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ghce
·Just had my Kogan dual watch ( single head) apart for repair as the head had gone all floppy ( dont start!)
It was still working but obviously something was seriously amiss mechanically.
I followed this guys disassembly even though his was a dual head dual watch winder , mine being a dual single head the technique was the same.
Kogan Winder
https://www.dicksmith.co.nz/dn/buy/dual-automatic-watch-winder-and-storage-box/
Opening the gearbox assembly revealed no bearings only steel on steel or some other alloy, might have been a low grade bronze bushing to shaft which had seized onto the shafts then rotated as one to wear out the plastic locating mount on the box.
My conclusion was other than the poor design for the rotating bearings was that they had appeared to lubricate the bush to shaft with the same plastic grease as the plastic gears were lubricated with, a big no no for metal to metal surfaces as the results had shown with close to 0.25 to 0.5 of a millimetre of the shafts bearing surface circumference being stripped away from both ends of the output drive shaft, how a low power 3 Volt motor rated at 50 mA could do that boggles my mind! especially when this watch box only is 2 and a half years old and has only seen intermittent service.
All I could do was clean it up and re-grease the bushings with real bearing grease ( seems little point with that huge wear) and pack out the plastic bushing housing to limit the amount of play of the shaft / bushing assembly which has considerably reduced the head flopping around and makes its serviceable for the mean time but I will need to find a new motor assembly and box off of Ali-express, they all look pretty compatible and cheap to replace this Chinese branded and made (not a Japanese Mabuchi unit ).
The design execution of this Chinese motor assembly leaves a lot to be desired and I would suggest that preventative action be taken if you purchase one of these units by opening the box up and do a quality control of the shaft and bushing lubrication.
It was still working but obviously something was seriously amiss mechanically.
I followed this guys disassembly even though his was a dual head dual watch winder , mine being a dual single head the technique was the same.
Kogan Winder
https://www.dicksmith.co.nz/dn/buy/dual-automatic-watch-winder-and-storage-box/
Opening the gearbox assembly revealed no bearings only steel on steel or some other alloy, might have been a low grade bronze bushing to shaft which had seized onto the shafts then rotated as one to wear out the plastic locating mount on the box.
My conclusion was other than the poor design for the rotating bearings was that they had appeared to lubricate the bush to shaft with the same plastic grease as the plastic gears were lubricated with, a big no no for metal to metal surfaces as the results had shown with close to 0.25 to 0.5 of a millimetre of the shafts bearing surface circumference being stripped away from both ends of the output drive shaft, how a low power 3 Volt motor rated at 50 mA could do that boggles my mind! especially when this watch box only is 2 and a half years old and has only seen intermittent service.
All I could do was clean it up and re-grease the bushings with real bearing grease ( seems little point with that huge wear) and pack out the plastic bushing housing to limit the amount of play of the shaft / bushing assembly which has considerably reduced the head flopping around and makes its serviceable for the mean time but I will need to find a new motor assembly and box off of Ali-express, they all look pretty compatible and cheap to replace this Chinese branded and made (not a Japanese Mabuchi unit ).
The design execution of this Chinese motor assembly leaves a lot to be desired and I would suggest that preventative action be taken if you purchase one of these units by opening the box up and do a quality control of the shaft and bushing lubrication.
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