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which neck wall thickness measuring tool?

I used to use a tubing micrometer, but when I bought my RCBS Chargemaster on sale, the price was shy of the $300 required for the rebate. So I bought the RCBS Case Master Concentricity Gaging Tool to up the total value of my purchase. As it turns out, it does a good job measuring neck thickness and now I use it more often than my tubing micrometer. Works well for bullet run out as well.

The precision might not be quite enough for some shooters, but it's good enough for my purposes. The dial indicator can be read to parts of a thou, maybe .00033 or .00025 if you have a good imagination. It costs about $106 if you shop around plus a rebate of (I think) ten bucks.
 
Mitutoyo tube mic. Used for years. Always accurate and repeatable. As with any hand held measuring device technique and "feel" are everything.
 
Forster or NECO concentricity tools with a mandrel and dial indicator for me. I use the Forster the most because its easier to set up than the NECO. More accurate than my tubing mic.
 
You can take any good tubing mic like the Mitutoyo and easily make a depth stop for it. I took a short length of dowel, drilled the right size hole in the middle, used a razor scraper blade and a small mallet to split the cylinder in two through the middle of the hole, then glued it back together around the anvil shaft. Finally I ground away the "bite" to make clearance for the cylindrical spindle. I can slide the stop up and down a bit on the shaft, but I leave it bottomed out, or slide in circlip shaped shims (made from plastic tab-style bread bag closures) underneath it to raise it .

CIMG6621-2.jpg
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Has anyone ever compared a cheap digital to a good Mitutoyo, Starett or similar? I have a Mituyoto Tube and a grizzley stand. I wish it was a little easier to read the smaller hashes. Had to get a retired engineer to show me how to use it.
 
I measure my neck thickness with a mitutoyo anvil mic 395-372 it measures .01225" but when i check it on my Sinclair case neck sorting stand with a digital Starret gauge or an SPI dial gauge these 2 gauges measure it at .0145" . I'm measuring it at the same point on the neck. Any reason why these 2 gauges measure it differently to the mitutoyo?
 
I bought a Mitutoyo set of digital calipers and a digital micrometer of there's. When I look at their tube micrometer, I think it was about three or 4 times the price of the digital micrometer if you wanted a digital one. In reading up on these (As I am not very experienced) many seem to think that it is hard to read the old fashion analogs ones, so I ended up buying the Sinclair. Probably in the middle on price and nicely mounted on a base/stand. I even was sent pictures of a desired modification recommended to make for it, which I have yet to do.

Bob
 
rkittine said:
I bought a Mitutoyo set of digital calipers and a digital micrometer of there's. When I look at their tube micrometer, I think it was about three or 4 times the price of the digital micrometer if you wanted a digital one. In reading up on these (As I am not very experienced) many seem to think that it is hard to read the old fashion analogs ones, so I ended up buying the Sinclair. Probably in the middle on price and nicely mounted on a base/stand. I even was sent pictures of a desired modification recommended to make for it, which I have yet to do.

Bob
Click to expand...

What is the desired modification your talking about rkittine?
 
michaeljp65 said:
I measure my neck thickness with a mitutoyo anvil mic 395-372 it measures .01225" but when i check it on my Sinclair case neck sorting stand with a digital Starret gauge or an SPI dial gauge these 2 gauges measure it at .0145" . I'm measuring it at the same point on the neck. Any reason why these 2 gauges measure it differently to the mitutoyo?
Click to expand...

How do you assure they all measure at the same distance from the case mouth ? Even if they all have depth stops (the Mitutoyo doesn't unless you added one) how do you adjust and determine the depth stops all coincide? (This only matters much if the necks have never been turned, so the neck walls still taper significantly thinner towards the case mouth.)
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I am trying to find the photos that were sent to me, but basically it was a way to hold the cases and free up a hand.

Bob
 
brians356 said:
How do you assure they all measure at the same distance from the case mouth ? Even if they all have depth stops (the Mitutoyo doesn't unless you added one) how do you adjust and determine the depth stops all coincide? (This only matters much if the necks have never been turned, so the neck walls still taper significantly thinner towards the case mouth.)
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Click to expand...


