What is it?

Found these when cleaning out my tool box this past weekend from my machine shop days. They came with a group of tools I purchased, never used them but thought they were neat.

I’m sure they are for measuring spindle speed, just wondering if someone can shed some light on their exact use.

They smell like 1970.

Dam your old

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Grandpa has a tool similiar to that, that he uses on old tractor for PTO output speed.

turbo2387 said:

Grandpa has a tool similiar to that, that he uses on old tractor for PTO output speed.

Click to expand...

Interesting use and good idea. Being we have a tractor with a non-working tach.

I've been stuck in one machine shop or another for over 40 years and have not seen one of those. Very cool.