Lubrication of plastic on plastic moving parts.

[JohnBayley]

Hi all,

I have a Junghans ATO-MAT W726 wall clock movement and I need advice on lubrication of the balance / drive mechanism. (Note - absolute novice here!)

The power to drive the gear train is derived from a magnetically pulsed balance which carries a small brass helix on its shaft. This helix drives a small plastic pin-wheel which in turn drives everything else.

Can anyone tell me whether this metal-plastic combination should be oiled or left dry? If lubricated, what type of oil is suitable and safe for these two different materials? And if lubricated, I assume low viscosity oil ?

Any information would be much appreciated.

[JohnBayley]

Oops, a bit of a brain-fade here. The topic heading obviously should have been METAL on plastic. Could Admin change the heading?

 

On closer inspection I realize that the helix metal is probably steel; only the shaft carrying it is brass.

[Jon]

There is a Moebius oil called TH7-SC specifically designed for the lubrication of plastics: chrome-extension://oemmndcbldboiebfnladdacbdfmadadm/https://www.moebius-lubricants.ch/sites/default/files/security_sheet/tinf_th7_en.pdf

However, on an ETA chronograph such as the 7750, there is a part called an hour counter lock made of plastic that isn't lubricated, as it is made of nylon, therefore lubrication isn't needed.

Alternatively, you could use silicon grease that won't degrade the plastic. It has to be pure silicon. Alternatively, vaseline will work.