test dial indicator movement

Hello,
First time poster here I have a Moore &Wright dial indicator, 8 jewels, 1mm movement, 1 micron resolution.
When I place the needle on the work to test, and rotate the work, if it's close to true, the dial will not move. But if I induce some vibration by running the lathe motor and try again, I get a true reading. Is this expected behaviour?
I have added some lubricant into the mechanism, but it changed nothing.
Here is a Dropbox link to a video showing what's happening: Dropbox - 20210225_182657.mp4 - Simplify your life

Thankyou
Joshua

I would have to guess stiction.

I've seen other instances where a toolmaker will do a continuous tap-tap-tap to overcome the tiny bit of stiction and have heard it referred to as "dithering". I don't know if that's a common term. In a similar vein, the place I last worked built fluid power test equipment that required calibrating pressure sensors with a dead weight tester. The stack of weights on the piston were spun to accomplish the same thing - elimination of any stiction error.

It's my understanding that indicator movements are designed to run "dry", without a lubricant. They use jeweled bearings, much like a mechanical watch and for similar reasons. The lubrication adds more friction in this case than it removes. And then there's the attracting/holding dust issue...

J.Bunn said:

Hello,
First time poster here I have a Moore &Wright dial indicator, 8 jewels, 1mm movement, 1 micron resolution.
When I place the needle on the work to test, and rotate the work, if it's close to true, the dial will not move. But if I induce some vibration by running the lathe motor and try again, I get a true reading. Is this expected behaviour?
I have added some lubricant into the mechanism, but it changed nothing.
Here is a Dropbox link to a video showing what's happening: Dropbox - 20210225_182657.mp4 - Simplify your life

Thankyou
Joshua

Click to expand...

Age-old challenge, as already mentioned. SOME makers had "bad spells" wherein a suboptimal design choice made them borderline notorious for it. Federal for example.

Modern metrology might use radiant energy, no longer be ABLE to even have the problem.

"Dithering" and taking multiple reading is simply wot you HAVE do in an all-manual Old Skewl, old INSTRUMENT environment. The goods - and any lubes - are a long way from new.

Some Old Skewl mechanicals are waaay better than others. Moore & Wright is not a "first tier" maker, (Hilger & Watts very much WERE) sooo

Might want to keep an eye out for used-but-good:

Hamilton/Dorsey, Tesa/Weiler, B&S, Interapid, Compac, P&W (Dorsey for older, 2d tier Japanese if newer), Georg Mahr, and Mitutoyo.

I happen to have an aversion to "batteries", so newer "electronic" goods, a Mahr "millimess" 20-millionths and "the usual" electric calipers is all I have bothered with.

MANY other PM members know a LOT more.

Bottom line is even if your "backup" DI can only be a used one bought cheaply, a backup you can also compare between and among you should surely have.

Even a one-legged man usually owns more than one shoe. Or would if he could afford it.

Might as well be one of the Grand-Old - and most-often SWISS - names. The DI. Not the shoe.

Thankyou all for your replies.
I thought it was getting a little old, and had had some knocks, so I went out and bought a new one this morning. Exact same product, I tested it tonight and it did the exact same thing... didn't move. I was gobsmacked.
I think ill return it and buy a test (lever) indicator instead from Mitutoyo.

Josh

Milland said:

It's my understanding that indicator movements are designed to run "dry", without a lubricant. They use jeweled bearings, much like a mechanical watch and for similar reasons. .

Click to expand...

agreed, introducing lubricant was a mistake. I've fixed a fair number of these, at least for the ones I've seen, the problems are 2% a drop has buggered up the teeth on the rack, 3% a cracked jewel and 95% dried lubricant gumming up the return spring (like a watch hair spring) and the bearings. Yesterdays one, a mitutoyo, was still sticky after ultrasonic cleaning, but after a minute in L&R watch cleaner then rinse it is perfect.(that L&R cleaning an rinse are amazing)

Watches are oiled of course, but the devil is in the details on why imo indicators should not be. A basic and key skill to watchmaking is knowing how to oil - putting just the right amount on. Its stays in the right location by surface tension but if too much is applied, it runs off. Cleaning out the old and re oiling needs to be done every few years. As we don''t take indicators in for cleaning and oiling every few years (it would hardly be cost effective), this important step doesn't happen and any lube just collects dust (aides in wear), dries up and often makes the indicator sticky or non functional. As our indicators have a duty cycle an infinitesimal fraction of a watch's, I don't think lubrication is necessary for longevity as it is with a watch. As it is, if not dropped, non-lubricated indicators seem to work well for decades if not lifetimes.

you can sometimes get rid of the stickiness by taking the back off and squirting in some isopropyl alcohol, but it rarely lasts. (Caution on using anything stronger, it might affect the ink/paint on the dial. ) If that's the issue, really it needs to be disassembled and properly cleaned

J.Bunn said:

Thankyou all for your replies.
I thought it was getting a little old, and had had some knocks, so I went out and bought a new one this morning. Exact same product, I tested it tonight and it did the exact same thing... didn't move. I was gobsmacked.
I think ill return it and buy a test (lever) indicator instead from Mitutoyo.

Josh

Click to expand...

I MIGHT have about .. TWO dozen? If I count the disposable "kleenex" Chinese ones used where damage is likely and I don't NEED much, (daily drivers, shop-floor).

But the only OTHER ones I have more than two of the same brand are Dorsey (the Hamilton inheritor) and Tesa.

Variety is good for cross-checking (the 20 millionths Mahr vs the ten-Millionths Hamilton, for example) partly because... not being a "bizness" "calibration" services nor overhaul by a super-pro, such as Long Island Indicator, is not ordinarily in MY budget.

The Hamilton/Dorsey & P&W-rebranded Hamilton/Dorsey ones are ALL "back plunger" type, whereas the Swiss goods - and the lone 1930's or older Starrett, "Last word" - are all lever-tip of one form or another.

I suspect this all got started "back in the day" when guys collected GF's panties?

At least the DI/DTI collection takes up less space.

2CW