dc motor - spindle / shaft drive

[dsc]

That was the main problem with DC brushless motors, at least the ones I've found on the net. It's either too low with the torques or too high with the speeds. As I said steppers seems to be ok due to the fact that their torques are reasonable at lower speeds and sizewise they are small, quiet and fit in perfectly in the box I've designed. Even adding a driver and power supply, it seems to be less than £200 which is reasonable for the budget I have. As I said before, I need to squeeze this in a rather tight space, 110mm x 150mm x 2800mm, so this eliminates big, beefy motors. I'd also rather go for an off the shelf kit as I've got enough problems with cuttings parts for the enclosure.

Thank you kindly gents for your suggestions and discussion.

Regards,
dsc.

[JAZZCNC]

Just use a stepper with integrated driver like this SYINTSD233-4 (INTERGRATED STEPPER MOTOR)

Very neat and compact and if you Gear it 5:1 then it should do the job. (Or find larger Nm version and keep 3:1)

Have you thought about the heat a stepper produces.? For short grinds then imagine shouldn't be a problem but still need to consider the heat and possible fans if enclosed and used for lengthy periods.?

[Jonathan]

Just use a stepper with integrated driver like this SYINTSD233-4 (INTERGRATED STEPPER MOTOR)

Very neat and compact and if you Gear it 5:1 then it should do the job. (Or find larger Nm version and keep 3:1)

300rpm is needed, so at 5:1 the motor is spinning at 1500rpm. At that speed the output torque is about 0.46Nm, which with the 5:1 ratio means 0.46*5=2.3Nm. The torque at very low speeds, i.e. when starting is 1.24Nm, so 6.2Nm at the grinder shaft which is below the 9Nm you specified.

Just use this spreadsheet to compare the different motors at Zapp and you'll be able to determine which motor/driver, if any, is suitable. It's substantially cheaper to use a separate motor and driver. The PM752 from Zapp is quite compact and I'm sure there are others.

[JAZZCNC]

300rpm is needed, so at 5:1 the motor is spinning at 1500rpm. At that speed the output torque is about 0.46Nm, which with the 5:1 ratio means 0.46*5=2.3Nm. The torque at very low speeds, i.e. when starting is 1.24Nm, so 6.2Nm at the grinder shaft which is below the 9Nm you specified.

Yep correct Boy wonder.!! Didn't really give it much thought and concentrated on the Nm and need for compact design but missed the 300rpm required.!!
Agree that with 300rpm needed that 3:1 and larger motor would be better suited. To keep the compact electrics then the UIM24004 miniture drives go upto 4A so will be ok for a 3Nm motor.!

That said would have thought 6Nm when attached to dedicated grinder should easily crush a Coffe bean.? . . . But hey I drink tea so what would I know.!!