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abintx
09-24-2013, 11:00 AM
Looking for a Ball Micrometer for measuring case neck thickness after turning. Does anyone have a favorite?

Jkob
09-24-2013, 11:24 AM
I think what you need is a pin mic. Most ball mics have a .250 ball; whould be too big for smaller calibers.

kansasvet
09-24-2013, 11:34 AM
Lyman makes one that is inexpensive.

What you actually want is a tubing micrometer, Starrett makes the best.

abintx
09-24-2013, 12:57 PM
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.

DeltaBravo
09-24-2013, 05:18 PM
If you can live with 0.0005 inch accuracy, this works fairly well:

http://www.sinclairintl.com/reloading-equipment/measuring-tools/micrometers/insize-digital-thickness-gage-prod36561.aspx

Dennis

skeetlee
09-24-2013, 09:27 PM
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

.357Mag
09-24-2013, 10:10 PM
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

Joe Maisto
09-24-2013, 10:21 PM
For something as important as measuring neck thickness, why mess with anything else but a Mitutoya ? Spend the money once.

DSM
09-24-2013, 10:34 PM
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.

Andy Cross
09-25-2013, 12:12 AM
I have a digital mitutoyo that has an optional stop depth adjuster. Feels nice in the hands and accurate.
Andy.

JerrySharrett
09-25-2013, 06:20 AM
Turn the neck, seat your bullet then measure over that finished assembly. That is where the rubber meats the road.

abintx
09-25-2013, 11:06 AM
Turn the neck, seat your bullet then measure over that finished assembly. That is where the rubber meets the road.

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.

Bill Scheider
09-25-2013, 11:28 AM
Turn the neck, seat your bullet then measure over that finished assembly. That is where the rubber meats the road.

Agree 100% with Jerry, above.

We have a Mitutoyo Ball Mic., but find the neck measurement with loaded bullet much more accurate and trouble-free.

Boyd Allen
09-25-2013, 02:40 PM
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.

Brian Adams
08-01-2014, 05:57 PM
Bump


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.

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.)

Butch Lambert
08-01-2014, 08:21 PM
If I turn the thimble on mine tight enough I can get the measurement that I want.

kansasvet
08-01-2014, 11:48 PM
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.

John Kielly
08-02-2014, 02:05 AM
Fancy not knowing when to use Verniers.

adamsgt
08-02-2014, 11:40 AM
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".

Dusty Stevens
08-03-2014, 12:06 AM
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

JRB
08-03-2014, 07:53 AM
I have a digital mitutoyo that has an optional stop depth adjuster. Feels nice in the hands and accurate.
Andy.

Andy,
Where did you get the stop depth adjuster from?
Jim

Butch Lambert
08-03-2014, 12:25 PM
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".


You are correct Jerry.

kansasvet
08-03-2014, 08:37 PM
I realized Butch was joking. I have seen micrometers abused in about every possible way, the use
as a clamp was one of the worst. I have also seen people force a preset mic over a shaft, 4 to 8 in dia.
to prove the length of the shaft was totally true. People never cease to amaze me in their abuse of fine
tools.

abintx
08-05-2014, 09:55 AM
Bump



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.)

No. Continued my method of measuring the OD of the loaded round. Keeping it simple. :)

Lee Martin
08-05-2014, 09:58 AM
I use a ball micrometer to assess factory thickness....it gives me a starting point for lathing the necks. But like others, I rely on the loaded O.D. relative to the chamber.

-Lee
www.singleactions.com

Andy Cross
08-05-2014, 06:27 PM
Andy,
Where did you get the stop depth adjuster from?
Jim

Just noticed this post. Slack old me.

I was in Yokahama in 2010. Saw it in a mitutoyo dealership. Had to get it.
Andy.

max.burgess
08-20-2014, 04:44 AM
Where is the correct place to measure a case ? I noticed they are thicker as you move deeper into the case.

Lee Martin
08-20-2014, 09:42 AM
I measure a few points on the neck, starting midway down:

http://www.singleactions.com/images/Tube_Micrometer.jpg

-Lee
www.singleactions.com

Wilbur
08-20-2014, 01:18 PM
I guess I've forgotten - as I have so many things. Catch me up please Sir. Why would I care what the original neck measured if my intent was to turn the neck true...and to fit an undersized chamber?

Having a "depth stop" is really important when you're measuring bullet jacket wall thickness. You can have one made if you need one. Frankly, there was a "lot" of bullet jackets that varied quite a bit and I sent them back. Turns out that they were record setting jackets! No, I wasn't wrong in my measurement. The jackets were terribly poor (by the standard of the day) but made EXCELLENT bullets. Go figure!

Brian Adams
08-21-2014, 02:42 PM
Having a "depth stop" is really important when you're measuring bullet jacket wall thickness. You can have one made if you need one.

I finally made my own, out of a short section of hardwood dowel. Made the plug the height I wanted, drilled a 5/32" hole in the middle (happened to fit the shaft where it would go perfectly) then I used an Xacto knife and a small mallet, rapping on the back of the blade, to split it along the grain through the hole, and glued the two halves back together, around the shaft, using thin super glue. It's permanently in place, but will be easy to split apart and remove some day. I can slide it up and down to change the height, and I made a couple of shims out of plastic bread bag clips to wedge under it.

Brian Adams
08-21-2014, 04:25 PM
Catch me up please Sir. Why would I care what the original neck measured if my intent was to turn the neck true...and to fit an undersized chamber?


Sorry, missed your question until now:

I don't turn necks, I sort factory brass and cull out those with a lot of neck thickness variation.

Un-turned necks seem to have walls the get progressively thicker towards the shoulder, so a depth stop is obviously required in that case.

But a stop I think is handy even with turned necks, it supports the case and allows you to concentrate more on operating the mic and less on holding the case.

mario f
08-21-2014, 05:08 PM
I use this

Brian Adams
08-21-2014, 05:17 PM
I use this

Photo a bit indistinct, I cannot see a depth stop. Can you explain how it works?

Frank B
08-23-2014, 12:35 AM
If I turn the thimble on mine tight enough I can get the measurement that I want. Works for me also. Later! Frank