Author Topic: Another dial indicator repair - using ball bearings  (Read 735 times)

Offline Mcgyver

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Another dial indicator repair - using ball bearings
« on: September 25, 2019, 07:59:38 PM »
I ‘d mentioned this in Steamers thread and thought the process might be of interest…..I had this Helios tenths dial indicator that needed some help.  It was locked up, so, with some bergeoning (haha misspelled double entendre?) watchmakers skills I decided to have go at it.   Helios (German) stuff imo is of excellent quality and well worth restoring



On disassembly I found that several jewels were cracked.  Jewels are synthetic sapphires used as bearings (they are very hard and long wearing).  In a watch when the refer to say 17 jewels, this is what they are referring to.  The jewels have no gem value but simply are an indicator as to how much effort was put into making a quality product – as they do with an indicator



The jewels are held in what a watchmaker would call a “chaton”, a small bit of brass that is pressed into the watch's plate.  The top of the chaton is bevel so by apply some pressure with the right tool, the jewel can be sort of crimped into the chaton.

First task is to remove the chatons from the plate.  Here, everything has been cleaned using watchmaking equipment.  An L&R bath system and an ultrasonic cleaner for some parts.  I usually keep simple green degreaser solution in the ultrasonic cleaner and after removing most stuff run it through the L&R for a final clean.  The L&R with the right solutions does an amazing job.



Here’s a close up of a cracked jewel.



The breakthrough on this repair was the discovery of inexpensive miniature ball bearings.  New jewels are available, but after shipping the cost of a few would exceed the value of the indicator.  So it and a few similar projects sat until I read 2011 Horological Times article by Mark Butterworth, “Reducing Friction in Clock Bearings and Bushings.  There are precedents to this in horology (Hermle, Sattler) so I thought to give it a try - an indicator has a much easier life than a clock (based on duty cycle) so if it works in a clock maybe it will work here
 
Better still, there are seemingly good quality low cost miniature bearings available now, in the range of 2 for buck!

Here’s a shot of the 3 x 1 mm ball bearings I used, with a typical watch jewel and razor knife blade included for size comparison.  I think I bought a bag of 50 from that online retailed that used to be a great auction site 



I set up a lathe to make new chatons to fit the plate and bearing and went into production.   I have several indicators to look at as well as a travel so thought it worthwhile setting up a turret.  It was good experience, I made some tooling for the turret and ended up disassembling the turret and fixing a few things…so I partially justify the time as the shop the got better 





As a second op, I used a watchmakers lathe.  I snipped off the burr, gently countersunk the bore and filed a slight bevel (with a fine watchmaker’s file) on the OD to help start the press fit


Back with the staking tool, the chatons are pressed in



Pressing in the bearings is really delicate.  Too much of a press and you’ll damage the bearings.  Also use a stake that only puts pressure on the outer race.  In making the chatons I bevel them so the could be rubbed in (crimping the bearing) but ended up with a nice press that held them but didn’t damage them



I discovered what I thought was a depth issue as there was some binding of the wheels.  I pressed the chatons a little further in and things ran smoothly.  It turns out I hadn’t pressed the bearing to the bottom on the chaton, but at the time thought I must have made an error in their length

With this erroneous conclusion, and the chatons now proud of the other side, I needed to face off the now pressed further in chatons.  ( didn’t discover it was the bearing press depth until later) These watchmaker lathe faceplates make such a job just so easy to do.  With a very accurate centre through faceplate’s collet mount, work is easily centred






I used rodico in the bearing to keep it clean – it really did the job and caught all the swarf.



The pivots that go into the 1mm bores don’t need any attention but any going into plane bearings should be inspected and polished







Cleaned, here’s the completed indicator working to perfection.  3 jewels needed replacing. 





« Last Edit: September 25, 2019, 08:03:47 PM by Mcgyver »

Offline crueby

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Re: Another dial indicator repair - using ball bearings
« Reply #1 on: September 25, 2019, 08:07:13 PM »
Very interesting project - quite delicate work! Thanks for showing!

Online steamer

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Re: Another dial indicator repair - using ball bearings
« Reply #2 on: September 25, 2019, 09:16:58 PM »
Nicely done!    I have that tooling on my Levin.....I'm going to have to get into some of that....that looks like fun!

Dave
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Offline b.lindsey

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Re: Another dial indicator repair - using ball bearings
« Reply #3 on: September 26, 2019, 04:20:32 AM »
That is some amazing precision work. Great pictures of the process as well. Thanks for posting.

Bill

Offline mike mott

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Re: Another dial indicator repair - using ball bearings
« Reply #4 on: September 26, 2019, 05:29:15 AM »
Thanks for the great series of pictures and the explanation of the processes! I am envious of the lovely tooling that you are using as well.

Mike
If you can imagine it you can build it

Offline derekwarner

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Re: Another dial indicator repair - using ball bearings
« Reply #5 on: September 26, 2019, 07:49:36 AM »
Well Mcgyver......if all else fails in life  you will certainly get a well paying job as a photographer   

Brilliant presentation :ThumbsUp: ......many would not know [I certainly didn't] or understand the construction of a quality piece of machinery

The humble Helios Preisser [dial indicator?]

....I did notice and are a little confused with the accuracy nomination  :facepalm: of 1/10 000" on the dials front face

Derek  :cheers:
« Last Edit: September 26, 2019, 08:06:41 AM by derekwarner »
Derek Warner - Honorary Secretary [Retired]
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Offline stevehuckss396

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Re: Another dial indicator repair - using ball bearings
« Reply #6 on: September 26, 2019, 09:19:11 AM »


....I did notice and are a little confused with the accuracy nomination  :facepalm: of 1/10 000" on the dials front face

Derek  :cheers:

Each line is 1/10 of one thousand. full circle is 80 lines so a full spin is only 8 thousand of an inch
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Roger B

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Re: Another dial indicator repair - using ball bearings
« Reply #7 on: September 26, 2019, 09:45:10 AM »
Thank you for sharing that with us  :ThumbsUp:  :ThumbsUp: Watchmakers use some interesting tools  :) An excellent job and a good tool saved  :praise2:
Best regards

Roger

Offline derekwarner

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Re: Another dial indicator repair - using ball bearings
« Reply #8 on: September 26, 2019, 11:03:39 AM »
So Steve says ........"Each line is 1/10 of one thousand" ...... :facepalm: yes I understand this.....

So even at my  :old: age, am confident in adjusting work to 0.001" run out, but would not consider attempting a 0.0001" TIR  :Doh:

Derek
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Offline Chipswitheverything

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Re: Another dial indicator repair - using ball bearings
« Reply #9 on: September 26, 2019, 12:33:30 PM »
A very interesting and superb set of photos of an unusual model engineering restoration.  I have some watch making equipment, as my father had an interest in horology, but it's not often that tools for tiny watch componentry are able to play a part in the more familiar model engineering activity, so the repair that you have done is a nice slant on bringing the two together.   Dave

Offline Mcgyver

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Re: Another dial indicator repair - using ball bearings
« Reply #10 on: September 26, 2019, 01:42:50 PM »
Thanks for all the encouragement and kind words - much appreciated!
Mike