Anyone using a neck wall gage like this?

[Brians356]

Anyone using a neck wall uniformity gage like this one?

http://www.ebay.com/itm/201563155121?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Obviously there is no stop for the case mouth, which would be fairly easy to make out of tubing, but still is a deficiency of the design. If the necks have already been turned, not as critical.

What I wonder about is the ability of the indicator stem to hold the neck firmly enough against the mandrel. Dial indicators I have used have a very light stem spring force, and I wonder if the neck will float a bit here (depending on the mandrel fit.) If so, the operator will have to press the case "down" against the mandrel while turning it, which is a bit awkward.
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[hpshooter]

The one I have seen like this in the past had a pin like a de-capping pin that located the case via the flash hole and an internal neck bushing.

 

[jlow]

There are two types of neck wall gauge. The type that is used to profile and cull cases which is like the one the OP is asking about, and the other type which is a ball micrometer type which is used to more accurately measure wall thickness after neck turning. Neither replace the other but the difference is one is made to measure thousand difference, and the other then thousands difference.

 

[Brians356]

There are two types of neck wall gauge. The type that is used to profile and cull cases which is like the one the OP is asking about, and the other type which is a ball micrometer type which is used to more accurately measure wall thickness after neck turning. Neither replace the other but the difference is one is made to measure thousand difference, and the other then thousands difference.

I have a Mitutoyo .0001" ball mic, and use it.

The ~$80 SPI #24-303-0 dial indicator shown with the fixture discussed also reads to .0001". FWIW.
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[JohnKielly]

Seems like the user could generate more than a few thousandths error manipulating the case on the mandrel.

 

[jlow]

That's exactly correct. Just because the dial allows you to read 1 ten thousands does not mean that the setup is capable of doing so. I use a Redding and the problem with all of these is the mandrel that you rotate the case in has to be significantly smaller than the neck 1) because if it is exactly the same size, there would be too much drag, and 2) it would not fit too many necks. The fact that it does not fit exactly means you will get lots of noise in your reads.

 

[ireload2]

Not if you have any skill at all. After measuring the same case about 20 times you should have enough practice to be fairly accurate.

Seems like the user could generate more than a few thousandths error manipulating the case on the mandrel.

 

[Brians356]

I think I see the light. For almost the same price the Sinclair Case Neck Sorting Tool has one critical extra feature (the pilot/neck stop) plus the alignment rod. And it has a larger base and appears more stable. But it will still suffer from the same accuracy and repeatability limitations compares to a tubing mic-based system.

Sinclair's demo video is careful not to focus on the dial face to demo repeatability. Since Sinclair also sells their mic-based Case Neck Micrometer fixture, they tacitly imply that the Sorting Tool is for rough sorting, not accurate sorting measurements.

Thanks for the comments. I'm satisfied I have a handle on the limitations of this type of fixture.
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[jlow]

It is indeed a sorting tool like the Redding, they work good as long as the expectations are reasonable which yours are.

 

[ridgeway]

Seems like the user could generate more than a few thousandths error manipulating the case on the mandrel.

Same holds true for a mic. Guys like to measure like they are tightening a c-clamp, lol