What is it?

randyjaco

randyjaco

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I got these triangular gizmos as part of a box purchase. They have a ball affixed to the bottom. I added a half inch rod which makes me think that they might some kind of bolt hole spacing measurement device. There are no markings on them. Anybody recognize what they are?
 

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I looked at them carefully and then turned around to look at my south bend dovetail slides that have round holes instead of T slots----I think maybe the sb logo may be on them----are they approx 1/2 " balls?---that is my idea of what they are---I plan to make rods of different lengths with a tapped hole for my two SB slides---DaveDSCF0005.JPGDSCF0001.JPG
 
If two were placed on a rod, they could be used to measure the distance between two holes. I use pin gages but I have to fit the hole size. The balls will accommodate a range of hole sizes.and will even work with chamfered holes. Measure the outside distance between the balls and subtract the ball diameter to get the distance between the holes.
 
They are use to measure the ring grooves in high temp/high pressure pipe flanges, the type that use metal o-rings, known as rtj flanges.
You could adapt them for home shop use by replacing one of the balls with a scribe. Starrett makes a set of trammels like that that use a half ball on one end for marking circles on something that have a hole in the center where you couldn't use the pointed pivot.
 
RobertB said:
They are use to measure the ring grooves in high temp/high pressure pipe flanges, the type that use metal o-rings, known as rtj flanges.
You could adapt them for home shop use by replacing one of the balls with a scribe. Starrett makes a set of trammels like that that use a half ball on one end for marking circles on something that have a hole in the center where you couldn't use the pointed pivot.
Click to expand...

I work in the energy industry, on industrial valves (some with rtj flanges), and even I didn't know this ... wtf?
 
Thanks for the responses. Now I have to figure out what to do with it ;)
 
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