OD Mic Zero Adjustment

[blue45colt]

I'm not sure if this is the correct place to post this, if not please direct me.

I have a Starrett 0-1" OD mic that is a little out of zero adjustment, and I'm not sure how to make the required adjustment to re-zero it.
Does anyone know how to do this, and if so could you share this information?

Thanks

[grumpy one]

On my Mitutoyo mics I use the little C-wrench supplied and rotate the graduated inner barrel slightly so that the zero lines up. I've also had an off-brand mic on which you could loosen and rotate the outer barrel on the screw. I've never needed to adjust any of my Starretts so I don't recall how you do it. (I use Mitutoyos with carbide surfaces in high-usage sizes, and Starretts with steel surfaces in low-usage sizes).

[Morgan Astorbilt]

Unscrew the outer barrel, and you'll see a circular nut at the end of the inner barrel. This is your adjustment. You'll need a small spanner to loosen it, and turn the required amount.
Morgan

[HotGuns]

You need to use a standard to get it right. That being a 1.0000 rod about 1/4" dia. that is made as a standard, thus very accurate.

[ANeat]

With a 0-1 you use "0" as the standard

[redneckdan]

on my starret, you use the spanner to rotate the inner barrel. I use 0 to set and double check on a .25 .5 and .75 gauge block (I'm OCD with measuring tools[smilie=1:).

[blue45colt]

The nut on the end of the inner barrel is threaded onto what looks like a collet. Is this the adjustment nut you are talking about?
This collet type joint almost looks like it is there to provide adjustment for thread clearance takeup to minimize "endshake" in the threads.

This mic also has a place for a spanner wrench on the inner barrel more in line of what red neck dan described.

Thanks to all for the input.

[Morgan Astorbilt]

Almost all the time, being "Out of zero", as you described it, has the mark going past zero. This is due to backlash in the threads, and the round nut with the notches for a spanner, is used to take this up, bringing it back to zero. If your mike has a friction ratchet (a small knurled knob at the end of the barrel) always use this to take measurements, it will help you take accurate measurements, without having to develop the "feel", and will protect the threads.
Morgan

[HotGuns]

With a 0-1 you use "0" as the standard

Yep that'll work...for small end.
To properly check to see if its linear, you do both the small end and the large end.

If its ever been dropped, and the threads are pulled or distorted on it somewhat, it may be good at the small end and off somewhat on the large end or vice versa...but if you dont check both ends, you wont know that.

While it may not matter so a much on a home project, it may on something else.

That's why the 1" standard is supplied with Mic sets.,,otherwise the standards would start at 2" instead of 1".

[Morgan Astorbilt]

Yep that'll work...for small end.
To properly check to see if its linear, you do both the small end and the large end.

If its ever been dropped, and the threads are pulled or distorted on it somewhat, it may be good at the small end and off somewhat on the large end or vice versa...but if you dont check both ends, you wont know that.

While it may not matter so a much on a home project, it may on something else.

That's why the 1" standard is supplied with Mic sets.,,otherwise the standards would start at 2" instead of 1".

Hate to disagree, but in a mike set, the 1" standard is supplied for checking the 1"-2" mike. All the other standards, only go up to the minimum setting of the largest mike, not the max.(ex:, a 5"-6" mike will use a 5" standard)
A single 1"-2" mike is only supplied with the 1" standard, and a 0-1" mike is never supplied with one, not even the best tool room mikes reading in tenths.
Morgan

[HotGuns]

A single 1"-2" mike is only supplied with the 1" standard, and a 0-1" mike is never supplied with one, not even the best tool room mikes reading in tenths.

Gee thats funny. Every single cased 0-1" mic I use at work has a 1 inch standard laying right there beside it.
When I went though tool and die apprentiship 30 years ago, I was taught to always check both ends. This was demonstrated to us by a Mic that showed to be zero when fully closed and was .012 off when checked at one inch.

I guess I was taught wrongly. :confused:

My bad.:veryconfu

FWIW, the Mitutoyo 0-6 inch set that I used everyday at work reads in tenths of a thousanth.
Also,the 6" to 12" is supplied with standards as well.

Are you telling me that you only need to check the top end?
That makes me wonder why the guys in the Met Lab go though so much trouble when certifiying calibaration by checking a Mic through its whole range. Seems to me like they would cull a lot less if they just checked one end of the measurment.

[R.M.]

Well, I'm going to say that Morgan is not wrong. I won't say that HotGuns is wrong, it's just that I've been a Tool & Die Maker for 35 years, and have never seen a standard in with a 0-1 mic. It sure isn't a bad thing to check both ends, and if you have a 1-2, then you have a 1" standard to check the 0-1 should you feel a need.

Just what I've observed.
R.M.

[Morgan Astorbilt]

Hotguns, When you have your mikes calibrated, they do it through the whole range. That's what you're paying for. They also don't hold the mikes in their hands, so they don't expand from the heat, and test them after being normalized at room temperature, which is noted in the calibration report. This is all way out of what is SOP in tool and die, and tool room work. The only measuring item which I don't hold in such a way as to transfer heat from my hands, is the precision levels I use for installing and setting up machinery. They have grip areas isolated from the metal frames for this purpose. I've been working in tenths for most of my adult life, going to a special high school for this, and then having had a small job shop specializing in prototype scientific instruments, to augment my cop's pay. I guess we'll just have to agree to disagree.
Morgan

[HotGuns]

Morgan..
I've got to have my Mic's calibrated every six months...or when it doubt I just bring it over to the Met lab. These guys are in an environmentally controlled 72 degree lab, they wear the lab coats and wear the plastic gloves to touch everything. The machine that they use is hard to describe, but it measures in millionths. It sits on a granite surface plate and costs a small fortune.
The environment that I work in has specific procedures to work with. Something as simple as using a out of cal instrument or even one that the cal.sticker falls off of has caused many embarrassing and often costly delays as well as some pretty hefty fines slapped on the company for non-compliance... and that usually makes the 6 o'clock news around here.

I'll agree with the fact that its not SOP in tool and die,or tool room work. Fact of the matter is, some of what we are mandated to do is way over board, but that is the way it is.
Really, I don't see anything to disagree with. I never saw a one inch standard issued in the same case as a 1 inch mike till I started working here 25 years ago either, but they are here and I use them everyday. The fact that most other people have never seen one doesn't surprise me in the least.

I occasionally am called upon to teach Micrometer basics to vendors and mechanics. This is a one day class that teaches them the basics and gives them a little practice at something they don't often do. Although our Mic's can read to tenths, expecting someone that doesn't do it for a living to get good consistent readings is a bit unrealistic. As I'm sure you are aware, the difference between two people that do it for a living can easily be a couple of tenths.

Anyhow...
That sounds like a great job you have there. Sounds like a great way to augment your retirement. I've thought about doing something like that when I retire, but at the rate I'm going working on guns, that may take all the time Ive got when I get there...still have a few years to go if the Lord don't come and the creeks don't rise. BTW...Im a part time Deputy Sheriff too. I love doing it, but couldnt afford to do it full time. At the moment Im making about 3 times the salary of the Sheriff. Cop pay in the south is pitiful.