Replacement gears for Chester Champion 20V mill

[CharlieRam]

So it appears I have overworked my Champion 20v mill, the main plastic drive gear has lost all but about 5 teeth! I was using a fly cutter set at 60mm with 0.5mm depth cut and approx 200mm/min feed (just over one rev of handwheel per second ish!), Is that too much for a hobby mill? I was milling a 60mm wide channel in one of my alu plates and got to about 8mm deep. TBH it did sound a bit rougher than when I used my mill the last time to do another channel which went fine so maybe the gear was on it's way before it mangled. Cutter was just reground and was nice and sharp.
Anyway I have ordered a new top gear which took longer to order than it should but I have since noticed that one of the inner gears (low) is also missing a few teeth and I'm wondering if it is possible or advisable to get metal replacement gears and if so, where from? I also wasn't too pleased that I had to pay for the replacement gear as I only had the machine for 7 months, I understand that it could be down to abuse but I would of thought .5mm depth in alu on 60mm diameter would be easily achievable?
18198
Cheers, Charlie

[m_c]

It's a well known issue with X2/SX2 style mills. Have a search over on the benchtop forum on cnczone - http://www.cnczone.com/forums/benchtop-machines/

Try a search over there for stripped gear, or belt conversion, as a conversion to a toothed belt was often mentioned.

[John S]

SX2 is a different animal. it has the brushless motor on it and timing belt drive, no gears.

[CharlieRam]

I've seen the belt mod somewhere but can't help thinking rather than having plastic gears why not have metal ones and use a shear pin to drive it, it would be much cheaper to replace a shear pin.

[lucan07]

I have one model down the X1SP 500w brushless with timing belt which converted to CNC and tend to use 0.25mm DOC with flycutter at 900mm/m without problem, these are mini in my case micro machines though and need to be listened to especially with geared drives if they sound unhappy or under stress they are prone to self destruct if not listened to. #As for getting new gear for it I can only think of http://www.beltingonline.com/gears-racks-366/?zenid=31e95ur01grm1611ed7i9j90o4 they are best value I have found.

[komatias]

Gears have backlash and this shows up as ugly surface finish. I seem to remember that littlemachineshop in the US did metal gears. If you have time and cash I would say go 700W brushless motor with belts.

[magicniner]

HPC Gears supply a huge range of gears

http://www.hpcgears.com/

- Nick

[CharlieRam]

Feeling a bit thick here, How do I know what gears to order if I went that route (count the teeth,O/D and angle or would I get a matched pair with the same centre distance?), TBH I would rather the belt conversion but for now a replacement gear was the quickest option but £18 for a bit of plastic which I know is going to fail fairly quick is a bit gutting. After owning the M/C for only 7 months I would of thought it's not fit for purpose if the gear mangles like that? I mean with a bed size of 700mm I'm not going to be machining watch parts am I!