Ball Micrometer

A

abintx

Guest
Looking for a Ball Micrometer for measuring case neck thickness after turning. Does anyone have a favorite?
 
I think what you need is a pin mic. Most ball mics have a .250 ball; whould be too big for smaller calibers.
 
Lyman makes one that is inexpensive.

What you actually want is a tubing micrometer, Starrett makes the best.
 
I used the word "ball" because of this: http://www.midwayusa.com/product/544254/rcbs-vernier-ball-micrometer-1 Anyway, this is the type I'm looking for.

Does any mic have a "stop depth adjustment" so you can measure at the same spot as you rotate the neck for comparing a prior reading on the same neck, or perhaps a very short post? [I've seen pieces of tape used for this purpose which seems a little crude given the cost of some of these mics.]

P.S. Just passed this idea on to John Perkins at 21st Century to see if he can come up with an adjustable sleeve on a cylindrical post with the ball still on top. He's great at making a tool better than the original.
 
I have a cheap RBCS set that works just fine. I think i bought the set for 40 bucks?? Look on ebay and see what you can find. Lee
 
case neck thickness measurement

Abintx -

What DeltaBravo said.

The device is a bit " technique-weighted " ( at least it is for me ), but works well once you become accustomed to its operation.


With regards,
.357Mag
 
For something as important as measuring neck thickness, why mess with anything else but a Mitutoya ? Spend the money once.
 
K&M offers a Mitutoyo with a stem ground at an angle for clearance if you want to measure close to the neck/shoulder junction. Its pretty nice and accurate down to .0001". I had a decently made import that was ut as accurate as the Mitutoyo. Moral: get the best you can afford that can read down to tenths.
 
Mitutoyo

I have a digital mitutoyo that has an optional stop depth adjuster. Feels nice in the hands and accurate.
Andy.
 
JerrySharrett said:
Turn the neck, seat your bullet then measure over that finished assembly. That is where the rubber meets the road.
Click to expand...

Jerry,

That's what Jackie Schmidt taught me and that's what I've been doing for years.

I thought I'd give the "check the neck thickness" method a try to satisfy my curiosity once and for all.
 
Measure bullet to .0001, measure neck thickness to .0001 after lightly polishing with 0000, seat bullet, measure OD over largest diameter of bullet, check each case neck after turning to .0001 (I usually only work with small batches.) The last step if a hold over from when I did not have a carbide mandrel and brassing on the mandrel, directly under the cutter could jump up and bite you.
 
Bump

abintx said:
Does any mic have a "stop depth adjustment" so you can measure at the same spot as you rotate the neck for comparing a prior reading on the same neck, or perhaps a very short post? [I've seen pieces of tape used for this purpose which seems a little crude given the cost of some of these mics.]

P.S. Just passed this idea on to John Perkins at 21st Century to see if he can come up with an adjustable sleeve on a cylindrical post with the ball still on top. He's great at making a tool better than the original.
Click to expand...

Did you ever find a ready made depth stop solution for using the ball micrometer?

(Advising someone to just turn the case necks, then measure loaded rounds' necks, misses the common use for a ball mic - to determine what you have in hand before neck turning. A depth stop is an obvious need since most factory case neck walls are progressively thinner between shoulder junction and case mouth.)
 
Interesting comment on tightening the thimble. I once caught a guy using a Starrett mic to clamp
two pieces of sheet metal together. Needless to say, he didn't have to buy his own tools.
 
Could it be

that Butch is being a little "tongue in cheek"? I have noticed , as I'm sure most of you do, that I can vary the reading depending on how much pressure I put on the thimble. Thus it can be easy to "get the reading you want".
 
I have some neck turners made by george ulrich that has an indicator built in. Using a cutter made by a master toolmaker makes life easy- cuts look like a polished mirror
 
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