Hi Guys n Gals,
Going for a belt conversion was the first thing I considered to replace the nasty plastic gears. My mill design makes it almost impossible to do a belt conversion job without major construction work.
In my case it was only after the top gear failed and was removed that I discovered that the plastic duplex gear inside the head casing was machined off centre. When rotating the spindle by hand I could feel that it was very tight in one spot and this was causing the repetitive thumping as the spindle was turning. It was this that prompted the investigation into replacing this gear with metal ones.
Having made that decision it was a no brainer to go ahead and replace all of the plastic ones and in my case the bronze gear on the motor shaft as well. As noted in my other thread, I used a 4mm square plastic key in the top gear as a shear pin.
The difference in the mill performance is astounding ! It is not really any noisier than it was before, it runs more smoothly, the surface finish is better and the spindle takes much longer to come to a stop. A more noticeable difference is that the motor gets nowhere near as hot as it did before.
After the original motor went up in smoke I fitted a fan to keep the replacement cool. Now the fan is no longer in use, though I am going to fit a thermistor at some point so that the fan will only start up if the motor gets too hot.
