In-House Calibration - Digital Micrometer found Out of Calibration

T

tknchancs

We calibrate/verify, in-house against Jo-blocks calibrated to a known standard, the micrometers and calipers used for Production and Inspection. I recently came across a digital micrometer that is off .005 on the barrel and the screen is not working (probably dead battery). Can we make the necessary adjustments in-house or should we send it out to a calibration service?
 

Stijloor

Leader
Super Moderator
Re: In-house calibration

Welcome to The Cove Forums! :bigwave: :bigwave:

If your technician has the required competencies to make the necessary repairs and adjustments, yes you can do this in-house.

Stijloor.
 

Big Jim

Admin
Re: In-house calibration

We calibrate/verify, in-house against Jo-blocks calibrated to a known standard, the micrometers and calipers used for Production and Inspection. I recently came across a digital micrometer that is off .005 on the barrel and the screen is not working (probably dead battery). Can we make the necessary adjustments in-house or should we send it out to a calibration service?

The fact that you are asking tells me you probably should not. Those skills are not hard to learn, but if you don't know them the consequences can be disastrous.
 

BradM

Leader
Admin
Re: In-house calibration

We calibrate/verify, in-house against Jo-blocks calibrated to a known standard, the micrometers and calipers used for Production and Inspection. I recently came across a digital micrometer that is off .005 on the barrel and the screen is not working (probably dead battery). Can we make the necessary adjustments in-house or should we send it out to a calibration service?

Hello there!:bigwave: In other words, howdy, from a fellow Texan!:bigwave::D

It depends on the reason the instrument is out of calibration. The parallelism may be off on the jaws. If so, it may be worth it to trash the instrument and replace them.

1. Assure the problem is not with the standard or the calibrator.
2. Try to determine what the problem is with the instrument. Most dimensional instruments (Mitutoyo, Starrett, etc.) don't usually get off, if they have demonstrated repeatability. But it does happens:D.

Just write up the issue, assure that no significant impact has occurred, replace the instrument, and move on.:D
 

AndyN

Moved On
Re: In-house calibration

I agree with Jim!

When you say it's off by an amount, it's useful/necessary to know where it's off also. Is it only at zero? Or does a (similar) error occur along the range? Calibration should check for that, not just at zero!
 
B

brahmaiah

We calibrate/verify, in-house against Jo-blocks calibrated to a known standard, the micrometers and calipers used for Production and Inspection. I recently came across a digital micrometer that is off .005 on the barrel and the screen is not working (probably dead battery). Can we make the necessary adjustments in-house or should we send it out to a calibration service?
You have to send it for recalibration after replacing the battery cell.
And secondly you have to investigate if the defective instrument was used to measure any products.If so required corrective action should be taken without delay.
V.J.Brahmaiah
 
B

brobinson

Throw away micrometers for parallelism error?

Wow...Must have an unlimited budget or are buying the el cheapos made of poor quailty in ZaZa Land.

There are several factors that could contribte to the gague being off .005" Some possibilities that I would consider:
1) Possibly a burr on the spindle or anvil face.
2) Parallelism of the two faces could be off.
3) The flatness of the anvil or spindle face could be of error.
4) Zero setting is off.
5) Standard is not qualified to nominal dimension.

These checks can be performed by trained technicians as stated earlier. The adjustment of zero can easily be done. If parallelism is bad, the gauge should be sent out to a reputable calibration house to have the faces lapped parallel and the thimble repositioned to compensate for the change.

Being off .005" is rather significant.

There are just too many variables to consider when there is an error this large. Simple adjustments of a few tenths- to a few thousandths of an inch can be made on the barrel. Over this and the zero line becomes too far out of position to easily read the gauge for future inspections. If an adjustment is .005" is required after all other possibilites are eliminated, I sugges that the thimble be repositions on the spindle and leave the barrel adjustment for the smaller increments.
 
B

brahmaiah

The methods suggested by Brobinson are ok.But if the mike is very old there is a possibility of irrepairable wear on anvils and threads.In such a situation the best thing to do is to scrap the mike.
V.J.Brahmaiah
 
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BradM

Leader
Admin
Throw away micrometers for parallelism error?

Wow...Must have an unlimited budget or are buying the el cheapos made of poor qualtiy in ZaZa Land.
:D

How much did you spend filling out all the paperwork, shipping it off, having the parallelism repaired, getting it back in, and then increasing frequency intervals to assure corrective action? :D Probably about as much as I spent buying a new one.:)

You have some really good suggestions in your post for detection.:yes: All I'm saying is that if there is a failure, sometimes one should know when to Hold, and know when to Fold.:D All that is dependent on the instrument, the nature of the failure, and what level of service they will give when they repair. Too, sometimes getting a decent calibration certificate after a repair costs extra.
 
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