Gage Block Care & Feeding

[pete]

As I said Ron my first set of imperial grade 2 were Chinese, the second set I got a very good deal on an unopened box of NOS grade 2 Mitutoyos. The Mitutoyo set are my calibration standards for everything else. The Chinese one's are my shop blocks used during some set ups ect. Even as shop blocks I still treat them pretty carefully. So what do you get from Mitutoyo for roughly 4 or more times the price over the Chinese blocks. Well I believe Mitutoyo's over/under certification measurements for the blocks exact size at the time they were manufactured and have some real doubts about the Chinese certification. For the price I'm betting that certification is completely bogus and not worth the paper it's printed on. The Mits wring together far easier and have a much better lapped surface. 2 of the smaller blocks in the Chinese set were duplicates but Penn Tool in New Jersey sent me a grade 2 Mit. block to replace the duplicate. I've got a Mahr 20 millionths indicator and one of these days I'm going to take some time and compare the 2 sets against each other. When I do I'll post the results here. Personaly I think the Chinese sets should be good enough for a home shop, but I'd still want to double check there measurements with a good mike just to be sure nothing is off or has been mismarked for size.

To me having a set of gage blocks is no different than having a surface plate and a good cylindrical square. There all known shop accuracy standards so that you have a basic building block for checking other items. + - .001" for your average shop work is likely around what most of us are doing as well. Setting a sine bar and double checking a tool taper takes a lot better than that tho. Depends on what your checking, but it's pretty slow going trying to verify most items with or against gage blocks. The good part after you do then you KNOW for sure it's correct or not if the blocks are correct. I went for a long time without gage blocks and just used a set of Starrett adjustable parrallels preset with a mike to the required size. I still use that method sometimes even with the gage blocks.

For grade 2 blocks and "if" there accurately following the NIST standards then the following applies for an allwable size variation. 1" +4 -2, 2" +8 -4, 3" +10 -5, 4" +12 -6 that's millionths of an inch deviation. So that 4" block has to be within that 18 millioths of the true size to meet the grade 2 specification. A grade 3 set you can double those numbers. My Mit. set falls roughly in the middle of the allowable limits for the majority of the blocks.

[Cary Stewart]

Related to the comment about gage blocks and other steel pieces growing and shrinking is the following. l read a couple or more years ago that the International Standards Organization has found that the Platinum-Iridium meter bars that from the late 19th century were the absolute standards would wide. The master is in France but very accurate duplicates were made for other countries. USA, Japan, England, Australia (I think)
, Germany and probably Switzerland all received these 1 meter bars. Now fast forward to present time. The meter is defined by a wave length of lite. Soooo the metrology guys measured all the 1 meter bars all over the world. They found that no two were alike and even the one in France has changed length. The combination of metals used was thought to be absolutely stable if stored in a Temperature and Humidity controlled environment. They are still scratching their collective heads as to why.
Cary

[Dragon]

I acquired a class 3 (A&B) set of gage blocks at a great price. New, but apparently manufactured in 2001 in China. They came with each block wrapped in wax paper. I removed the paper, and tried to clean the was using 91% isopropyl alcohol. That helped, but still left a wax film on the blocks. Then, for some of them, I tried washing them in soapy water (dawn dish soap), that also helped, but not very much (they were thoroughly dried afterwards).

How do I get the blasted wax off completely without damaging the blocks? Vinegar might work, but may well harm the blocks, so that probably isn't a good idea. Likewise with citrus based products. The blocks aren't really usable with the wax film coating them.

[Inspector]

I think Acetone would work.

Pete

And welcome to the forum.

[Harold_V]

I find it strange that many refuse to acknowledge the fact there are readily available solvents on the market that will fully remove hydrocarbon protectants.

Have you given any thought to using one of them? I offer Stoddard solvent as an example, or even common paint thinner. Both of them have the ability to fully remove the applied material and do so without any risk of damage.

I am at a loss to understand why one would even consider the use of vinegar. It's great for sharpening an old file, which is precisely why it shouldn't be a candidate for use as an oil solvent.
H

[liveaboard]

Cyclo carburetor cleaner from an auto parts store will do the job.

[Dragon]

I have given consideration to using readily available solvents -- I am just not familiar with them. Hence the question. I did consider acetone, but didn't know if it would work. Wax appears to be really hard to get off without potentially damaging the gage blocks. I don't know if acetone will affect steel or not. Outside of this application, vinegar is generally a very good cleaning agent. Mineral spirits might be a good choice as well, I don't see a problem there. Note that Stoddard solvent appears to fairly pricey.

[NP317]

Use mineral spirits.
RussN

[Inspector]

Acetone will remove oil and wax but it will leave a chemically clean surface that can rust quickly so I should have said to coat them with a light oil after cleaning.

Stoddard solvent is the main ingredient of solvents more commonly named by their maker. Varsol by Esso, Shellsol by Shell, etc. Reginal usage of the name also comes into play. As an aircraft mechanic in Western Canada I knew what Stoddard solvent was but never heard anyone refer to it. Varsol was generally spoken no matter what the brand. Mineral spirits and paint thinners (what I think Harold meant when he said paint removers) are similar products. They are used for cleaning of greases and oils but do leave a thin film of oil behind which in the case of gauge blocks is a good thing.

The only place I have ever seen vinegar used is for household cleaning and for french fries. They don't taste good with Varsol on them.

Pete

[Dragon]

Thanks, Pete. Don't forget pickles, sauerkraut, pickled eggs, etc. Vinegar is used in lots of foods, and is often used for household cleaning. It is event taken orally for health purposes. Actually, while I like some pickled foods, I don't like vinegar on french fries.

Looks like mineral spirits are the best choice, especially from a cost standpoint. Won't the oil film conflict with using gage blocks, wringing, measuring, etc.? That can always be removed with soap and water (with immediate, through drying, of course).

[Inspector]

You wipe the oil off with a soft dry cloth when you want to use them. Leave the soap and water in the bathroom.

Pete

[Dragon]

Thanks. I have another question about gage blocks. My understanding is that the length of each gage block is reduced by the "wringing distance" so that a stack of blocks only is short by a single wringing distance. Where that distance is the distance between two wrung blocks. And that single wringing distance can be eliminating by wringing the stack to "base" block. Obviously, the wringing distance is very, very small -- but I have been unable to find exactly the size of that distance. Does anyone know?