Cleaning gage blocks.

cobalt blue · Aug 21, 2014

I have a set of older gage blocks and some of the blocks have stains on them. Is a product like Flitz safe to use to lightly clean the stains off or will I ruin them by doing this.

cobalt blue

DMF_TomB · Aug 21, 2014

gage blocks

cobalt blue said:
I have a set of older gage blocks and some of the blocks have stains on them. Is a product like Flitz safe to use to lightly clean the stains off or will I ruin them by doing this.

cobalt blue

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i just use paper like you put in a inkjet printer. i rub gage blocks on paper (a few sheets thick) on a flat surface to clean. very mild abrasive action. probably take many decades to notice any effect from cleaning.

PeteM · Aug 21, 2014

One factor is your intended use. If it's for general home shop use, a bit of oil and the finest abrasive you can find (probably finer than "Fritz") might make you happier with the staining. DMF's suggestion is a good one.

In general, manufacturers provide only a very hard stone for removing dings. And then a calibration check.

A lot of us use blocks only occasionally. Best to keep them oiled or greased in between, carefully removing that prior to use and reapplying after.

michiganbuck · Aug 21, 2014

DMF_TomB said:
.
i just use paper like you put in a inkjet printer. i rub gage blocks on paper (a few sheets thick) on a flat surface to clean. very mild abrasive action. probably take many decades to notice any effect from cleaning.

I do much the same with a spot of spindle oil on the paper and the paper on a true flat surface..Hydraulic oil would be good also IMHO. I do have a very fine ceramic stone for that but don't think that a good thing to do.

The real Leigh · Aug 21, 2014

You don't want to do anything to the measuring surfaces. They should have a light coat of oil at all times. That's all.

A very thin film of oil must remain on the mating surfaces when using the blocks. Do not clean it off.
That thickness is included in the dimension that appears on the calibration certificate for the block.

It's unlikely that a simple stain would affect the block's dimensions. If it's rust or corrosion, that's a different story.

The other four surfaces don't care. You can use whatever you want.

- Leigh

PeteM · Aug 21, 2014

Some gage block makers included a small tin of protective grease (the consistency of vaseline) in their sets. It was meant to be applied for protection, wiped off for measurement.

Here's Starrett on cleaning blocks before and after use: http://www.starrett.com/docs/other-...se-care-of-precision-gage-blocks.pdf?sfvrsn=3

The real Leigh · Aug 21, 2014

PeteM said:
It was meant to be applied for protection, wiped off for measurement.

The writeup from Starrett is somewhat misleading.
The blocks should be wiped off as suggested to remove any large amount of oil or other material.
They should not be "cleaned", as in removing all traces of lubricant.

A thin film of lubricant should remain.
In fact, the thickness of that film on one surface is included in the certified dimension as shown on a Certificate of Calibration.

I recently posted the quote from the Gauge Block Handbook published by NIST.

- Leigh

PeteM · Aug 21, 2014

The real Leigh said:
. . . However, a (very) thin film of lubricant should remain. . . .

Agreed.

Most folks end up slathering on oil or grease for corrosion protection; which is just fine as all but the thinnest layer remains for measurement.

Mud · Aug 21, 2014

The real Leigh said:
A thin film of lubricant should remain.
In fact, the thickness of that film on one surface is included in the certified dimension as shown on a Certificate of Calibration.
- Leigh

How thick is that film?

John Garner · Aug 21, 2014

Starrett's Webber Gage Division describes their recommendations for care, handling, and maintenance of gage blocks in greater detail on their website than Starrett goes into on theirs. I suggest spending a few minutes at the Webber website, which includes this page Use and Care of Gage Blocks

The real Leigh · Aug 21, 2014

Mud said:
How thick is that film?

The physics and characteristics of the "wringing film" are not well understood, even in the modern era.

The thickness can vary from one wring to the next of the same exact pair of blocks.

Appendix B (pgs 134-136) of the Gauge Block Handbook addresses wringing films specifically.

It includes the statement:
"Generally the thickness is about 10 nm (0.4 μin), but some wrings will be over 25 nm (1 μin) and some less than 0."

- Leigh

specfab · Aug 22, 2014

The real Leigh said:
...

The other four surfaces don't care. You can use whatever you want.

