Detailed Repair or Restoration Manual for a Mikron Watchmaker’s Lathe – How to Repair Headstock Bearings

[Will RobertsonParticipant @willrobertson16447]

I've just become the very happy owner of a very beautiful Watchmaker's lathe made by Mikron in Biel, Switzerland – Mikron were better known for their hobbing and milling machines than for their lathes but were one of the manufacturers who – together with Schaublin – pioneered modular precision lathe systems – I think some of the Mikron T90 lathes made it over from Switzerland to the UK – there's some more information about them here:

http://www.lathes.co.uk/mikron/

and here

Mikron T90 Lathe

Before buying the lathe I tried the headstock bearings and they were in fairly terrible condition with a bit over 1 mm wobble. Overall, the lathe has had a very hard life and there's wobble on the saddle that I'll also need to address. I know that Mikron made this lathe with the intention of the headstock bearings being adjustable, repairable and finally replaceable but I'm having difficulty finding a manual with details and specifications of how to adjust – and if necessary replace – the bearings. I've got access to high quality bronze stock to make new bearings if needed, a larger lathe and a mill but I didn't want to attempt to adjust or replace the bearings until I'd studied the details.

Does anyone know where I could get a suitable manual or instructions for replacing the headstock bearings and restoring the lathe in general? (I can read English, French, German and Italian.)
Will

[Will RobertsonParticipant @willrobertson16447]

[Michael GilliganParticipant @michaelgilligan61133]

Lucky Man

Sorry, can’t help with a manual now … but happy to have a dig around.

I am guessing that bearings may be double cones each end … if so, you might have a tricky job on your hands !!

MichaelG.

.

Edit: __ Please ignore the drivel I spouted above:

Edited By Michael Gilligan on 05/03/2023 16:27:27

[Michael GilliganParticipant @michaelgilligan61133]

I thought I remembered seeing something about the bearings … check the post by Kaspar on this page:

**LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=138694&p=2

MichaelG.

[Harry WilkesParticipant @harrywilkes58467]

Michael

Who need a search tabs when we have you

H

[Will RobertsonParticipant @willrobertson16447]

Posted by Michael Gilligan on 05/03/2023 16:37:32:

I thought I remembered seeing something about the bearings … check the post by Kaspar on this page:

**LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=138694&p=2

MichaelG.

Thank you very much Michael! Just scanned over that and it looks very useful – I'll re-read it in detail. I'd seen the "F75" in the title and thought that it was about one of the Mikron milling machines (milling machine is "Fräsmaschine" or "Fräs" in German and Swiss German).

[Dave HalfordParticipant @davehalford22513]

Looks like a T&LM style split cone head stock though the bed is very different. You edge them tighter as in 'loosen the back and tighten the front in small amounts with a C spanner till the play goes. It's very likely the bearings are fine, but they have been loosened to mess with the belt .

If there are felts in the bottom slot they are best left in place, they swell up and will not go back.

[Will RobertsonParticipant @willrobertson16447]

Posted by Dave Halford on 05/03/2023 21:09:28:

Looks like a T&LM style split cone head stock though the bed is very different. You edge them tighter as in 'loosen the back and tighten the front in small amounts with a C spanner till the play goes. It's very likely the bearings are fine, but they have been loosened to mess with the belt .

If there are felts in the bottom slot they are best left in place, they swell up and will not go back.

Hi Dave,

Thank you very much.

>Looks like a T&LM style split cone head stock

Does there tend to be there more information available about T&LM lathes than about Mikron lathes?

>You edge them tighter as in 'loosen the back and tighten the front in small amounts with a C spanner till the play goes.

Thank you very much – that's an enormous help – I hadn't been able to find any documentation on it so it's enormously valuable to know that that's how to adjust the bearings. Is it reasonable for me to expect to be able to get rid of c. 1 mm radial play by adjustment alone? Should I attempt to clean out the bearings with solvent then compressed air to remove old oil and other debris then lubricate with fresh lubricating oil before adjusting?

I don't even know at the moment what lubricating oil specification would be suitable for bearings like this.

>It's very likely the bearings are fine, but they have been loosened to mess with the belt

Thank you very much. I don't fully understand "to mess with the belt" – unfortunately my generation were taught CNC and got no training in belt driven equipment. The motor and belt drive hardware that would have originally powered the lathe was all long gone when I bought it so I'm planning – without making any modifications that damage this historically significant lathe – to power it from a modern variable frequency motor and variable frequency drive that I have here or to buy a modern geared stepper motor to power it – hopefully if I get it right the geared stepper motor would have the advantage of allowing the lathe to be used as a divider and simple machining centre as well as a traditional lathe.

Thank you very much again for your help!

Will

[Will RobertsonParticipant @willrobertson16447]

I was able to collect the lathe and get a micrometer on the headstock and the radial play on the headstock bearing that it measured was 0.25 mm – not the "a bit over 1 mm" that I'd guesstimated by hand – apologies for my grossly incorrect manual guesstimate on that. 🙈

[Dave HalfordParticipant @davehalford22513]

Posted by Will Robertson on 06/03/2023 10:52:07:

Posted by Dave Halford on 05/03/2023 21:09:28:

Looks like a T&LM style split cone head stock though the bed is very different. You edge them tighter as in 'loosen the back and tighten the front in small amounts with a C spanner till the play goes. It's very likely the bearings are fine, but they have been loosened to mess with the belt .

If there are felts in the bottom slot they are best left in place, they swell up and will not go back.

Hi Dave,

Thank you very much.

>Looks like a T&LM style split cone head stock

Does there tend to be there more information available about T&LM lathes than about Mikron lathes?

>You edge them tighter as in 'loosen the back and tighten the front in small amounts with a C spanner till the play goes.

Thank you very much – that's an enormous help – I hadn't been able to find any documentation on it so it's enormously valuable to know that that's how to adjust the bearings. Is it reasonable for me to expect to be able to get rid of c. 1 mm radial play by adjustment alone? Should I attempt to clean out the bearings with solvent then compressed air to remove old oil and other debris then lubricate with fresh lubricating oil before adjusting?

I don't even know at the moment what lubricating oil specification would be suitable for bearings like this.

>It's very likely the bearings are fine, but they have been loosened to mess with the belt

Thank you very much. I don't fully understand "to mess with the belt" – unfortunately my generation were taught CNC and got no training in belt driven equipment. The motor and belt drive hardware that would have originally powered the lathe was all long gone when I bought it so I'm planning – without making any modifications that damage this historically significant lathe – to power it from a modern variable frequency motor and variable frequency drive that I have here or to buy a modern geared stepper motor to power it – hopefully if I get it right the geared stepper motor would have the advantage of allowing the lathe to be used as a divider and simple machining centre as well as a traditional lathe.

Thank you very much again for your help!

Will

T&LM info here just for interest.

The T&LM does not have wicks, the Mikron does so be careful not to ruin them. Oilers like these seem to stay clean

[Will RobertsonParticipant @willrobertson16447]

T&LM info here just for interest.

The T&LM does not have wicks, the Mikron does so be careful not to ruin them. Oilers like these seem to stay clean

Thank you very much! I can see the similarities with the T & L.M. headstock now.

My Mikron seems to have very fine metal tubes to syphon the oil from the oilers down into the bearings rather than fiber wicks. Are those fine metal tubes referred to as wicks as well?

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