Calibrating or Verifying Metal or Steel Tape Measures

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vanputten

Re: Calibrating or Verifying Tape Measures

I think verifying or "calibrating" tape measures depends on the application. I can't imagine that we can make a sweepng statement for all organizations of the world that tape measures are always and only for reference only.

Also, I think we have given the tape measure manufacturers an incredible vote of confidence that the tapes are always correct and accurate enough no matter what the tolerance or application is.

Regards,

Dirk
 

Hershal

Metrologist-Auditor
Trusted Information Resource
Re: Calibrating or Verifying Tape Measures

Those who know me I take the position of if you have a specific need to calibrate a tape or ruler then fine, do so by sending it to an accredited calibration lab.....

But, otherwise.....its a tape, why in the world would you want it calibrated?

Hershal
 

Jen Kirley

Quality and Auditing Expert
Leader
Admin
Re: Calibrating Tape Measures

I had an AS auditor tell me that I don't have to calibrate tape measures or rulers because they are reference measuring instruments and can not be precision measuring instruments. So there was no need to have them calibrated. Is he/she wrong.
They can be labeled as "For reference only" unless they are used to measure conformity to standards, as in approval to ship. But suppose you are using the tape measure to cut pieces of sheet metal that will be fabricated to the final product? In this case calibration may not be needed unless error would be a problem. I've seen 1/16 inch or so of "stretch", usually from wear in the rivet holes holding the end on.

I've also heard reports of some tape measures being 1/4" off over their length. That could be a problem for, for example, people who do sprinkler installations.
 

Ajit Basrur

Leader
Admin
Re: Calibrating or Verifying Tape Measures

Those who know me I take the position of if you have a specific need to calibrate a tape or ruler then fine, do so by sending it to an accredited calibration lab.....

But, otherwise.....its a tape, why in the world would you want it calibrated?

Hershal

I agree 100 % with you all times. Your responses are always great :applause:
 
T

trainee

Re: Calibrating or Verifying Tape Measures

I agree 100 % with you all times. Your responses are always great :applause:

I agree with that. And I don't have a lot of experience in this, it's just...why do I need to calibrate an instrument that i use only for reference???
But, apparently that's what the auditors want...:confused:
 
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ScottK

Not out of the crisis
Leader
Super Moderator
Re: Calibrating or Verifying Tape Measures

I agree with that. And I don't have a lot of experience in this, it's just...why do I need to calibrate an instrument that i use only for reference???
But, apparently that's what the auditors want...:confused:

Then the auditor is wrong. You can contest and tell the auditor the tape is for reference only.

If the length of your product is THAT critical then you should have another, more precise, measuring system anyway.
 
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Helmut Jilling

Auditor / Consultant
Re: Calibrating Tape Measures

They can be labeled as "For reference only" unless they are used to measure conformity to standards, as in approval to ship. But suppose you are using the tape measure to cut pieces of sheet metal that will be fabricated to the final product? In this case calibration may not be needed unless error would be a problem. I've seen 1/16 inch or so of "stretch", usually from wear in the rivet holes holding the end on.

I've also heard reports of some tape measures being 1/4" off over their length. That could be a problem for, for example, people who do sprinkler installations.


Well stated. Usually, tapes are not used for important measurements, and would not need calibration/verification. However, to Hershal's comment, sometimes tapes are used for measuring/accepting large products with large tolerances - maybe 6 ft bar stock cuts. It would need to be verified that the tape is accurate and has not been damaged, wouldn't it? I have seen a lot of cases where a certified 3 or 6 ft rule is fastened to a table and the tape is verified to that from time to time. Seems suitable to me.
 
V

vanputten

Re: Calibrating or Verifying Tape Measures

Hello Hershal:

"why in the world would you want it calibrated?"

I am not sure we "calibrated" tape measures, but we sure did verify them. Here is an exaample for you.

I was the manufacturing manager for a extruded plastic sheeting and plastic bag manufacturer. All customer requirements for width and length were given with tolerances sometimes to 1/16 of an inch.

To eliminate the risk of ourt measureing devices to be the cause of nonconforming product, we purcahsed a certified metal rule. On a weekly basis, all employees had to verify their tape measure to the metal rule. Did we think the tape measures would change in their readings? No. Some tape measures did fall apart. The end peice would fall off which added uncertainty in measurements. Also, the tape measure manufacturer only guaranteed their tape measure to a tolerance greater than how we used them.

There was very little cost and time deidcated to this control. And it gave us confidence and understanding in our ability to accurately measure the bag width and length.

Forgot to add, for effectiveness and efficiency, we needed to use tape measures for inprocess inspections and montioring. We could not have used the metal rule to measure the product inprocess.

Regards,

Dirk
 

Helmut Jilling

Auditor / Consultant
Re: Calibrating or Verifying Tape Measures

I agree with that. And I don't have a lot of experience in this, it's just...why do I need to calibrate an instrument that i use only for reference???
But, apparently that's what the auditors want...:confused:

You don't, if it is only used for reference. (I don't calibrate the tape in my garage either).

However, if you are using it to measure and accept product, to need to know that it is accurate, and that it is being used in a manner that uncertainty and effectiveness is known...
 
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M

matt.simpson

Re: Calibrating or Verifying Tape Measures

What we did was to get a certificate of manufacturing tolerances (accuracy statement) from 2 vendors (Starret and Lufkin - now Cooper Tools) and these are the only brand that we use for any type of inspection. Their accuracy tolerances are tighter than our tolerances - at least for anything that would be measured with a tape measure. Other than that tape measures are just thrown out when damaged or the numbers start wearing.

Our auditor has had no issues with this.
 
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