Stuck Dial Gauge

Opened a boxed dial indicator tonight, been in the box unused for unknown number of years.

Problem is the movement is very stiff to move and does not spring back to the rest, stop ? position so question is how can I release the mechanism and have myself a usable instrument?

It was stored in a dry drawer in a cardboard box and there is no sign of corrosion anywhere on the casing. All advice welcome

Edited By Dod on 24/03/2016 23:51:37

Take the back off and look inside, before you make any further decision ... The mechanisnm sometimes corrodes worse than the case.

MichaelG.

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Try a few drops of petrol on the plunger where it goes in and out. It might just be gummed up with age.

Don't put oil or WD40 etc on the plunger as it will gum up the plunger and make it more sticky.

The old Mitutoyo repair manuals recommend gasoline only on the plunger where it enters the sleeve/body.

Yes Hopper is correct, sticky plunger due to the oil turning to varnish. My old Mercer DTI does that if not used for a long time. I put a few drops of lacquer thinners or benzene on the plunger and hold it so the liquid runs into the plunger bush. A few strokes pushing it in and pulling it out sorts out the problem, until the next time! A drop of paraffin with 10% ATF dissolved in it is a good lubricant.

Hello John,

What please is ATF?

Regards

Brian

Automatic transmission fluid.

David

Thanks folks, all advice sounds good to me so will get some petrol type gasoline today and try it when I get some "quality me time" in shed.

My thought is using ATF, thankfully explained, is that never having need to buy the stuff a one litre/liter, (depends wherever you read this) seems a bit of overkill so would there be an alternative to ATF likely to be in a shed

32 grade hydraulic oil often used in gearhead lathes.

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Oh well ... What the eye doesn't see the heart doesn't grieve over.

MichaelG.

Hi Brian,

Yes ATF is the stuff used in power steering and automatic gear boxes in automobiles. And there are several grades of ATF, mineral oil based and true synthetic. I keep it not because I have car which needs it but for pumped cooling systems on our radio telescopes. Mixed 10% with paraffin it lubricates the high pressure scroll pumps inner moving parts well which use the paraffin as a thermal transfer fluid.

Lovely stuff and it withstands up to +400C temperatures! Even makes a good substitute for steam oil in some applications. Readily available in small quantities from motor factors or garages.

Thank you John for the helpful explanation with likely sourcing and David also for the quick response

Brian

I've heard two different recommendations for dial gauge lubrication:

1) Don't use any lubricant at all.

2) Use sewing machine type oil VERY sparingly.

Not sure which is right!

Dip a cotton bud in to your cars power steering tank, should be all you need.

I drive a Citroen - would LHM do?

Best regards,

Swarf, Mostly!

Starrett Tool and Instrument Oil could probably be used for the lubricant.

Try GT85 it removes old oil and debris an lease a film of PTFE (it is not at all like WD40). I have got several stuck DTIs working perfectly using GT85 and some TLC.

LHM (Liquide Huile Minerale) Is straight 30 mineral oil with a green colour in it. Bit too thick for a dial gauge! It is probably the plunger stuck as said above, so a solvent is the best idea, backed up perhaps by the tiniest amount of 3in1 which should be wiped off after it has freed up to leave just the merest film of lubricant on the plunger. the pivots and gears generally require no lube whatever. Have a look with a loupe to make sure you haven't got any bent gear teeth or other (drop) type damage.

Phil

Oil from a sweaty brow is all that should be used, as has been said do not go near it with any oil, it will gum up at the drop of a hat. Dust and other air born particles stick to it and exacerbate the problem.

Near 4 weeks have passed and with paraffin, petrol, methylated spirit and liquid butane all tried and had the gauge in a sealed tin with the back off for a week over paraffin fumes the gauge moves stiffly but it still will not move under the return spring power.

No corrosion to be seen and no evidence of damage using when viewed with a big magnifying glass so any more ideas before dismantling to look for further stickiness.

You seem to have tried everything reasonable ... short of dismantling it and cleaning it like a watch. 

My guess is that either the pivot holes are gummed-up with oxidised oil, or the plunger is slightly bent.

Can you show us some detail photos of the mechanism ?

MichaelG.

Edited By Michael Gilligan on 15/04/2016 22:04:07