Gage Block Calibration -- Who do you use?

Greebe · Mar 29, 2014

I have an older set of gage blocks that I need to send off for calibration. Who is a reputable service that I can send my gage blocks out to and not get charged a fortune?

Thanks,
Greebe

I previously asked this is the wrong forum section so I am reposting it here.

Davis In SC · Mar 29, 2014

Everyone I know in SC/NC uses Viking Gage/MSI in Duncan (Spartanburg) SC. They are set up to do almost any type of calibration.

The real Leigh · Mar 29, 2014

I use Webber Gage in Cleveland, which is owned by Starrett.

Webber Gage Division
24500 Detroit Rd.
Cleveland, OH 44145

- Leigh

DMF_TomB · Mar 30, 2014

always use and double check the error amounts listed after calibration.
i remember in manual machinist training making 1,2,3 blocks. we were told to indicate to 1,2,3 from gage block on granite table. i after mic my 1,2,3 block and get .9989 so i mic the 1.0000 gage block and it measures .9987, naturally i use my caliper too which is not reliable for measuring less than .001 error on 1" parts. so i check micrometer zero is zero and borrow another mic.
........ long story but everybody tells me i am measuring wrong but i insist i am doing correct and go to teacher. he checks and then we look at calibration report for blocks and find 1.0000 block is 1300 millionths undersize or .0013 under. the class of 20 all flunked the test with undersize 1,2,3 blocks. i was the only one to measure and insist something was wrong and why it happened. The class was suppose to learn always use the error amounts on inspection report and confirm gage block stack is the size you want with a micrometer

Fulcircleny · Mar 30, 2014

I use Holts Precision, South Windsor, Ct. Gage Calibration - Quality Control - Contract Inspection - Tool Repair - CMMs - CT, MA reasonable rates, and quick turn around

Regards,
Chris

Lambert · Mar 30, 2014

Any place with a certified metrologylab that doesn`t sell gageblocks themselves....

Greebe · Mar 30, 2014

Thanks guys. I also see that Mitutoyo Lab does them for $5.25 each or $425 for 81 piece set. Mine are an old set of Bureau of Standards but I guess they do any manufacturer. I believe some of the blocks are getting out of spec, mostly the 1-4" blocks. I mic'ed up the smaller sizes and they all seem pretty dead nuts.

Would an independent service be better than Mitutoyo.

Thanks,
Greebe

The real Leigh · Mar 30, 2014

Greebe said:
Would an independent service be better than Mitutoyo.

Any NIST-traceable calibration lab should give the same results.

These labs send their primary standards directly to NIST to be calibrated, then check your tools against those standards.

I would trust Mitutoyo implicitly. They are recognized world-wide as makers of the most accurate measuring equipment.
They make the equipment used by the calibration labs to compare the standards.

- Leigh

The real Leigh · Mar 30, 2014

DMF_TomB said:
... i mic the 1.0000 gage block and it measures .9987
... we look at calibration report for blocks and find 1.0000 block is 1300 millionths undersize or .0013 under

That exceeds the error limit for a grade A-S2 (loosest grade) block by a factor of 50.

The ASME limit is plus or minus 32 millionths for blocks up to 1" length.

- Leigh

Gordon B. Clarke · Mar 31, 2014

The real Leigh said:
That exceeds the error limit for a grade A-S2 (loosest grade) block by a factor of 50.

The ASME limit is plus or minus 32 millionths for blocks up to 1" length.

- Leigh

When I look at figures like that then I really appreciate working in µm

i.e 1µm = 0.00004" (OK I know 0.00003937" is more accurate) and 0.1µm doesn't look too bad either but there's a pile of zeros in the inch system to get right. I doubt if I could write "a millionth" in decimals without careful thought.

Gordon

The real Leigh · Mar 31, 2014

Gordon B. Clarke said:
When I look at figures like that then I really appreciate working in µm

But the OP is in the US, and the block dimension was stated in inches.

The Mitutoyo catalog (and the ASME spec) give the tolerances in both metric and inch systems, in separate tables.

I appreciate working in the units that the OP presented, rather than doing conversions.

- Leigh

Gordon B. Clarke · Mar 31, 2014

The real Leigh said:
But the OP is in the US, and the block dimension was stated in inches.

The Mitutoyo catalog (and the ASME spec) give the tolerances in both metric and inch systems, in separate tables.

I appreciate working in the units that the OP presented, rather than doing conversions.

- Leigh

I think you're reading too much into my post. I only meant I found it easier to wrap my head around µm than millions of an inch.

Of course if my gauge blocks were in inches I'd expect the calibration results to be in inches and if they were metric then in µm.

BTW in the OP nothing was mentioned about inches - just gage blocks but as the poster was American it was assumed inches

Inches didn't crop up until post #7.

