My set of Class B precision gage blocks (0.050 to 4.00 inches) is three or four years old, and most of the mirror-finish blocks are still perfect. However, a couple of them are showing minor evidence of corrosion - probably from human fingerprints. I keep them slightly wetted with a spray coat of WD40 but not sure if that is the best protection. Any suggestions? Please don't tell me I have to use cotton gloves! Dave
LPS 3 works a lot better for corrosion protection than WD-40, but as expected its also harder to clean off. Anything that has better protection than WD-40 is going to have a slightly waxy feeling until you take it off.
Get Lano-Lube. That's what's called out by Starrett and others. It's a sticky lanolin gel you smear on. It washes off very well indeed in solvent, but when it's on it is a real good rust protector and it doesn't hurt your skin.
This isn't a "for sure" thing, but if these came from an economical source, there may be some problem with the wooden box. I think some woods are either "wet', or out-gas something that causes oxidation. I think I'd bake the box in the oven or a few hours, and then I'd do as someone else has suggested about LPS3, but spray the box instead, and re-heat it again.
As an aside, I used some unknown liquid which I thought was oil, but may have been either tapping fluid or brake fluid, as an "oil" for a stone to sharpen something. I then placed the stone back in the corner of a drawer of the tool chest, where it had resided with other stones for years. It was a week of so before I went back into that drawer, and there was oxidation of a "funny" kind forming on the shiny surface of a bunch of stuff in that drawer. Closer the stuff was located to the stone, the heavier the oxidation. I removed all the stones to an outside-the-box storage, and have had no further problems.
Brian Laws>My set of Class B precision gage blocks (0.050 to 4.00 inches) is three or
Thanks for all who contributed some very good ideas on corrosion prevention for precision gage blocks. Brian Lawson's response may have hit on an unsuspected source: the wood box itself, since the individual gages are fitted to narrow rectangular compartments. On a slightly different application, I have several home-made wooden storage holders for small end mills with 0.500 and 0.375 inch shanks. Some of these that are not used very much now show minor to moderate corrosion where the shank has been in long-time contact with the raw wood. A few quick passes with #600 grit aluminum oxide paper cleans them up ok, but obviously this is not recommended for gage blocks. Thanks to all. I am buying a tube of Lana-Lube. Dave
WD-40 is a water displacement agent. It is lousy at lubrication and rust prevention.
||My set of Class B precision gage blocks (0.050 to 4.00 inches) is three or ||four years old, and most of the mirror-finish blocks are still perfect. ||However, a couple of them are showing minor evidence of corrosion - probably ||from human fingerprints. I keep them slightly wetted with a spray coat of ||WD40 but not sure if that is the best protection. Any suggestions? Please ||don't tell me I have to use cotton gloves! Dave || ||
First off, for quite a while, I've been wiping Starrett "instrument oil" onto the ends of the gauge blocks before putting them away. More recently, I've been sprying with CRC 5-56 (or is that 3-56? -- something which sounds like a very fine pitched thread, but isn't. :-)
As an example, at work, I had an old set of collets for the Unimat SL-1000, which were all rusted. They were in a fitted wood case, with a sliding clear plastic lid. (Well -- sort of yellow clear. :-)
I got a new set of collets, and put them in that case, after spraying the inside with oil. They started to rust right away (a day or two). I finally pulled the plastic lid, and made a new one from Plexiglas, and the problems went away. I *think* that it was a cellulose nitrate which was starting to break down, and emit a gas which combined with moisture to become nitric acid.
I've since inherited the case, sans collets, and put my own collets in them, and again I have had no problems since the plastic lid was replaced.
I've got two sets of gauge blocks -- a smaller Chinese import set (used for rough-and-ready tasks), and a larger set of real "Jo" (Johansen) blocks, and with my treatment, I have had no problems with either set.
I use a light coat of CRC 3-36. I wipe with a lint free cloth before use anyway and I tested a stack of a bunch of the thinner ones. Any error due to residue was less than a tenth which is good enough for me. I have not the facilities nor (so far) the need to get down to microinches.