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Explain This Sine Bar

Dick Streff

Sep 12, 2003
Picked up this 10” sine bar some time ago in a miscellaneous batch of tooling. I understand the basic functions of sine bars, but I don’t understand the clamp type addition on the end missing the roll.

The bar was made by Machine Products Corp. of Detroit. It appears they were makers of precision measuring equipment with a line of angle plates, v-blocks, etc.

It is drilled to allow another 1” roll to be screwed on the end missing one. Not sure why the roll installed is about 1/2” wider than the bar on one side.

Anyone seen a sine bar like this and can explain the construction?





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Hot Rolled
Nov 22, 2015
San Francisco
Speculating here.
Not that I've used one this way frequently, but at very steep angles the pile of blocks your sine bar sits on start to interfere with the bar. That would let you put the blocks to the side.
Maybe there was some sort of fixture the pin would go in to?
Is there a situation where you would indicate off the top of the pin instead of just knowing where the bottom sits?

dana gear

Hot Rolled
Feb 27, 2013
Northern califorina, usa
Most of my Sine blocks are Navy from the now closed Hunters point naval shipyard.
Most of them have the round wider than the sine bar body, some protrude out one side only others both sides.
There have been a few times that having a protruding round has come in handy.
I can't help you ID your sine bar although we did have something like it here years ago on a machine for setting it up, it attached to a fixed section on the bed of the machine. Maintaining precision measurement with a clap arrangement took great care.