Best type of ancilliary motor

dc42

Unless whatever it is you want to move is very lightweight, I suggest a DC motor.

deckingman

@dc42 said in Best type of ancilliary motor:

Unless whatever it is you want to move is very lightweight, I suggest a DC motor.

Excellent. Brushless I assume?

Dougal1957

Ian how about a brushless RC Motor driven with an ESC Which in turn is controlled by a servo output (The esc takes in the DC Supply and then drives the motor.

Would think you would need a low KV one mind (KV being the RPM per Volt supplied rating)

Motors

ESC's

ESC Are rated useing a S figure which means the number of Lipo Cells it is designed to operate with.

HTH And that I am not trying to teach you to suck egg's

Doug

ps there are Brushed versions of those as well

deckingman

@dougal1957 said in Best type of ancilliary motor:

Ian how about a brushless RC Motor driven with an ESC Which in turn is controlled by a servo output (The esc takes in the DC Supply and then drives the motor.

Would think you would need a low KV one mind (KV being the RPM per Volt supplied rating)

Motors

ESC's

ESC Are rated useing a S figure which means the number of Lipo Cells it is designed to operate with.

HTH And that I am not trying to teach you to suck egg's

Doug

ps there are Brushed versions of those as well

Thanks Doug - you're not teaching me to suck eggs. I know next to nothing about motors, hence my asking for advice here. I'd never heard of an ESC (but I'm guessing it stands for Electronic Speed Control?)

For the particular application I have in mind, the motor (or at least the output shaft) would need to rotate slowly. Possibly down to 60 rpm, maybe even less or it could be up to 300 rpm but I doubt much faster. From what I can tell, those RC motors and ESCs would be designed for much higher speeds yes?

Dougal1957

Yep normally but some are quite slow it is a matter of selection

RCarlyle

For low force at 60-300 RPM, I'd probably just find the cheapest NEMA 17 I can find off Amazon. Just about any NEMA 17 will work fine up to 300 RPM, and you know the Duet can run a stepper. Or, wait, do you need perpetual rotation? Does RRF have an RPM-based stepper motion command?

If you don't want use a regular stepper, I'd go with a cheap surplus DC gearmotor.

deckingman

@rcarlyle said in Best type of ancilliary motor:

For low force at 60-300 RPM, I'd probably just find the cheapest NEMA 17 I can find off Amazon. Just about any NEMA 17 will work fine up to 300 RPM, and you know the Duet can run a stepper. Or, wait, do you need perpetual rotation? Does RRF have an RPM-based stepper motion command?

If you don't want use a regular stepper, I'd go with a cheap surplus DC gearmotor.

Thanks. I wondered about a small stepper (as per my OP when I mentioned a Nema 8). Yes I do want continuous rotation while printing (perpetual is a bit much to ask for ). I already use the 10 drivers that are on the Duet and Duex5 and I have plans for two more added to the ConnLCD connector so that's my maximum quota of stepper drives taken care of.

The main reason for starting this thread was to find out what would be the best choice from a Duet point of view, given that I might want to vary the speed. It seems like a geared DC motor is the consensus.

Thanks for the input.

RCarlyle

@deckingman If you want approximate RPM rather than position, then yeah, I'd do DC motor (with diode) on a heater output. RPM will drop a bit with increase in load but if you have a gearbox it shouldn't drop much. Redefine the heater output as a fan and control with fan PWM settings and you're in business, I think.

deckingman

@rcarlyle Thanks. Out of curiosity, if load increased to the point where the motor stalled, I'm assuming that would be a bad thing and likely burn out the motor. Is that a correct assumption?

RCarlyle

@deckingman typically yes, cheap DC motors will overheat and burn out if held stalled for more than a few moments. Less of an issue if you’re giving it lower voltage to regulate down speed already (eg 20% PWM). You can also get gearboxes with clutch / slip type mechanisms but I wouldn’t know offhand where to order such a thing off the shelf.

Could probably design yourself a printed clutch with some washers and a spring or something.

deckingman

@rcarlyle Thanks. Thought so. I can make a clutch, that's no problem.

Dougal1957

@deckingman

Ian

this may be of interest motors etc depends a lot on how much power and what sort of RPM You need?

Doug