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DIY dial indicator repair

ironhoarder

Cast Iron
Joined
Oct 9, 2005
Location
Waterford, VA USA
I have a drawer full of various dial test indicators that are in various states of disrepair. Time to get some of them going!

I picked up at an auction recently a nice, complete starrett last word set and a federal DTI very cheaply because both were missing the crystals- otherwise fine. I found that I can buy crystals from Long Island Indicator repair, and a crystal press is abut $20 on ebay. Sounds like a plan.

I have some others that basically work, but are either sluggish (don't like to return to zero always) or sticky. It sounds like in both cases, they need cleaning and lubing. This is the heart of my question.

Can anybody offer suggestions on how to properly clean and lube a delicate mechanism like this? It is not worth the money to have them repaired by a shop- I want to try it myself. I thing it is an issue of the right materials and techniques.

Suggestions?
 
Do not use WD40!

I ~believe~ that you might try to use ATF.
But you might want to do a search before you do that.
Pete
 
Ironhoarder;

Look on amazon, or bookfinder4u for a copy of "repair of dial indicators and calipers by Michael T. Yamamoto the ISBN # is 0-9679279-4-3.

It has all the iformation you will need to start repairing indicators. Starrett parts are available from them at 1-800-784-2887 you can use a credit card for orders under $25.00.

It is best to use clock or watch cleaning solutions if you can find them. They don't hurt or gum up the works.

As for oil I use clock oil purchased from a clock repair shop.

If you have steady nerves and patience you can repair most indicators but the cheaper ones aren't worth much time.

Good luck!
 
I just take them apart and clean them really well. I'll rub a little 3 in 1 on my fingers prior to reassembly, and residual residue from that seems to be enough.

As for cleaning, a sewing needle cleans the gear racks and gear teeth nicely. Just use whatever solvent and paper towels for the rest. It's tedious, but the biggest culprit seems to be gunk in the gear racks and teeth. I do EVERY tooth individually.

I sit and work on them on a nice clean piece of white formica covered plywood in front of the boob tube. Easy to keep track of all the small parts, I'm not in a hurry, been very successful.

Just like you, I started with a couple dial indicators that were CHEAP off of ebay, just for the experience. I now have a nice Mit set and a really nice B&S for $5 ea.

Fixed a number of others instruments since.

Tools
 
Ironhoarder, your post was timely as I just picked up a DI at an estate sale and it's missing a crystal. Thanks for the link.
I used gun oil on this one, working it past the plunger in small amounts. Seems to have fixed the sticking, after a bit got into the works. I would prefer sewing machine oil if clock oil is not handy.
I'd also like to open this one and clean it out, but I admit I'm a bit timid.
 
FWIW, the various times I've had problems with a typical 1" travel indicator getting "sticky" has been one of two things:
The quill gets gummed up with dried machine coolant. A bit of WD40 is all it takes to loosen that up, with a simple external application and wipedown.

The other common cause of a sticky needle problem seems to be due to a loosening of the screws holding the face onto the body. This seems to then lead to the pinion being forced too tightly into mesh with the quill, and then it sticks. Sometimes it can be a bit of work to expose those screwheads. But, I've never really had an indicator get what I would call dirty inside, so I've never really bothered with a complete overhaul.
 
I recall a newsgroup post that quoted Starrett as suggesting that only clean mineral spirits and NOTHING else, be used.

I've used very light instrument oil and then, using the torn edge of a piece of paper, wicked away the excess.

Den
 
I would agree they stay clean inside. However, on one I had, the stem was bent, so had to disassemble the thing to correct the problem. Also, dial calipers WILL get dirty inside, so then you've go to just go in!

I was kinda intimidated at first, but turns out, they're no different than anything else. Only you don't smash fingernails, skin your knuckles or get all sorts of nasties falling in your face as you work. Kinda gentlemanly repair work if you ask me.

Tools

A little magnifying glass ain't a bad idea!
 
Was going to tell ever body about how I cut crystals , I use welding lens 4 1/2 x 4 1/2 clear
Make up a hole saw out of scrap I used HR Hand cut the teeth by hand . Cut a hole in the side of your saw (so you push out the lens) Use a drill press slow speed. My cost is about $3 I am too dumb to post a picture of the saw
 
I found the Yamamoto book at OKDPM and nowhere else, so I ordered it.

Interesting idea about mineral spirits- that should serve as a cleaner and a very fine lube as well.

I just turned 50 and my vision on close-up work is pretty bad- so a jewelers magnifier is an absolute must for this sort of thing.

