Gauge blocks/plates restoration question.

darkestremedy · Mar 5, 2019

Good time of day everyone!

I have recently laid my hands on a set of class two plates.. set number one (83 plates in box) but sadly some are rusted... they do not stick to each other too when i tried to combine some of them.

It is a used set as well... a USSR tool, which i hold too dear and want to restore. I know these plates MUST NOT be grinded, buffed or even polished....

So i have question for you, specialists... what is the best way about making them useful again?

I know you can use glass for fine surface.. but i couldn't find any other viable source of information on restoration or tare of these types of tools.

I have experience in restoration of micrometers and other calipers. But this tool set is too precise, nothing like the things i have worked on before... and i am very afraid to f*ck up the surfaces any further then their current state... since the rust already ruined the stickiness of some of the plates.

Thank you everyone in advance for assistance.

Best regards,
~Twilight

Edit:
P.S. photos provided!

rjs44032 · Mar 5, 2019

Class 2 Gage block can be deburred carefully with precision flat stones. I would remove the rust first. Then lap using them. They wont be pretty but they may ring again (depends on the amount of damage). Here are a few links:

GF5.pdf - Google Drive

GD&T Precision Ground Flatstones | IIGDT

Flat stones for fine finishing | Cutting Tool Engineering

Edit: After posting this it occurred to me that the cost for Asian Class 2 gage blocks may be less than the time spent trying to recover these. I've seen sets for less than $90 U.S. recently.

Gage Block Set in Wood Box, +/-.000050" Accuracy, 81 Piece

Best Regards,
Bob

darkestremedy · Mar 5, 2019

More images!

darkestremedy · Mar 5, 2019

rjs44032 said:
Class 2 Gage block can be deburred carefully with precision flat stones. I would remove the rust first. Then lap using them. They wont be pretty but they may ring again (depends on the amount of damage). Here are a few links:

GF5.pdf - Google Drive

GD&T Precision Ground Flatstones | IIGDT

Flat stones for fine finishing | Cutting Tool Engineering

Edit: After posting this it occurred to me that the cost for Asian Class 2 gage blocks may be less than the time spent trying to recover these. I've seen sets for less than $90 U.S. recently.

Gage Block Set in Wood Box, +/-.000050" Accuracy, 81 Piece

Best Regards,
Bob

Gratitude for your knowledge, Bob!

I will read tonight!! (i got mine for less then 5 dollars by the way, but in my country's currency) Forums i tried in my homeland country were utter sh*te and absolutely useless in terms of restoration of such equipment..

Big problem to me is that this is USSR set of plates... and i want to restore it very badly. It is also my first set of such tools. So it bears a lot of sentimental value to me.

Thank you again for your wisdom.
Best regards,
~Twilight

rjs44032 · Mar 5, 2019

Ok, I posted my response before the pics were posted. Now that I'm seeing what appears to be considerable wear on them, I recommend pursuing the restoration of these just for shop use - not inspection. You can deburr them with precision flat-stones, but they will not ring unless they are geometrically flat and polished. They appear to be well-used in the pictures.

As an aside, I have had some success removing minor flash rust with powder solvent, then deburring using the flat stones. Hope this helps. Good Luck!

Best Regards,
Bob

Rob F. · Mar 5, 2019

Do a search on rust removal on here. Molasses soak might do it. Not sure if you can get evap-o-rust over there.

Gordon B. Clarke · Mar 5, 2019

Rob F. said:
Do a search on rust removal on here. Molasses soak might do it. Not sure if you can get evap-o-rust over there.

Here are some suggestions. Might be an idea to try one after the other on one block first.

YouTube

I agree with rjs. Just use them for shop inspection and not calibration.

darkestremedy · Mar 5, 2019

Thank you for advice!!

I will read about this molasses thingy! I have used vinegar befoer, but it only helps with stains. This rust is not just stain, sadly.... it sticks out of surface...

I have a powerful battery charger and starter that i had salvaged and use every time for electrolysis based rust removal... (as it is most suitable option where you do not lose any metal from restored part's body) but is it safe to use on gauge blocks? Like i have stated before.... i am very paranoid about this equipement... first time working with such precision tools and i do not want to ruin it.

Best regards.
~TS

Paolo_MD · Mar 6, 2019

TS,
I see considerable pitting, likely resulting by uneven alloying of the steel (as far as I know, it's a rather common problem of old hard steel alloys).
Molasses and Evaporust are "chelating agents" which act by wrapping around only rust molecules, leaving undisturbed any pure metal surface, similarly to what electrolysis does. The difference with electrolysis is that they act evenly on any surface and not dependent upon the path to the electrodes.
Vinegar and other acids would attack also the clean metal and it should be avoided in this case.
Given that the alloy doesn't seem very homogeneous, you will risk some more pitting even with the other methods.
One more thing: if the lettering on the blocks is just superficial electro-etching, you risk that it will be almost completely lost during derusting.
In absence of a ground flat stone, your second best option is to polish them by robbing them on the surface of a granite plate.

