# What do you think these are?



## randyjaco (Jan 5, 2013)

I picked these up today. I purchased a lot of used tooling from the  widow of an old machinist. It was a mixture of fine old Starrett stuff  to some late model Chicom crap. 
These were bagged up separately.  They don't look like they were shop made. There is no maker mark or any  other marking on them. The profile is a stepped triangle.  Each is bored  3/8" thru with brass thumb screws which would secure the triangles to a  3/8 rod. One has a second parallel threaded hole about half way through.  The largest flat surface has a steel ball attached to it.
I am  thinking it is some type of trammel for measuring the distance between  bolt holes, but that is just a guess. Does anybody know what these are?

Randy


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## 7HC (Jan 5, 2013)

Dunno, but they definitely look like they're part of something else, or attachments for something expensive.


M


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## 4GSR (Jan 5, 2013)

Randy,

Those are for checking ring groove diameters on API ring grooves in high pressure flanges.  It is missing a rod like a piece of drill rod.  They probably can be used for checking dovetails to some extent.  But originally for checking API ring grooves.

This is called cameron ball gage.  The newer one's are shaped slightly different from the one you have but still the same instrument.  Here's is a link to their website.


http://www.ballgage.com/


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## Tony Wells (Jan 5, 2013)

Ken is right. BX ring groves in flange faces for one example. Fit the balls in the angle-sided grooves, snug them on the rod, and measure over them. Subtract one ball diameter and you have the centerline diameter of the groove. Used a set many times.


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## randyjaco (Jan 5, 2013)

Thanks Ken and Tony,

I believe you are dead on. The BallGauge pictures match up and the place I got them was definitely oil country )

Randy


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## Hawkeye (Jan 5, 2013)

I'm thinking they would hold a dial indicator in the 3/8" hole. The ball would fit into a clamping socket so the DI could be positioned easily. Not as easily as the newer one-knob arms, but maybe good for the day.

Edit: I should mention that I spent the last few hours down in the shop. This forum software doesn't warn you that someone else has posted, so my wrong guess is now a matter of record. :biggrin:


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