Thread: Etalon Dial Caliper-disection and resurrection.

Originally Posted by Ueee

Hi all,
A couple of weeks back i bought a .001" Etalon dial caliper dirt cheap. Ok so it has a bent thumbscrew...but it works. Thinking i had yet another bargain (its my year i tel ya!) i took it home in delight. I asked BT if he had any literature on them but alas he does not. No trouble, i found a pic of a nice one on ebay to see that it was missing the thumbwheel. I can live with that, and it gives me yet another project for one day....

Anyway, i went to use it for the fist time the other day and i noticed something fishy. It was not zeroing in the same spot every time it was closed. I thought maybe a bit of crap in the gears making them jump?

It took a few days but i built up the courage to pull it apart and have a look what was going on. Unlike the mity's, they have 2 driven gears, one to do the main body of work and one to remove any backlash from the system. The backlash gear is connected to a plastic disk, which in turn drives another plastic disk via a small tiny coil spring, ie the spring wrapped around the shaft and one end/leg engages on a lug on each disk.

The calipers had obviously been pulled apart at some stage, the preload on the spring lost and then put back together without being fixed.

There is a hole in each disk that seemed to be a handy place to insert a pin to hold the preload in place until the gears engaged the rack again. One turn of preload and half a dozen goes i managed to get it back together enough to check it......damn, not enough.....i ended up with 3 turns of load, at 2 there was still some minor inconsistencies in the readings, but 3 seemed to fix it. It is now back together and as smooth as, of course that took some trial and error too as i had to get the gears meshing with the rack just so too.

I tried to take plenty of pics but most of them are no good, its pretty hard to take good close ups with a phone.....

The price of all this fun? $15

Well done Ew.

How did you remove and reinstall the crystal? I should disembowel my busted Mitutoyo dial vernier.

BT

Your brave Nice repair I think my test caliper has the locking screw if you need pics although I sent mine to Switzerland for a cousin of mine to fix

Originally Posted by Anorak Bob

Well done Ew.

How did you remove and reinstall the crystal? I should disembowel my busted Mitutoyo dial vernier.

BT

Hi BT,

When i pulled the cover off the workings it pulled the needle off the shaft. The Crystal is plastic and simply a pressed in fit so i popped it out using a cotton tip through the needle hole.

Andre, I have one good screw to lock the head so i can copy it....i hope. I feel i may be going down the same road Stuart did with his Mity screw.

Ewan, If you can work out the pitch of the knurl I may have a wheel to suit. After Stuart's issues with finding the right size I got a selection so I would not be caught with the same issue.

Michael

Thanks for posting this Ewan. I have an eBay Tesa dial caliper with the same symptoms. I have been using it for fabrication/welding work because it repeats +/- 0.3 mm. Maybe now I can repair it and employ it properly.

Greg