Cleaning dial gauges

Use a soft cloth with soapy water on to get the thick off, then use meths to clean the rest of it. Don't use any oil on the spindle and if you need to unstick it use plenty of meths. If you don't have meths use white spirit. Oil attracts all sorts of nasty dust and metal shavings etc which will kill a DTI in no time. Try to avoid total immersion as it will be hard to get them 100% dry afterwards. I don't know of any DTI which is waterproof. Though there probably are some out there which I have not come across. Always try to keep them clean and dry and don't drop them ;-)

Andy

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Hi Tim, DTIs are quite fun to pull apart and repair. No special tools are needed save watchmakers screwdrivers tweezers and a means of pulling off the pointer. If you go to one of the Watch and Clock fairs, you should be able to get the bits and pieces including a glass., you will need to know the size first. Failing W&C fair Fleabay must have something. Re. cleaning, were not talking Rolex so lint free rag or tissues and a solvent will work wonders, but no oil please. Although watch oil on internal pivots should do little harm, if correctly applied ie V little. Ned Ludd

I reckon these will need *internal* cleaning, hence my suggestion of the ultrasonic bath. Is there any fundamental reason why I shouldn't take the backs off and put them in a suitable medium in the ultrasonic bath, provided they're thoroughly dried afterwards?

Thanks Tim

Take the back off, normally 3 or 4 screws, don't worry it won't 'explode' out at you, unless it is well shagged and some numbty has packed it all back inside. Have a look, if you still think they need a clean then have a go with the worst one first, give it a clean in your ultrasonic bath and give it a good dry followed by some time on a radiator or in an airing cupboard or somewhere warm and dry but not too hot as some internal parts may be plastic and might not last in an oven or some other great heat source. Once dry lightly lubricate with the lightest oil you can get your hands on. DTI's do not like thick oils, ideally you should be looking at something lighter than WD40 but at a push that would be ok. Squirt some into a clean dish then apply to the gears and gear pivots using a cocktail stick or matchstick. Oiling must be kept to an absolute minimum.

If you decide to dismantle them keep the bits separated if they are different makes. A good pointer removal tool can be fashioned out of an old Alan key. I made one years ago from a 4mm Alan key with a bit of careful use of an off hand grinder, a file and a hacksaw. Trim the small end of the key to about 13mm then thin the outside edge of the short end with the grinder to about half its thickness, use a file to thin the inside face so there is about 1mm thickness, then use a hacksaw to carefully put a slot down the middle to form a sort of 2 pronged fork, I still use mine on a regular basis still.

At the end of the day its your call, do what you think is right, you got the DTI's for nothing so what have you to loose? They are not that expensive to buy if you really want one. It's a shame you didn't post this a couple of months back as we scrapped off several large box full's of broken clocks at work. We use them in modular gauges and they get broken almost on a daily basis.

Out of curiosity what make are they? I might be able to get a used glass for you?

Andy

to

Hi Tim, If you must ultrasonic them, might I suggest you remove the face first. The "paint" surface is often dry and crumbly and will not stand much abuse. Ned Ludd

Thanks for that. They're both Mercer, fairly modern metric, the one with the missing glass is the 'small' size, 38mm glass, type 185. They came in a job lot which I wanted for a couple of the other items so they don't owe me much, but if I can get them useable with a minimum of time & effort expended so much the better. I don't plan to spend hours dismantling the 'works' and losing bits

Cheers Tim

I know nothing about DTIs, but as a clock repairer (and at one time a chemist) I am used to small mechanisms and can assure you that WD40 is almost the worst thing you could use. Its feeble lubricating power relies solely on the solvent it contains, which once it has evaporated, leaves a sticky gummy residue which will leave your instrument in worse condition than it is now.

I suggest you use the lightest oil oil you can find (Mobil 1 synthetic motor oil is good) and apply the tiniest amount only to the pivots. Leave the gear teeth absolutely dry.

Cliff Coggin.

What, then, of White Spirit and Meths as cleaning agents?

Do they leave a residue?

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What is the trick to moving the glass from dial gauges? I have nice Mitutoyo imperial dial gauge which has a slightly bent needle. I would love to straighten it, but I can't see how to remove the front bezel and glass.

Mike

White spirit will be fine. Meths will not dissolve old oil or grease.

Cliff.

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What is the difference between white spirit and mineral turpentine, as I don't seem to be able to get white spirit.

Thanks Kevin

What about it?

Cliff.

I suspect mineral terpentine is just another name for white spirit, which itself is an oil-derived substitute for natural terpentine. (In fact I recall it being called "terps substitute" when I was young.)

Cliff.

White spirit and Turps Sub used to be two slightly different products, IIRC White Spirit was slightly more refined (and thus less likely to leave a deposit), white spirit was OK for thinning paint but Turps was best restricted to brush cleaning etc. I think you can still buy solvents under both names but suspect it's the same thing with different labels.

Tim

I have a supply of 100% pure Isopropyl Alcohol, bought 2 x 1 gallon containers from my local chemical supply warehouse about 5 years ago.

I use this for all cleaning and (final) degreasing as it evaporates off and leaves absolutely no residue. I also use for machining Aluminium as I find it perfect for the nsame reasons as above. No residue, stops chip welding, and it has an evaporative cooling effect.

Not that expensive either from what I recall, and after 5 years I still have around a litre or so of it left.

Peter

Thanks for that; I have a s/h Mercer G.303 dial indicator,

(which I used here:

)

But it's a little sticky. Despite my simple diagram on the website, I *actually* did the measurement by sloping the plane slightly, first "nose up" then "nose down", and tracking the dial gauge in both directions to minimise sticky hysteresis errors.

I didn't want to go into all that on a "simple" website.

But now I think I may have a look inside the dial indicator.

Wish me luck!

BugBear

Cliff I would use anything but WD40 in this instance. The original poster may not have access to anything but WD? I don't know? I said "at a push use WD"... Even a drop of vegetable oil from the kitchen would be better than WD. He plans on using his Aldi ultrasonic cleansing bath to clean these DTI's, it will be totally void of any lubricant, a drop of anything on the gears will certainly help in this instance surely?

I'm used to an environment (main work job) where spending anything more than

20minutes repairing a DTI is less than cost effective. As far as I am concerned paying £20-£30 for a brand new DTI is worth every penny spent, no sticking, clean, all screws there and stylus intact.

Andy

As I've said, I'm not planning to put a lot of time into these, which is why the ultrasonic bath came to mind as a quick way to clean them up. They don't owe me much, and my time is limited, but it would be a shame to just bin them without some sort of attempt to make them serviceable.

Thanks to all for suggestions Tim