I considered cutting my own crystals for about 30 seconds until I realized that a domed shape is needed for many DTI's I have. And since you can buy the exact right crystal from long island indicator for about $7 and $20 for a crystal press, this seems like a no brainer to me. Especially since I have at least 5 crystals to replace.

While we are on the subject...can anybody suggest any good references on various mountings and uses of indicators in machining operations? Many times it seems that when I finally figure out a way to mount an indicator to tell me what I want, I can no longer see the dial.

Or, there is no suitable surface onto which I can mount the mag base, etc.

Thanks for the suggestions, all.
 
I do use ATF when rebuilding indicators to
lube them. It's a non-gumming oil that is very
stable, and about the correct viscosity.

However the pivots only need a tiny amount of
oil. I use a small diameter wire (about ten
mils or so) bent into a tiny loop at the end
with a fine pair of tweezers, to pick up a
tiny amount of oil and deliver it to the
pivot and jewel. The amount is correct when
there is a small meniscus between the pivot
and jewel. It's not much.

I've never had much luck rebuilding dial
indicators unless I take them all apart and
clean them. I prefer to use alcohol for the
parts that can stand it, in an ultrasonic cleaner.
Basically this means stripping all the working
parts from the indicator so they can immersed.

Things like the painted dial, painted case,
etc, cannot take any solvent.

Possibly the toughest part to explain is
removing the mainspring that preloads the
gear train. Often it have its end pegged in
place with a small brass pin or peg to fix
the end. Then upon reassembly the geartrain
has to be preloaded or wound up so as to
eliminate backlash in the movement.

This is a pretty touchy operation and it is
made a *lot* easier if one has access to a good
binocular microscope to work under.

Dial indicator crystals can be made by a method
that an RCM regular suggested, I honestly forget
his name but he deserves a large credit here
when remember who it was, because I've made
many replacement crystals using his technique.

Basically you just figure the approximate
diameter, and the approximate dome height.
Then put a piece of soft pine in the four jaw
chuck, and turn a roughly spherical depression
in the wood that is about the desired diameter,
and go in about the height of the dome you want.

Then screw a piece of thin plexiglass to the
wood, centered roughly over the depression.
Apply heat with a heat gun, and the plastic
will sag into the depression. You can help
it along if you want, apply pressure with a
rag by hand.

Once it cools down, trepann out the exact size
crystal you want, based on the ID of the rim
of the indicator. You want it to be oversize
by 10 or 20 thou so it snaps into place, the
profile of the rim also matters to some degree.

This may have been Ted Edwards idea, actually.

Jim
 
BTW, the watch types use an oiler of fine wire with an "arrowhead" formed on the end. I tried one, and they do pick up and deliver a more controlled amount than the cat whisker I used to use, or a fine wire.

There are apparently various sizes of genuine watchmaker oilers. They pick up different amounts of oil.
 
A single, straight wire will be pretty much
unpredictable, the oil wil form beads along
the length and you may get more than one
sliding down onto the destination!

I like having a tiny loop at the end, for a
given viscosity oil it seems to be repeatable.

At work I've been using 0.003 inch diameter
plain copper wire.

Jim
 
Sorry to revive a old thread but I just ordered the book (from Ebay cant find it anywhere else) on dial indicator repair thanks DJones for posting it! Been interested on how to disassemble, repair or maintain and reassemble them since I got mine.


Hopefully after reading that book to get the infromation I'm going to be able to try and eventually fix a dial indicator, and after that quite possibly get decent at it. :D

Dimitri
 
used indicators

I see people think a crystal press is the only way to put on a crystal you can get a (crystal lift ) its a watch makers tool.
And as for old indicators check out WWW. Indicator repair site.com
They will pay cash for broken indicators.
 
I have a drawer full of various dial test indicators that are in various states of disrepair. Time to get some of them going!

I picked up at an auction recently a nice, complete starrett last word set and a federal DTI very cheaply because both were missing the crystals- otherwise fine. I found that I can buy crystals from Long Island Indicator repair, and a crystal press is abut $20 on ebay. Sounds like a plan.

I have some others that basically work, but are either sluggish (don't like to return to zero always) or sticky. It sounds like in both cases, they need cleaning and lubing. This is the heart of my question.

Can anybody offer suggestions on how to properly clean and lube a delicate mechanism like this? It is not worth the money to have them repaired by a shop- I want to try it myself. I thing it is an issue of the right materials and techniques.

Suggestions?
Old thread here but maybe someone will see this. I have seen somewhere that mineral spirits are good and do not leave a residue. I think I saw it on the Long Island Indicator repair website. But you should avoid getting it into the crystal and readout face. I have used 3-in-1 brand penetrant with success but only on the stem of a last word avoiding getting any in the dial. That is only because I didn't have any mineral spirits.
 
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