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What is your choice in a Concentricity (Spin Roll) Fixture?

ttrager

Cast Iron
Joined
Jul 23, 2015
Location
East Side / Detroit
If you have Spin Rolls of some kind in your shop to check roundness and concentricity, what do you use and do you like it?

These are Measurement models, not models intended as workholding during grinding.

We currently have several St. Mary's Spin Rolls from Ascension Industries. But back in Oct of 2020 they ran into something at their factory and still, to this day, are MONTHS out from having any more available.


Thanks in Advance.
 
Zero Spindles are nice, but IMO take too much torque to turn. I like the old Federal/Mahr air bearing tables if you can find a decent used one. Not sure how you'd measure roundness with a Spin Roll. Even though intended for grinding, I use my Punch Mate #1 (similar to Harig GrindAll) for measurements because it's really quite good.
 
What diameter of parts? Those St. Mary rollers are nice for big stuff. Can you put it between centers?
Universal Concentricity gauges are nice but mostly for smaller work.
Universal Concentricity Gage

It's been a while since I needed to do a large volume of runout or concentricity measurement, but I had a good experience with the Universal Concentricity Gauges as well.

For really high volume of one specific tight tolerance part and shorter distances I've seen it done with a multi-head air gauge as well, although that's a custom obviously.
 
What diameter of parts? Those St. Mary rollers are nice for big stuff. Can you put it between centers?
Universal Concentricity gauges are nice but mostly for smaller work.
Universal Concentricity Gage

Parts are various in size, but in the case of parts that fit in the St. Mary's, diameters range from .100 to about 1". Maybe a little more in rarer instances. (Don't remember the size boundaries right off hand. For larger stuff you have to back off spring tension to open the roller jaws more).

We like the St. Mary's spin rolls, but some other units, like the Universals, have multiple indicator mounts on them for multi-surface setups.

Thank you for the reply.
 
It's been a while since I needed to do a large volume of runout or concentricity measurement, but I had a good experience with the Universal Concentricity Gauges as well.

For really high volume of one specific tight tolerance part and shorter distances I've seen it done with a multi-head air gauge as well, although that's a custom obviously.

Do you recall the setup or make/model of the air gage?
 
Do you recall the setup or make/model of the air gage?

Unfortunately I didn't spend much time around it, so I don't have the specifics. It was one of the usual gauge suppliers. I'm guessing Edmunds, but could just has easily have been Federal, Adcole, etc. Being an air gauge the tolerance band has to be fairly narrow. Rather than just having each air channel go directly to a readout they each went into a computer that could run some math on the inputs, something like this: Epic CAG from Edmunds Gages

The feature was short and the feature to be measured was in the same plane as the datum. One or two air channels ran on the datum feature and the other two ran on the surface being checked. I'll ask a former co-worker if the remember any of the specifics, but not promises as it's been a while.
 
I wasn't able to find anything out on the original, but another former co-worker advised that they've seen Jenoptik air gauging that does what you're after. Unfortunately I don't have an Applications contact to offer.
 








 
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