Detailed Repair Manual for a Mikron Watchmaker's Lathe - How to Repair Bearings

[Will Robertson]

Does anyone know where I could get a detailed repair manual for a Mikron lathe?

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 pioneered modular precision lathe systems - there's some more information about them here:

Mikron Lathes

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, 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? (I can read English, French, German and Italian.)

 

[dalmatiangirl61]

I've yet to find a detailed repair manual for any lathe, if you are lucky you might find some exploded drawings. Looks like a fairly simple machine, dig in, take pics if needed.

 

[Will Robertson]

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 "bit over 1 mm" that I'd guesstimated by hand.

 

[reggie_obe]

Did you contact Mikron?
I'd do that before expecting a random forum member to have detailed info.

 

[Will Robertson]

Did you contact Mikron?
I'd do that before expecting a random forum member to have detailed info.

Thanks - I've just emailed them - will see how they reply.

 

[Will Robertson]

Did you contact Mikron?
I'd do that before expecting a random forum member to have detailed info.

Just got the reply from Mikron - "too old" ?! - it's only 80.

"Sorry to inform you that for this machine type we don’t have any documentation, manual and/or spare parts available as really too old."

 

[Peter from Holland]

https://passion-usinages.forumgratuit.org/t1843-mikron-t90

Here you can download a cataloge But not a manual available
There is a picture of the mainbearing thoug
Traditional design with straight spindel and tapered bearing OD and a tapered ID on the bearinh housing The bearing has a threaded end on both sides With the big nuts you can pull the bearing deeper in de bearing hous making the ID smaller Sometimes you see 3 ridges inside the bearing house So if you pull the bearing in it will get 3 lobs So 3 high spots That seems to give a better lubrication
I would start with checking the spindle It has to be absolutly round
With so much wear I think you need it ground and lapped
Then the new bearing needs to be scraped to a very high standard
Use the same bronze as the original one DO NOT TRY TO IMPROVE THE BRONZE That will change the tribology
If possible check it with a spectrumanaliser That does not tell you everything though As I was told a certain amount of tinoxide gives better properties
But with a spectumanaliser you cannot detect this
Peter

 

[Will Robertson]

Hoi Peter

https://passion-usinages.forumgratuit.org/t1843-mikron-t90

Here you can download a cataloge But not a manual available

Thank you very much - that's very valuable - I downloaded both the catalogues.

It's very interesting for me to know which modules and accessories were available for this lathe because I'm thinking about making my own modules for it - perhaps a stepper motor drive so that it can be used as a very small, very light machining center. The T90 was designed at the cutting edge of technology as one of the first revolutionary modular precision lathes so it seems right to think about designing some new modules for it 80 years later that incorporate some of today's cutting edge technology.

I'm beginning to learn that there's a lot of information available about Mikron lathes and mills in French - https://www.usinages.com/ also has some useful information and photos.

Traditional design with straight spindel and tapered bearing OD and a tapered ID on the bearinh housing The bearing has a threaded end on both sides With the big nuts you can pull the bearing deeper in de bearing hous making the ID smaller Sometimes you see 3 ridges inside the bearing house So if you pull the bearing in it will get 3 lobs So 3 high spots That seems to give a better lubrication

Thank you very much - that's very helpful for me to know the details of how the bearings are constructed and why.

With so much wear I think you need it ground and lapped

I made a mistake in my initial guess - trying it with a micrometer I got a total radial play of 0.25 mm not the 1 mm that I'd initially guesstimated. The lathe does look like it's been used much more roughly than would be appropriate for a lathe of this precision. Is a radial play of 0.25 mm within the bounds of what I could expect to remove by adjusting the bearings?

If possible check it with a spectrumanaliser That does not tell you everything though As I was told a certain amount of tinoxide gives better properties
But with a spectumanaliser you cannot detect this

That tends to depend on the spectrometer - the older XRF spectrometers and the handheld XRF spectrometers for general use are less accurate with light nuclei than with heavy nuclei and typically for oxygen or anything lighter they're fairly hopeless - there are a new generation of more modern, larger and expensive laboratory-based XRF spectrometers available now which can accurately measure the lighter elements - but because of their size, complexity and cost they're limited to laboratories at the moment.

Will

 

[Peter from Holland]

If you can find what lube oil is perscribed the thickness of that oil will be a indication of what endplay the spindle is set by the factory For example A Aba grinding spindle with 0.01mm endplay uses oil as thick as water

 

[Will Robertson]

If you can find what lube oil is perscribed the thickness of that oil will be a indication of what endplay the spindle is set by the factory For example A Aba grinding spindle with 0.01mm endplay uses oil as thick as water

I contacted the manufacturer but all they could say was:

"Sorry to inform you that for this machine type we don’t have any documentation, manual and/or spare parts available as really too old."​

it's only 80 years old.

Unfortunately I don't have clue what the original specification for the play or for the oil was.