- Leigh

My preference is a 9" right-angle grinder with 60-grit sanding disc. That'll get rid of those stains. ;-)

DMF_TomB · Aug 22, 2014

i have never oiled gage blocks and never had a problem wringing them together unless badly scratched from abuse. coolant seems to supply all the oil necessary for me.
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i always check micrometers to gage blocks. anytime they disagree more than 0.0002" i sent in for calibration.
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basically when i use micrometer and gage blocks i am seeing if they agree with one another and they usually do with the adjustable micrometers being in error 99.999% of the time. i have once seen a gage block undersize 0.0013. i suspect that was somebody try to "fix" a badly scored block that would not wring anymore or it was a "test" for the machinist students in the school shop. i was the one who caught it and asked the teacher about it who confirmed it when he read inspection report
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i have never seen gage block come back from testing more than 0.0001" undersize normally and we tape the undersize numbers to the gage box lid so when open it is obvious to read the error amounts. thats why they make .1001, .1002, .1003, etc to .1009 blocks

Mud · Aug 22, 2014

I have this DoAll gage block Dressing Plate. I haven't seen any reference to it or to anything like it other than Starrett's Gage Block Stone. Anyone else use one or know about this?

It measures 1 X 2 X 3.5", and appears to be granite.

cobalt blue · Aug 22, 2014

Thanks for all the thoughtful input. I have printed the documents with links to review in a more leisurely time.

I was not aware of the Gage Block Handbook by NIST. I will go to their site and see how much they want for that bad boy. "Formal Education" is always so expensive. I do wish all the standard administrators, would make Standards more affordable for all of us. I have always thought they would make more by wider distribution. Thanks Leigh for sharing that bit of information.

The Doall information from the "gage block dressing stone" photos is priceless as well. Starrett sells the stones, but I don't know if they come with instructions. Thanks for that tidbit from Mud.

I see now that the Gage Block Hdbk from NIST is available as a PDF in the first "sticky" by Leigh, so disregard my whining about expensive Standards.

Cobalt blue

The real Leigh · Aug 22, 2014

cobalt blue said:
I was not aware of the Gage Block Handbook by NIST. I will go to their site and see how much they want for that bad boy.

Hi Blue,

It's free.

Also known as Monograph 180. Unfortunately it's undated. The NIST site shows it as 1995.
Note that they use both "gage" and "gauge" spellings within that publication.

Here's a link to it on the NIST site:
emtoolbox.nist.gov/Publications/NISTMonograph180.pdf

- Leigh

Pete F · Aug 22, 2014

John Garner said:
Starrett's Webber Gage Division describes their recommendations for care, handling, and maintenance of gage blocks in greater detail on their website than Starrett goes into on theirs. I suggest spending a few minutes at the Webber website, which includes this page Use and Care of Gage Blocks

According to them, the only reason to leave a film on the block during use is to prove some protection against corrosion during use. They also say that alcohol can be used to clean the blocks, but as it leaves no film offers no short term protection. I've seen the same elsewhere, where blocks are fully cleaned, and no mention of leaving any film behind for anything other than protection.

The real Leigh · Aug 22, 2014

Pete F said:
I've seen the same elsewhere, where blocks are fully cleaned, and no mention of leaving any film behind for anything other than protection.

In the US, NIST sets the standards. That's their job, by law.

They say the film exists, and that one film thickness is included in the length shown on NIST-traceable Certificates of Calibration.

What any other entity or firm says is simply irrelevant.

- Leigh

Pete F · Aug 22, 2014

The real Leigh said:
In the US, NIST sets the standards. That's their job, by law.

They say the film exists, and that one film thickness is included in the length shown on NIST-traceable Certificates of Calibration.

What any other entity or firm says is simply irrelevant.

- Leigh

My God Leigh, you really do come up with some bizarre statements at times. I'm aware of at least 2 credible gauge block MANUFACTURERS (Starrett and Mitutoyo) who make NO allowance for any film in using their own blocks. For measurement purposes it is immaterial in any case. If you're concerned about that film, you're using the wrong tool for the job! To state that what manufacturers says about their own (certified!) products is "irrelevant" is just bizarre!!

As has been asked by others above, what is the thickness of this film? According to the linked Gauge Block Handbook, it is both variable and unstable, so I'm curious as to what thickness the North American Standards specify.

Out of interest, here is Mitutoyo's take on "irrelevance" http://www2.mitutoyo.de/uploads/media/poster_gauge_blocks_01.pdf they echo Starrett's caution about not using alcohol to clean the blocks, however again it's for concerns about corrosion and no mention about what size film to leave to meet US standards.

The real Leigh · Aug 22, 2014

Pete,

Metrology is a science and discipline defined by international standards and procedures.

It's not a menu, where you pick and choose what you want to follow, and what you want to ignore.

Quite possibly the folks who wrote the text you linked might not even know about wringing films, or considered them insignificant.
Given that US and ISO standards are in lock-step as regards dimensional measurements, I'm sure the ISO standards are the same as the US.

The admonition against using alcohol is because it would remove the wringing film.

You obviously have not read Appendix B in the Gage Block Handbook, which I linked previously. It explains the issue in great detail.

- Leigh

Cleaning gage blocks.

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