Or am I completely misunderstanding the use of this tool?

rivett608 · Jan 27, 2021

Those are Slocomb’s inside micrometers. They made them in the two sizes you have. They were fitted in cases like the little one or both in the same case. They bought the patent/design from some other company I think but can’t remember who.

rivett608 · Jan 28, 2021

According to Cope this was the Sept 21 1909 patent by Henry S. Plant. It was first produced by the Emerson Apparatus Co. of Boston, Ma.

jim rozen · Jan 28, 2021

Great answers guys, but the question remains:

Where's the darn INDEX mark?

wheels17 · Feb 2, 2021

I had to buy them. They aren't quite as convenient as conventional telescoping bore gauges. I tried them on a number of well known hole sizes, and they gave good results. Slow, but the point at which they would trip through the hole was very clear.

I can see them as very handy with a preset size for testing as you sneak up on a bore diameter.

But no index mark.....

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Curious Slocomb Bore Gauges

wheels17

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rivett608

Diamond

rivett608

Diamond

jim rozen

Diamond

wheels17

Stainless

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