How do indicators age?

I like older Mitutoyo 1" travel indicators. I haven't bought a new one for a long time but if they're still made the same then the older ones are good. Indicators branded "Westhoff" used to be made by Mitutoyo. They may still be. The Mitutoyo test indicators should be avoided. Things to look for when buying a used travel indicator: Check the fit of the moving rod. There should be no discernable side play. Check to see if thickened oil is making it drag. The sleeves the rod runs in, which are attached to the body of the indicator, can be knocked out of alignment. This will prevent the rod from moving without drag. They can be pushed back into alignment. If this is done too many times they will get loose. So grab the indicator body and apply gentle pressure to the sleeve and see if the rod starts to drag. Check for smooth travel of the rod. Look for grit in the gear teeth on the rod and the gear that rides on the rod. These teeth should not be visible without removing the back of the indicator. So there should be no way for chips to get in there. But they do. Osmosis or something. You know, less chips inside, more chips outside, so the chip pressure is higher outside and they pass through the indicator case in an attempt to equalize the chip pressure. Inside is a thin, short, rod with a spring attached that is pressed into the moving rod. They can become loose. This can be fixed with the careful use of loctite. Someone may have taken apart the indicator and not put it back together with the backlash removed. The gear train is spring loaded such that the gear that rides against the rod is always trying to push the rod out. This is how the lash is removed. The indicator can be put together without the proper loading of the gear train. Finally, the hands may not be tight on their shafts. Check this by first setting the indicator to zero and then tapping the tip of the indicator sharply with your finger. Don't go overboard though. The hand should return to zero. It's harder to see if the little hand is loose but they almost never get loose. But the big hands do. So if the big hand is a little loose it will lose or gain motion in the same direction so that it will get farther and farther away from zero. If it's really loose it will end up on either side of zero depending on how hard you tap the indicator. Well, lunch is over and I can't think of anything else. ERS

Once that starts happening, what is the fix? I've got two which are a bit...sludgy... one a Starett, the other a Mitotoyo. Can't use 'em, can't sell 'em, and certainly can't toss 'em.

Dave Hinz wrote in news:3r7slrFi6vhvU1 @individual.net:

Either IsoPropol Alcohol, or Acetone will take care of the problem. Be sure to use some 3 in 1 oil on them after cleaning.

are you sure? that oil may be a bit too think I think it should be as light as possible

we the lighter fluid evaporates it will leave a light oil on the rod

Erik Litchy wrote in news:dimqjj01uv7 @enews2.newsguy.com:

hrm... Not been a problem so far with the 10,000 or so indicators we have in the plant...ymmv...

This was posted on RCM quite a while ago so you guys may be aware of this already, but if not check out this site:

All standard disclaimers apply, no connection, not even a customer, just like their website, weight not volume, blah, blah, blah...

Hope that helps.

-AL A.

Most commonly available isopropyl alcohol contains a fair amount of water, typically around 30%. I wouldn't use it for cleaning a precision tool.

Acetone will do the job if you are able to soak the part. But trying to apply acetone with a swab will be frustrating because the acetone evaporates so quickly, that you might not get enough saturation to effectively dissolve, dilute, and remove the gum. Methyl Ethyl Ketone (MEK) is a little better as it does not evaporate as quickly as acetone. But the biggest problem with using either acetone or MEK is that they are too aggressive: they will remove paint (e.g., the coloring in the engraved numbers on a micrometer) and they will damage plastic parts (e.g., the lens on your indicator). Also, acetone/MEK will strip the metal parts of ALL protective oils, so if you don't immediately re-oil (and cover every spot) you run the risk of rust (lack of barrier film and water displacement) and wear (lack of lubrication).

I use fresh, high-quality kerosene for removing gummed-up oil from tools and instruments. It evaporates very slowly, so you can apply a small amount with a swab and give it time to dissolve the gum/varnish. And because it's a mild solvent, you can soak parts if necessary. Either way, there's little risk of damaging any paint or plastic. And afterwards, the kerosene leaves a light (temporary) protective oily film behind, giving you time to properly oil the parts.

Regards, Michael

Why is that? I have a Mitutoyo DTI and find it to be a very fine instrument.

- Michael

DONT USE ALCOHOL TO CLEAN ANY METAL INSTRUMENT!!! Acohol contains water and rust follows when it is used. If you do clean the old oil out, don'r forget to put some new oil on all of the bearings or you will shortly have a dead instrument.

-- Why do penguins walk so far to get to their nesting grounds?

The cheap fix is to remove the old oil yourself and relubricate. However, this does mean that you have to disassemble the instrument all the way and that can be fun if you don't know how they go together. I use the LaBelle brand oils (model railroading lubricants) to lubricate my instruments. If you can't find a machinist type instrument repair place, a watch repair place can usually do the job. He's got the cleaning stuff as well as the oils to lubricate the instrument as well as all of the tools needed to do the work.

-- Why do penguins walk so far to get to their nesting grounds?

Really you need a microscope to really see what's going on in those.

Often the sore point is the 'mainspring' that preloads the mechanism. It's frequently held in place with a pin or a swaging that's tough to get apart, and back together, unless you can really see what's going on. One also needs to inspect the jewels and pivots carefully to be sure they're not damaged, and ultrasonic the parts in some solvent.

I like to re-lubricate the jewels with ATF actually. I use a 0.003 inch diameter piece of copper wire bent into a tiny loop at the end to hold just about the right amount of oil to hit the bearing with.

Jim

Then it is not isopropyl alcohol; it is 70 percent isopropyl alcohol, commonly sold as "rubbing alcohol". Isopropyl alcohol specifies just that, isopropyl alcohol, not a dilution thereof.

Jon

Excuse me for not being more precise. Allow me to re-phrase my statement: Most commonly available isopropyl alcohol SOLUTIONS contains a fair amount of water. Better?

I don't know what Anthony has available in his shop, but I'll wager that very few people here have ready access to 100% reagent-grade isopropyl alcohol. For many people, the recommendation to use "isopropyl alcohol" would simply imply that they go down to the drug store and buy a bottle of "Isopropyl Rubbing Alcohol" which would be a poor choice for cleaning precision instruments. That was the cogent point of my original post.

- Michael

Solutions of IPA are specified as to the percentage of alcohol contained within. In other words, looking at the label witll reveal the percentage of alcohol contained in the bottle, and allow the consumer to not have to guess at the contents.

As with many things, there is a tolerance within which the best results are achievd. That having been said, I doubt that reagent-grade solvents are required for this application, which is de-gooping a mechanism. Then again, I usually use white gas, so draw your own conclusions.

I would therefore assume that 99% IPA whould suffice for the intended usage. This is readily available online, and likely available locally as well - my local drugstore sells it by the pint for a couple bucks.. If you really do desire a higher purity, many electronics supply stores do sell 99.953% anhydrous IPA (GC 824 line), although it is a bit pricy.

Assuming the extremes of either 70 percent solution or reagent grade chemical is a bit too wide of a swing, don't you think?

Jon

How about using desalinated prune juice? See;

Better is ATF, non-gumming, long term stability is good.

Jim

On 15 Oct 2005 12:37:42 -0700, with neither quill nor qualm, jim rozen quickly quoth:

Ditto with MMO.

-------------------------------------------------------------

• * Humorous T-shirts Online
• Norm's Got Strings * Wondrous Website Design
• *
  formatting link