Hi if you search on YouTube I very quickly found 4 clips of people making repairs to various makes of dial indicators.

This might help you understand how they are dismantled

HTH

Chris

The vital thing is not to lubricate the stem in anyway at all. It must work dry. Try wiping it with a tissue moistened with a little solvent. If you take the back off you can clean the bit of the stem inside with a cotton bud. Make sure that all traces of the solvent have evaporated or have been wiped away. The stem should now move freely. This advice was given to me many years ago by an old employee of Mercer and it has always worked for me. Normally the actual mechanism will not require any attention. Many people try to cure a stick stem be applying oil with the result that matters are made worse.

I repaired many when I did an 18 mths stint in the standards room at Ferranti a long time ago.

From memory ( a long time ago ).

As stated you need a very clean, dry, score free spindle using solvents.

The only special tools other than good small screwdriver sets needed to dismantle are a couple of good sets of finger lifters. A small set for the main finger and a very small set for the revolution counter finger. These are literally miniature types of tyre levers with a small groove cut in to clear the finger spindle, 2 per set.

Depending on indicator model basic dismantle starts:

Remove Back.

Remove plastic rotating main screen either clips or screws.

Carefully lift each finger using equal pressure with lifters at 180 deg under each and lift of dial.

This usually reveals a couple of screws on the outer edge of the main gear train assembly that hold it to the indicator assembly. They allow rotational adjustment of the gear train assembly to mesh the main first contact gear with the linear spindle rack gear. Remove these screws and the gear train can be removed and further dismantling necessary of the gears and springs.

Remove the end fittings from the spindle and slide out.

Do all the cleaning and score removal necessary, check for free smooth movement in housing.

Reassembly is a reversal of above but: when you mesh the main small gear with the rack you will need to reset the preload on the main spring as follows.

Rotate the gear train so there is no mesh with spindle keeping the adjusting/locking screws lightly nipped. Very lightly refit the larger finger with the lightest tap just sufficient to rotate the gear train.

Wind about 4 complete revs to tighten the main spring and whilst then holding to prevent unwinding rotate the gear train assembly to mesh with the spindle and tighten the two rotational adjusting/securing screws. There should be minimal play twixt spindle and gear.

At this stage you need to check its operation. The spindle to be clean and smooth operation. The main finger should move promptly and cleanly and return to its zero point. You may need to play with the preload revs and meshing to get this right.

Remove finger.

Refit dial. Refit fingers by lightly tapping back down with a good small diameter flat ended punch, taking care not to bend the spindles.

Reassemble front.

Reassemble back.

No doubt there are others who may be able to correct if needed.

No real help, because I've never got around to fixing it, but; here are a few pictures to show how nasty they can get inside … This one felt just a little sticky.

MichaelG.

Edited By Michael Gilligan on 16/06/2015 22:54:16

Acetone can attack some paints and plastics as well.

I've bought IPA in half-litre cans from CPC.

I believe the video cassette recorder head cleaner fluid that Tandy used to sell in 60 ml plastic bottles was also IPA.

Best regards,

Swarf, Mostly!

I've an old Mitutoyo service sheet that instructs to clean and lube the stem with petrol only and to never put oil on the stem. I have found it works ok on old dial gauges (One of which just happens to be an old .0001" Mercer that still is my precision "go to" in the workshop.)

Edited By Hopper on 17/06/2015 12:50:00