Cleaning a micrometer

[wch]

I bought an old Starret micrometer at a flea market really cheap; it has seen some neglect, so much that the engraved measurements on the handle and on the side have been smudged over by light rust and some corrosion.
Has anyone an idea as to how I could gently go about cleaning the tool so that I can read the indices again?
Thanks

[JonB_in_Glencoe]

for just cleaning the rust off the outside,
I'd start by using kroil (or your favorite penetrating oil) and denin or a clean shop rag.
if that doesn't do enough for you, then go to 0000 steel wool.
Jon

[frnkeore]

I would suggest Muratic acid applied with a Q-tip. Let the acid set about 1 min and rince. Keep apply until the metal is bright. When finished rince it in a baking soda and water solution, then warm it to dry and oil it well.

Frank

[largom]

OOOO steel wool will clean the rust off.

Larry

[John Boy]

wch, Take this to the bank and forget about the other suggestions ... a 50:50 mix a ATF and acetone to lift the rust - then Bronze Wool, not Steel Wool

[imashooter2]

wch, Take this to the bank and forget about the other suggestions ... a 50:50 mix a ATF and acetone to lift the rust - then Bronze Wool, not Steel Wool

For a precision instrument like a micrometer, this is the way I'd go as well, although I have no issue with using 4 aught steel wool. This mix will lift the external rust with no danger to the internals that you might get from water bearing products like acids.

How do the anvils look?

[wch]

The anvils look fine; if there is any corrosion or gunk on them, I can't see it, even under magnification.

[wch]

I want to say thanks to everyone who has replied!

[3006guns]

Wait! You're not done yet! If you run the spindle all the way down and it shows zero on the thimble, that does NOT mean it's automatically accurate. You need a micrometer "standard" for adjustment...a piece of ground, polished bar that is precisely 1" in length (or longer, depending on the capacity of the mic) at room temperature. Gently run the spindle down until it touches the ends of the bar and note your reading. If it zeros on 1", you're good. If not, you will need the little spanner wrench for adjustment...available Starret or a number of suppliers. Instructions for adjustment are available on line also.

Having said that, a micrometer standard is expensive so another method would be to compare your mic against one that is known to be accurate. Just measure a piece of bar stock with the first mic, then adjust yours to match. If all else fails a good machine shop with a sympathetic machinest would probably help you.

They're a wonderful, simple tool that will last for years with any care at all.

[imashooter2]

Wait! You're not done yet! If you run the spindle all the way down and it shows zero on the thimble, that does NOT mean it's automatically accurate. You need a micrometer "standard" for adjustment...a piece of ground, polished bar that is precisely 1" in length (or longer, depending on the capacity of the mic) at room temperature. Gently run the spindle down until it touches the ends of the bar and note your reading. If it zeros on 1", you're good. If not, you will need the little spanner wrench for adjustment...available Starret or a number of suppliers. Instructions for adjustment are available on line also.

Having said that, a micrometer standard is expensive so another method would be to compare your mic against one that is known to be accurate. Just measure a piece of bar stock with the first mic, then adjust yours to match. If all else fails a good machine shop with a sympathetic machinest would probably help you.

They're a wonderful, simple tool that will last for years with any care at all.

LOL! We just had a thread a little while ago with advocates saying you needed standards accurate to millionths of an inch and you had to check the micrometer ten places along its range.

Frankly, unless you are working in a serious machine shop, check zero and some feeler gauge and if it meets those standards call it good.

[JIMinPHX]

brass brush, bronze wool, penetrating oil & elbow grease.

Then check it on a set of standards in at least 4 or 5 places in the middle of it's measuring range & pray for the best.

[MikeS]

I see you have several suggestions already, but let me give you another. Get some Evapo-rust, and let it soak in that overnight. In the morning you will have a rust free micrometer! After you rinse off the Evapo-rust you will have to make sure you oil it well, otherwise it will rust fairly quickly. Personally I would dip it in ATF or some other light weight oil after de-rusting it. You can save the Evapo-rust, and re-use it. Along with being a VERY good rust remover, it's also one of the safer ways of doing it. The only thing to watch out for is it will remove blueing, as blueing is a form of rust.

[a.squibload]

I salvaged a free mic with citric acid and light gun oil,
citric will attack rust if the solution is strong enough,
won't attack the metal.

[Blanket]

a small piece of leather with a little ATF on the tanned face makes a good cleaner for minor surface rust, can add a little JB bore paste to the mix if needed. Don't forget to clean well with a solvent that evaporates ( I like plain old 93% rubbing alcohol) and lightly reoil with a good instrament oil such as Starret. As stated check the contact surfaces and hold up to a light to make sure they are square to each other and check with a standard....Russ