Hey folks.

I purchased a set of Shars micrometers with separate insturments from 1 to 6.

I have been practicing with them to get a feel for them by measuring an item with the micrometer and then with a pair of digital calipers that I have.

I was getting a difference of .005 +/_ and I tried measuring the 4 standard that came with the set and ended up with the same error.

After a bit of head scratching I found the little hole on the back and found that the tiny spanner wrench fit it and I was able to zero the mic to the standard.

A couple of questions: Do these micrometers need to be checked every time before use and what factor does temperature have in doing measurements?

Thanks,

Brad
 
if they are new to you and just started using them i would check each time for a while to see if they hold zero. after you get a feel for them and they hold zero then i would just check once a while unless you are working on something that you need to be on the mark. when i use mine alot i check often when you need to be in the .001 range,keep them some place were they do not get knocked around and in a case will help.
 
Check both ends of the scale as well. Use 4" and 5" standards to check 4-5 mic. Expect max .001" variation over entire range. Clean faces well.
 
It really depends on how they are used and stored. Any quality precision instrument deserves to be handled and used correctly and with care.
If a micrometer is tightened too tight or is dropped, even lightly dropped, it should be checked for accuracy.
 
seems like any of the digital micrometers I have ever used needed to be zeroed pretty regularly. Especially if they were shut off and turned back on. Pretty much just got in the habbit of checking it to see if it was zeroed everytime I turned it on. Not so much cause you had to zero it every time, but because of the times it did need zeroed.
 
It depends on how rough they are treated and how much they are used.
I'm missing the 2" standard on my 2-3 mic so when I was measuring up a 3 cylinder Ford crank a while back I borrowed a 2" standard from a friend of mine. It hasn't been checked for at least 5 years and was still on.
If you have the ratchets on your mics use that to get a more accurate measure.
It takes many years of practice to tighten one by feel.
Temp does make a difference but it is so slight that most of us could never measure the difference.
However, I wouldn't expect a measurement I took with the temp at -20º to be the same as if I took it at +80º
 
(quoted from post at 22:37:30 09/23/14) Hey folks.

I purchased a set of Shars micrometers with separate insturments from 1 to 6.

I have been practicing with them to get a feel for them by measuring an item with the micrometer and then with a pair of digital calipers that I have.

I was getting a difference of .005 +/_ and I tried measuring the 4 standard that came with the set and ended up with the same error.

After a bit of head scratching I found the little hole on the back and found that the tiny spanner wrench fit it and I was able to zero the mic to the standard.

A couple of questions: Do these micrometers need to be checked every time before use and what factor does temperature have in doing measurements?

Thanks,

Brad

The way I was instructed was that one guy should be doing the measuring and that his set of mics was HIS set, not anyone elses. When you set the mic to the standard it's set for the way you tighten it up, not the way I do, so it will differ between people. My dad probably would smack me in the head if he ever saw me "spin a mic in" like so many noobies do. You come up slow and easy and so the faces just kiss the item. If there's a ratchet you still need to go slow and easy. Get the Starrets book for apprentices machinists if it's still offered. It tells you why you do things slow and easy and just kiss the object you are measuring. You can introduce variations well over .001 with a 1" mic just by the way you tighten it up.
 
Hello Brad Buchanan,

If you are measuring in the 10k you should calibrate the mike every time you use it.
Temperature will always be a factor.

Guido.
 
Thanks for all the help, guys.

I am working on the rebuild on the Ford 4500 and today I checked the crankshaft for straightness with my dial indicator.

I am having the block sleeved and new cam bearings installed.

I will update when I get further along on the project.

Thanks again,

Brad
 
Never hurts to check them first. Very encouraging that you have developed the correct feel for them and you are measuring consistently.
 

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