Gday Brian,
My necks have been turned.
How do you assure they all measure at the same distance from the case mouth ? I put a small felt tip pen mark about 3mm from case mouth. Thats about halfway between the sizing bushing.
Even if they all have depth stops (the Mitutoyo doesn't unless you added one) how do you adjust and determine the depth stops all coincide? By the felt tip pen mark. The mitutoyo measuring tube, the one you screw in and out has a full face, 5mm about. The 2 dial gauges have rounded shaft ends that contact the case.

Ive read on here that blokes are within .0001 or better accuracy all the way around on each turned case. I cant get anywhere near that, and im trying to work out how they can be so accurate with their turning. Ive tried K&M neck turner and a 21st century lathe and by hand held. I only get between .0001.5-.0005. Ive never had a Lapua case (thats all i use) that was an even thickness all the way around.
 
michaeljp65 said:
Ive read on here that blokes are within .0001 or better accuracy all the way around on each turned case. I cant get anywhere near that, and im trying to work out how they can be so accurate with their turning. Ive tried K&M neck turner and a 21st century lathe and by hand held. I only get between .0001.5-.0005. Ive never had a Lapua case (thats all i use) that was an even thickness all the way around.
Click to expand...

Since your necks are turned, there is less need for a precise depth stop. Still, it's something you should have on the Mitutoyo, to make sure the measurement is always the same distance from the case mouth (assuming the necks are all the same length) especially with unturned necks arebeing assessed. Take a look at mine a few posts back in this thread.

WRT variations of .0001", I'd have to measure that myself to believe it, if a typical turning tool on a mandrel was used. However, if the mandrel was precisely enough fitted to the neck ID, using custom made expander and turning mandrels, it might be attainable. I'm using using Sinclair expanders, and the turning mandrels that fit my Hornady turner, so the fit is not particularly snug, and I can get .0003" variance without any trouble at all. Still, getting to .0001" would be a neat trick.

I don't think you need anything like .0001" and I challenge anyone to prove it makes a difference on the targets vs .0003". (Ok, proving it is setting the bar impossibly high, but someone will swear it does.) But you should be able to get under .0005" more consistently, based on my initial results using the Hornady tool and sub-optimal mandrel fit.
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brians356 said:
Since your necks are turned, there is less need for a precise depth stop. Still, it's something you should have on the Mitutoyo, to make sure the measurement is always the same distance from the case mouth (assuming the necks are all the same length) especially with unturned necks arebeing assessed. Take a look at mine a few posts back in this thread.

WRT variations of .0001", I'd have to measure that myself to believe it, if a typical turning tool on a mandrel was used. However, if the mandrel was precisely enough fitted to the neck ID, using custom made expander and turning mandrels, it might be attainable. I'm using using Sinclair expanders, and the turning mandrels that fit my Hornady turner, so the fit is not particularly snug, and I can get .0003" variance without any trouble at all. Still, getting to .0001" would be a neat trick.

I don't think you need anything like .0001" and I challenge anyone to prove it makes a difference on the targets vs .0003". (Ok, proving it is setting the bar impossibly high, but someone will swear it does.) But you should be able to get under .0005" more consistently, based on my initial results using the Hornady tool and sub-optimal mandrel fit.
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Click to expand...


Today i made a depth stop for my Sinclair micrometer like i saw either in this thread or another with a bent piece of aluminium with a notch cut out around the anvil. My Mitutoyo is a digital one and there is not much room under the anvil as in your photo, maybe 3mm or so. But i'll work something out.

Cheers
 
michaeljp65 said:
Today i made a depth stop for my Sinclair micrometer like i saw either in this thread or another with a bent piece of aluminium with a notch cut out around the anvil. My Mitutoyo is a digital one and there is not much room under the anvil as in your photo, maybe 3mm or so. But i'll work something out.
Click to expand...

Here's what I made for shimming up the wooden stop. Start with a plastic bread bag closure, drill a hole the size of the anvil shaft, then notch and shape with an Xacto so it is a force fit onto the shaft, it flexes enough, and stays in place until you yank it off.

CIMG6705.jpg
CIMG6707.jpg

You might fit two or three of these in that 3mm space, as required.
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