Gordon

drgnrider · Mar 31, 2014

Greebe said:
Thanks guys. I also see that Mitutoyo Lab does them for $5.25 each or $425 for 81 piece set. <snip>

Would an independent service be better than Mitutoyo.

Thanks,
Greebe

The real Leigh said:
Any NIST-traceable calibration lab should give the same results.

These labs send their primary standards directly to NIST to be calibrated, then check your tools against those standards.

I would trust Mitutoyo implicitly. They are recognized world-wide as makers of the most accurate measuring equipment.
They make the equipment used by the calibration labs to compare the standards.

- Leigh

I agree with Leigh about all labs sending their standards off to NIST as well as Mitutoyo's reputation. For Gage Blocks, my cal-lab in Southern Kansas charges $2.85 ea for Length Only or $3.85 ea for Length and Parallelism.

It comes down to the "risk" of cost vs. reputation. While low cost is good, if the lab's reputation is questionable...

ewlsey · Mar 31, 2014

DMF_TomB said:
the class of 20 all flunked the test with undersize 1,2,3 blocks. i was the only one to measure and insist something was wrong and why it happened. The class was suppose to learn always use the error amounts on inspection report and confirm gage block stack is the size you want with a micrometer

That's the stupidest test I have ever heard of. A machinist needs a standard he can rely on to check parts against. For many jobs, that is the gage block. If your block is that far off, it should be thrown out and replaced.

I would recommend checking your micrometer against gage blocks, not the other way around. Your micrometer can't measure in millionths.

drgnrider · Mar 31, 2014

ewlsey said:
That's the stupidest test I have ever heard of. A machinist needs a standard he can rely on to check parts against. For many jobs, that is the gage block. If your block is that far off, it should be thrown out and replaced.

I would recommend checking your micrometer against gage blocks, not the other way around. Your micrometer can't measure in millionths.

I agree. As a machinist, at what point do I take the assumption that I don't need to check farther? if my company says this is a good standard, then why should it be questioned? Why should the machinist have to get the certificates? If he questions this standard, why not the cal-lab's standards, where does it end?

Now, as the company's calibration person and ISO auditor, yes I should question the cal-labs certs given to me if something does not look right and ensure they have some traceability to NIST.

tdmidget · Mar 31, 2014

DMF_TomB said:
always use and double check the error amounts listed after calibration.
i remember in manual machinist training making 1,2,3 blocks. we were told to indicate to 1,2,3 from gage block on granite table. i after mic my 1,2,3 block and get .9989 so i mic the 1.0000 gage block and it measures .9987, naturally i use my caliper too which is not reliable for measuring less than .001 error on 1" parts. so i check micrometer zero is zero and borrow another mic.
........ long story but everybody tells me i am measuring wrong but i insist i am doing correct and go to teacher. he checks and then we look at calibration report for blocks and find 1.0000 block is 1300 millionths undersize or .0013 under. the class of 20 all flunked the test with undersize 1,2,3 blocks. i was the only one to measure and insist something was wrong and why it happened. The class was suppose to learn always use the error amounts on inspection report and confirm gage block stack is the size you want with a micrometer

In a shop where grammar is not required that is probably close enough.

scadvice · Mar 31, 2014

Why don't "you all" correct me if I'm wrong here. Most shop do not require super, super accurate gage sets. i.e. a 3k set. What is wrong with this set and just buying a new one each calibration cycle and e bay the old set?
https://www.mscdirect.com/product/06450738?Arg=nv

Just playing devils advocate...

:popcorn:

The real Leigh · Mar 31, 2014

Quality assurance is a process, all aspects of which must be identified and specified to achieve the desired results.

You cannot pick an item in isolation and claim that it fulfills any particular requirement without analyzing how it works in the system.

Different shops require different levels of precision.
In the shops of my acquaintance, new measurement equipment must be calibrated and certified independently just like used gear.

Any certs supplied with new equipment are of interest to identify the accuracy level of the equipment, but are not accepted per se.
This is exactly like buying used equipment which has current cal certs.

- Leigh

scadvice · Apr 1, 2014

Yes, it is a process. However, in the general machine shop environment, I could argue in an audit, that the example I gave as gage blocks are acceptable because they are traceable to NIST, within a reasonable amount of time and use, so I need to go not further than that, as any other demands are unreasonable.
The requirement of independent certification has been satisfied.

All other measuring devices are inspected off of these gage blocks ( and an optical flat, also replaced each year) and documented.

The one exception is our CMM, we get it re-certified each year by an independent.

Respectfully, I guess I do not agree with your last sentence and we have yet to fail an audit.

Gordon B. Clarke · Apr 1, 2014

I don't know how often it's done or if it has ever been done but some "Agency" should anonymously send the same items in turn out to approved calibration facilities to see if, or by how much, results vary.

I heard that that was tried in Europe (urban legend?) and that the results were not especially good i.e. not identical within the measurement uncertainty. The question still remains - WHO got it right?

Gage Block Calibration -- Who do you use?

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