Jo Blocks Maintenance Question

[nickel-city-fab]

Yes, you CAN do better, but it gets maybe 50-100x harder with every decimal place

It also gets 50-100x more expensive which is difficult for the home shop guys to justify. I recall reading about the lengths that Moore Special Tool went to, to create the controlled environment for their master standards. Even back in the 60's it must have been many millions of $$$.

[J Tiers]

And, having the part and the blocks the same temp....... Many labs use a big chunk of metal on which the blocks and part are placed to come to equilibrium in temperature before doing the measurement. Then there is cleaning the blocks and part, handling so as not to disturb the temperature etc.


Luckily, since most home and commercial shops lack the means to measure down to the limits of gauge blocks, these things are less important. Repeatability to a couple tenths is about the best most any ordinary shop can even hope for. Yes, you CAN do better, but it gets maybe 50-100x harder with every decimal place

[Bented]

There are often facets of gauge block use that people ignore.

Ambient temperature is one such variable, many home shop metrology labs lack climate control.
Almost no home shops or commercial machine shops have the equipment to measure gauge blocks, how do you know that a .1009" block is accurate? It may be .10089"

[old mart]

Those blocks work quite well enough for our purposes, I rarely need to go below +-0.001". I do have some other standards which are in better condition if needed.

[tlfamm]

A list of gauge block refences (some given previously) from the "Knowlege Bases" favorite threads

NIST Gauge Block Handbook:
http://emtoolbox.nist.gov/Publicatio...nograph180.pdf

Federal Specification GGG-G-15C for Gage Blocks and Accessories:
http://www.everyspec.com/FED_SPECS/G/GGG-G-15C_16693/

Starrett recommendations for gauge block use and care:
http://www.starrett.com/docs/other-d...age-blocks.pdf

Mitutoyo Operation Manual for Gauge Blocks
http://www.mitutoyo.co.jp/eng/suppor...uge_Blocks.pdf

Mitutoyo History of Gauge Blocks:
http://www.mitutoyo.com/wp-content/u...Gage-Block.pdf

Early (1907/08) discussion of gauge blocks in "Accurate Tool Work" by Goodrich and Stanley, pp 183-201:
http://books.google.com/books?id=new_AQAAMAAJ&pg=PA183
http://books.google.com/books?id=new_AQAAMAAJ&pg=PA195

Prof. Hugh Jack on gauge blocks:
http://engineeronadisk.com/V3/engine...l#pgfId-141526

Popular Science (1942) on the manufacture of gauge blocks:
http://books.google.com/books?id=2SYDAAAAMBAJ&pg=PA108

Precision Measuring and Gaging (at HNSA)
http://archive.hnsa.org/doc/pdf/precision-measuring.pdf

[reggie_obe]

Gage block clean, recondition, testing, certification: https://youtu.be/mKzFXJCryrU?t=777
If you want the history of the Johannson Co., start at the beginning.

[J Tiers]

Checking the blocks with a tenths mike seems a bit backwards. I guess a case could be made by saying that it provides a rough check of the blocks and if they pass that then they are probably OK to check the (same) micrometer with.

Perhaps someone here can donate an old set.

I alluded to this earlier..... The discolored set will still be good enough to calibrate mics with, even tenths mics, even if it is "out" a few millionths.

Just what do you, or any of us, or most commercial shops, have, that would need closer measurement than tenths. And even if you DO have some such thing, do you have the proper temperature controlled room and correct procedures to do the measurements with any semblance of accuracy?

Smaller errors "can" come into play when stacking blocks. Two blocks have twice the "possible" error range of a single block, although the "probable" error is much less.

[Paul Alciatore]

Checking the blocks with a tenths mike seems a bit backwards. I guess a case could be made by saying that it provides a rough check of the blocks and if they pass that then they are probably OK to check the (same) micrometer with.

Perhaps someone here can donate an old set.

Anything more tham a gentle rub with an oily cloth risks more than the staining being left alone. You should the set we have at the museum, I scraped the rust off with a Stanley knife blade, they will never wring together, but they are all we have got and using up to three together has no measurable loss using a tenths micrometer.

[old mart]

Anything more tham a gentle rub with an oily cloth risks more than the staining being left alone. You should the set we have at the museum, I scraped the rust off with a Stanley knife blade, they will never wring together, but they are all we have got and using up to three together has no measurable loss using a tenths micrometer.

[rjs44032]

remove burrs? from hardened precision blocks?...

Um Yes!

Don't just take my word for it. See what Starret / Webber says: Stoning Gage Blocks


Best Regards,
Bob

[sarge41]

An oldtimer gave me a tip that may be useful at this time, regarding use and temporary storage during hot weather. After usage, when putting them away, wipe them down with silicone cloth. I sometimes use a paper towel soaked with spray silicon.
Sarge41

[wmgeorge]

Gee, thanks!

Did I really deserve that?

No Paul

[wmgeorge]

In this you would be incorrect, there are people in every hobby/business/pass time that exhibit similar behavior, as an example the person that runs the office where I work will only leave the building through the SAME door that they entered it at first, no exceptions.

People have firm beliefs that are often not rational yet makes them happy, let them have at it.

Correct J Tiers folks like Bented always seem to have answers maybe not related to the subject but that does not stop him.

[dian]

remove burrs? from hardened precision blocks? what might they have been used for? dont touch the blocks. if they wring they are o.k. if not, find an appropiate use for them. these are calibration devices.

[J Tiers]

In this you would be incorrect, there are people in every hobby/business/pass time that exhibit similar behavior, as an example the person that runs the office where I work will only leave the building through the SAME door that they entered it at first, no exceptions.

People have firm beliefs that are often not rational yet makes them happy, let them have at it.

Ah, so this is "compelled behavior" on your part? Just like leaving the building through the same door you come in through?

Well, then, we'll assume you cannot hep it, and just accept your peculiarities. Everyone has some.....It's OK 😉