Beetle motors

[teamshock]

Does anyone know a reliable source of the 1000rpm beetle motors? The last few I've ordered have been useless.

Thanks

[Ellis]

Useless in what way? And where from?

[teamshock]

I got them from Ebay a while ago but only just got round to using them. The quality was a bit suspect- opened them up to find that they have the right ratio but the motor has no power whatsoever. It struggled to move Mantle even on 3s.

[Ellis]

You able to find the Ebay seller? Worries me a little as I went for the cheapest option (naturally) for a load of them a month or so back and I can't afford for them to be crap. Will stick a wheel on one and test its torque. Fingers crossed...

[mark_m]

I've tried a few different 25mm motors for my beetle, and made some interesting discoveries. This seems as good a place as any to record it.
I've bought three different types: 1000rpm@12V (~£6.80): http://www.ebay.co.uk/itm/2-x-12V-DC.../330751682081?
500rpm@12V (£6.30): http://www.ebay.co.uk/itm/12V-DC-500.../320926467641?
130rpm@6V (£18.90): http://proto-pic.co.uk/75-1-metal-ge...25dx54l-mm-hp/
_MG_7522.jpg
left to right: 1000rpm ebay motor, 500rpm ebay motor, 130rpm Pololu motor

_MG_7524.jpg
left to right: 1000rpm ebay motor, 500rpm ebay motor, 130rpm Pololu motor
Note the 500rpm and 130rpm motors look very similar, but the output shaft sticks out for the ebay motor. The 1000rpm motor obviously has a plastic end bell. Less obvious and irrelevant to most people (except me, I wanted to use one near an electronic compass), is that it also leaks magnetic field much more significantly than the other two.

_MG_7525.jpg
The front faces and bushes are quite similar, but the Pololu one has a slightly higher quality material/finish to it.

_MG_7526.jpg
Again, they're very similar on the inside. no plastic gears anywhere and all the gears appear to be the same material. The ebay ones use a slightly heavier and darker grease.

I've also connected the motors to a power supply and stalled them at a low voltage:
Ebay '1000rpm' motor: 1.85A@4V
Ebay '500rpm' motor: 0.85A@4V
Pololu '130rpm' motor: 5A@4V

So despite the 500rpm and the Pololu ones looking similar, the Pololu one is likely to be 6x more powerful. I think this is fairly irrelevant if you're using them for a drive application, as my beetle uses four of the 1000rpm motors on 56mm grippy wheels and has pretty good speed and pushing power, but for a lifter weapon it can make quite a difference. My lifter used to use two of the 500rpm motors. When I changed them to the 130rpm motors (overvolted to ~12V, so closer to 250rpm), the peak speed halved but the torque was about ten times higher so it could actually self right and is nearly a flipper now.
I think this just goes to show that you can't take much t=from the scant 'specs' you see on ebay, and even products that look very similar could have very different performance, you just have to try them. I've had a quick look on ebay and I can't see any gearmotors that use the exact same motor as the Pololu ones.

[Ellis]

To add to that, in my experience too, the plastic backed motor cans have vastly more grunt than the metal backed versions. Just two (plastic vers.) drive the heavy (2.5kg) lifter and spinner KE pay-to-drive bots really really nicely. The lifters are especially impressive as the wheels are at the back and they have a scraping wedge.

I bought some 500rpm motors for them thinking the 1000s (ebay) would struggle. After fitting them two things were evident; they had less torque despite having double the mechanical advantage and they were very noticeably timed in one direction. So much so that trims couldn't sort it in conjunction with BB10a ESCs.

I have metal endbell 1000s in Newton and they are also markedly underpowered. Much less nippy drive than the pay-to-drives despite weighing over 1kg less.

[brandon_nichols]

You can try some of Pete Smith's Kitbots 1000 rpm motors. His site is backordered but you can still get them on Robot Marketplace.

http://www.robotmarketplace.com/prod...B-1000RPM.html