Questions about standards (measuring rods) for micrometers

[mmcmdl]

Also, make sure the faces of your 0-1" mic are NOT touching when you store it.

Yes , that is a no no , same with calipers .

 

[Boswell]

Yes , that is a no no , same with calipers

ooo I did not know that. thanks for the tip.

 

[erikmannie]

Yes , that is a no no , same with calipers .

Yes, I always leave them open a little.

So how often are you guys breaking out your micrometer standards?

How often are you guys checking the zeroes on the outside micrometers larger than 1” (or 25mm)?

 

[mmcmdl]

Never . No need to .

So how often are you guys breaking out your micrometer standards?

How often are you guys checking the zeroes on your outside micrometers?

 

[erikmannie]

...2) I always clean the mic faces with Kim Wipes and gently close them to make sure the mic is zeroed before use. I could probably dispense with this because the mic always reads zero.
3) Mic standards (rods) are not used often so if you buy good ones used, they will probably be okay...

So we all know how to do this with 0-1” mike, but if it is 1-2”, 25-50mm, and up then my understanding is that the purpose of the measuring rod is to “make sure the mike is zeroed before use” as mentioned in (2) above.

For a larger micrometer, I would not know of a way to make sure the mike is zeroed before use without using a standard. I have always thought that one needed a standard to check the zero on a larger mike.

 

[rwm]

I didn't even know you could have 4 digits after a decimal point?
R

 

[erikmannie]

I didn't even know you could have 4 digits after a decimal point?
R

Not for the metric folks. Not too many people posting about .0001mm as each one of these units is 39.37 millionths of an inch.

Everybody here probably knows this, but I wondered what metric people machined to (because I was only hearing about thousandths). Someone on here said that they machine to .1mm for most stuff, and to .01mm for really precise stuff. So this is basically equivalent to machining to .004” for most stuff, and down to .0004” for really precise stuff. This makes sense.

 

[mmcmdl]

For a larger micrometer, I would not know of a way to make sure the mike is zeroed before use without using a standard. I have always thought that one needed a standard to check the zero on a larger mike.

Yes , you do need a standard or gage blocks to initially set larger mics to zero . Then check them every so often .

 

[erikmannie]

Yes , you do need a standard or gage blocks to initially set larger mics to zero . Then check them every so often .

Thank you for your prompt reply. I was very curious about that. I had been doing it every day, but I will loosen up a bit and have more faith in the workmanship of the equipment.

The Starretts are fine, BUT the first micrometers that I got were all Shars, and they won’t even return to zero after measuring a standard. So I got off to a rocky start as far as having faith in the metrology equipment.

 

[MontanaLon]

I agree with Dave. Also, make sure the faces of your 0-1" mic are NOT touching when you store it.

And it goes without saying if your faces ever touch on a 1-2" or larger micrometer, any measurements are to be viewed with suspicion.

Really all the standards that come with the mics do is give you a zero point. They are pretty accurate and you can usually prove it to yourself by starting with your 0-1" and zero it. Then open it up and put the 1-2" standard in which will measure 1". I have found even the cheap harbor freight standards are accurate below 0.0001. You just keep repeating using the next size up standard to measure the max after checking zero.

As 3450 said, dropping them or getting them tangled up in work is really the only way to get them out of calibration. I am sure measuring abrasives would be pretty hard on them as well, but how often do we do that?