Microrotor brass bearing replacement

Diabolik · Dec 26, 2020

Following a couple of attempts, I have designed a fix for the newer microtor bearings that are so prone to failure. The new bearing is made of brass and is tapered so glides over the tapered base of the microrotor pinion. Everything fits snugly with hardly any play and when tested, rotated with very very well ...

Thoughts ?

CafeRacer · Dec 29, 2020

If it works and its cheaper than sourcing a new UG bearing, then it sounds fantastic to me! 😀

WhereMadnessLies · Jan 2, 2021

This could be quite useful to a lot of us Polerouter enthusiasts. Would each new brass bearing have to be made specifically for an individual movement (as the wear levels will be different on every movement) or would just a "standard" part work?

I have a cal 1-69 that I believe would benefit from this sort of fix so I'm quite excited to see how this develops.

Diabolik · Jan 6, 2021

You are right. There are a multitude of possible failures and maybe there's a more elegant way to sort this one out. The 5 roler bearings can be replaced, it is just a mater of finding the micro ball bearings or something that is similar in size. The roler bearing surfaces (bearing surface A and B) need to be refaced as they are usually damaged (not hardened steel) and rotor re-assembled ..

Ted1858 · Jan 6, 2021

Just for my knowledge - is there a particular microtor movement that this type of issue is seen in (cal 69)? Or is it all of the microtor movements?

CafeRacer · Jan 7, 2021

Ted1858
Just for my knowledge - is there a particular microtor movement that this type of issue is seen in (cal 69)? Or is it all of the microtor movements?

Mostly caliber 68/69/1-69 has this specific issue with the bearing, the earlier 215/218 based rotors used a different system (but ultimately suffered from the same problem of wear).

Weihao · Jan 7, 2021

My Polerouter with 215/218 movement has a soft metal friction sound when I shake the watch. Does that mean that it is now suffering from this issue? I did ask a watchmaker about it and he said it was perfectly normal.

CafeRacer · Jan 8, 2021

W Weihao
My Polerouter with 215/218 movement has a soft metal friction sound when I shake the watch. Does that mean that it is now suffering from this issue? I did ask a watchmaker about it and he said it was perfectly normal.

Impossible to diagnose confidently without having the watch in the hand unfortunately.

Weihao · Jan 8, 2021

CafeRacer
Impossible to diagnose confidently without having the watch in the hand unfortunately.

Thanks. Looks like time for a service...

Diabolik · Jan 10, 2021

Well, refacing and using a brass bearing works. Not sure how long it would last. That is the next thing to test. The microrotor pinion become quite rough over time (see image) so need to be re-faced (faces marked in red) ...

Bearing in blue ...

Microrotor Pinion

Brass bearing

Just a matter of re-assembling the movement and it'll be ready for testing ...

PS: I am looking for some old worn out bearings to try out if anyone has anything, PM me.

PiePanPark · May 19, 2022

Diabolik. THank you for the post. I have the same issue on a cal 69 with slop in the oscilating weight bearing. There are no 0.5mm thick bearings to purchase commercially. WIll need to use your brass bushing repair. Where did you source the bushing? Is it just friction fitted? some insights will help me immensely.

TIA

Dan S · May 19, 2022

PiePanPark
Diabolik. THank you for the post. I have the same issue on a cal 69 with slop in the oscilating weight bearing. There are no 0.5mm thick bearings to purchase commercially. WIll need to use your brass bushing repair. Where did you source the bushing? Is it just friction fitted? some insights will help me immensely.

TIA

PiePanPark · May 19, 2022

Dan S

That's a nice watchmakers lathe, but it doesnt answer my question.

Dan S · May 19, 2022

PiePanPark
That's a nice watchmakers lathe, but it doesnt answer my question.

i suspect that it does.

PiePanPark · May 19, 2022

Dan S
i suspect that it does.

if so, what is the inner and outer diameter of the bushing? How thick is it? Where was it sourced? :^/