Advice please : Quick voltage and amps question + speed control

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Originally Posted by Clive S

How about three steppers:whistle:

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Yeah Clive I have 3 Nema 17 high torque but I wasn't sure if running them constantly for 20 mins would be ok ?

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Originally Posted by Fivetide

Yeah Clive I have 3 Nema 17 high torque but I wasn't sure if running them constantly for 20 mins would be ok ?

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Nema's can run for hours think router and 3d printers, they can also run very hot in access of 60C without problems.

They also have the better torque at lower speeds

Get the 24V PSU and a single PWM controller rated to run all three motors, check the specification of the motors for current draw, you've just referred to the motor ratings as aH (amp hours) which is a battery charge capacity not a motor current draw.
If you don't have one get a multi-meter so you can check voltages and currents once you have something to fiddle with.

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Originally Posted by magicniner

Get the 24V PSU and a single PWM controller rated to run all three motors, check the specification of the motors for current draw, you've just referred to the motor ratings as aH (amp hours) which is a battery charge capacity not a motor current draw.
If you don't have one get a multi-meter so you can check voltages and currents once you have something to fiddle with.

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I might just plump for one of these and a travel adapter and when I have everything working flog it on fleebay again. Super 30V 5A 110V Adjustable Power Supply Precision Variable DC Digital Lab H6TG Or keep it I might want to mess with other stuff later. If it saves me buying the wrong power supply at least that justified the purchase lol

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Originally Posted by Fivetide

Yeah Clive I have 3 Nema 17 high torque but I wasn't sure if running them constantly for 20 mins would be ok ?

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Sure it's OK to run them constantly for hours also, but you need a driver for each and a motion controller also. So it is a bit more complicated. Even if you don't want a driver for each motor, just want to connect all three in parallel it is a fair bit more complicated to do what you are showing in the video.

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Originally Posted by A_Camera

Sure it's OK to run them constantly for hours also, but you need a driver for each and a motion controller also. So it is a bit more complicated. Even if you don't want a driver for each motor, just want to connect all three in parallel it is a fair bit more complicated to do what you are showing in the video.

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Yes But if you had read the other post http://www.mycncuk.com/threads/10360...t-CNC%29/page2 you would have seen that this has be discussed

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Originally Posted by A_Camera

and a motion controller also. So it is a bit more complicated.

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http://hobbycomponents.com/motor-dri...-motor-drivers

But not very complicated as the above linked product has already been suggested, it's as complex a motion controller as is required, as the occasional lost step isn't an issue one pulse generator could be used for all three drivers - Simples! ;-)

- Nick

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Originally Posted by magicniner

http://hobbycomponents.com/motor-dri...-motor-drivers

But not very complicated as the above linked product has already been suggested, it's as complex a motion controller as is required, as the occasional lost step isn't an issue one pulse generator could be used for all three drivers - Simples! ;-)

- Nick

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True, with that simple controller it is much better than three power drill motors. Also more torque even at slow speed.

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Originally Posted by A_Camera

True, with that simple controller it is much better than three power drill motors. Also more torque even at slow speed.

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I have ordered or already have everything for the DC and Stepper builds.
They both have merits :
The stepper build linked to an arduino program will be good for taking the roughed out semi-sphere to an unpolished perfect sphere. I can set the program to speedup gradually and shift the rotational direction. More torque is required because it tends to grab when rough.
But it takes more parts and is a more expensive build. You have to have 3 controllers , flexible adapters and chucks.
The cordless drill version is good for the high speed polishing where torque is not a huge issue, it can also be controlled with an arduino and has a built in gearbox / chuck. Its also a cheaper build, 1 power supply and a single controller. Bit more cooling needed if there is no built in fans.
If .. and I say if ! I get them both working I'll do a vid and some pics.

Yes, the stepper solution is a bit more complicated and more expensive. BTW, rotation direction change with a cordless drill motor is very easy, just switch the polarity on the motor you want to change the direction. Looking forward to see the vid.