Paolo

darkestremedy · Mar 7, 2019

Paolo_MD said:
TS,
I see considerable pitting, likely resulting by uneven alloying of the steel (as far as I know, it's a rather common problem of old hard steel alloys).
Molasses and Evaporust are "chelating agents" which act by wrapping around only rust molecules, leaving undisturbed any pure metal surface, similarly to what electrolysis does. The difference with electrolysis is that they act evenly on any surface and not dependent upon the path to the electrodes.
Vinegar and other acids would attack also the clean metal and it should be avoided in this case.
Given that the alloy doesn't seem very homogeneous, you will risk some more pitting even with the other methods.
One more thing: if the lettering on the blocks is just superficial electro-etching, you risk that it will be almost completely lost during derusting.
In absence of a ground flat stone, your second best option is to polish them by robbing them on the surface of a granite plate.

Paolo

Thank you for advice, Paolo!

I can use my electrolysis machine fine, just gotta figure out ways to contact to plates without scratching them any more as they are....

Markings on the plates are seem to be laser~engraved. Quite deep, too, especially on wider plates.

After reading Bob's links i was able to find some of these "deburring" stones. A terminology new to my knowledge. Would these suffice for clearing the surfaces without damaging them much? This set of stones on Aliexpress Aluminium oxide stone 3 pieces200# 400# 600# deburring and smoothing the snowboard edge works with most edge tuners-in Skiing Gloves from Sports & Entertainment on Aliexpress.com | Alibaba Group

I'll derust all of the plates as soon as i finish preparing the box. (it is wooden and a lot of chips are inside... i want to make sure all the plates stay secure and 100% scratch~safe in there...) I just hope they will "stick" together after restoration.

Thanks again for all your help.

Best regards,
~Twilight

darkestremedy · Mar 7, 2019

P.S.: i know these stones are stupid and childish idea because it is too cheap, but i try to save up as much on restoration and still make it as good as it was back in the day. Stones that Starret makes for such purposes cost too much. Way out of my league...

AD Design · Mar 9, 2019

Before you finish preparing the box they'll be stored in you may want to research the wood species that will further oxidize/corrode your plates. There are several species that should not be used for storing precision steel components when they are in contact with the wood itself. It would be horrible for you to discover this the hard way after your efforts. Good luck.

darkestremedy · Mar 9, 2019

Thank you!

This is good intel indeed.

But i am just polishing the original one. Besides i am confident in what Soviet Union was using for it's creations. This box is pretty great. I am planning on keeping them in engine oil as well to hide them from corrosion. Plus i wanted to place soft material in the slots where to place the plates!

Will post pictures here most likely!

Best regards,
~Twilight

M Stewart · Mar 12, 2019

Sorry for a late post - I've had domestic plumbing matters to attend to.

Some years ago, I bought a set of Tungsten Carbide gauge blocks, and on delivery many of them were "oxidised" or tarnished, and certainly didn't wring one to another. I searched widely, including here, and tried gently rubbing their surfaces on a granite surface plate in a figure of eight pattern. This removed the tarnish and in many cases they would then wring to each other, and to the optically flat anvil of my Mitutoyo Comparator. Initially,there was quite a lot of resistance when rubbing the blocks on the granite plate, but after a short period, this lessened, and after this was when I rechecked whether they would wring to each other. I think I checked a few of them against optical flats with good results, but to be certain, that would require me to refer to my notes.

Further searching, and I found that my "technique" seemed to be endorsed by one of the National Standards labs.

4GSR · Mar 12, 2019

I tried the Evaprorust. Don't do it. It made a bigger mess that pretty much destroyed the gage blocks. for any use that I tried it on. They'll be okay for checking a slot and such where you are not working in 'tenths". Found the best method to take fine wire wheels that you would use in a Dremel tool. Buff off the rust with it. Then I rubbed them against a fine grit flat Indian stone that I knew was flat, a couple of strokes, slowly. Last rubbed against a Norton Hard Arkansas stone a few times to get a somewhat mirror finish. Never thought about rubbing them against a granite surfece plate. They won't be perfect or calibrate to within a couple of millionths, but will be fine for setting up sine bar or measurement that don't have to be that close. The only way to get them to wring ever again is to send them to a gage lab that can re-lap them. Doing so may bring them into a new dimensional state and have to be remarked. KenS.

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