Is it possible to put 3 motors on one driver?
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We obviously have two headers on the Z driver allowing dual Z motors (i3 style) to be connected. Is is possible to connect 3 Z motors to the one driver? If so how would you go about doing that?
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Yes, but...
It divides the current three ways, and that is very very likely to be "beyond the point of diminishing returns".
What is your actual goal?
Delta / Kossel printer fanatic
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The Z driver has two headers in series with each other; I guess there is no practical reason why you couldn't extend that to three motors in series - but you'd probably be limtied by the speed of which you could drive them due to the voltage being split and the back emf increasing.
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@bearer This is for a Z axis so speed is not really my priority here. I guess it would work acceptably.
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@Danal My actual goal? Its to drive 3 motors for Z without having to buy an expansion board.
Since this is a Z axis I dont need much speed or current on the motors so I suspect it would be ok.
My z is lifted by 3 Z motors with the idea being that I can convert that to 3 independant drives later on for ABL but currently I cant afford the extra board / want to prove out the Z axis first before I go and buy another dueX.
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Current won't be an issue unless you wire the motors in parallell, but then they could get varying drive currents unless very closely matched. If speed isn't a concern i'd try pushing Vin to the max and go for a serial configuration.
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I would strongly consider one motor and a belt to the three screws.
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@Danal Do you have a reason for that? Thats what I am actually currently using but alignment / calibration of that is a nightmare
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Three motors on one driver will have EXACTLY the same nightmares... with the additional possibilities of over/under current, o/u volt, skipped steps, etc, etc.
It CAN be done, no question. It gains nothing that I can see over a belt .
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@EdChamberlain said in Is it possible to put 3 motors on one driver?:
but alignment / calibration of that is a nightmare
At least it's a one time nightmare. Once it's in place it should be pretty stable. With independent motors you've got to get them in sync constantly after the fact and with only a single drive that's not exactly trivial either.
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@Phaedrux said in Is it possible to put 3 motors on one driver?:
With independent motors you've got to get them in sync constantly after the fact and with only a single drive that's not exactly trivial either.
Not trivial, but here is how you could do it. Use the mechanism here
https://duet3d.dozuki.com/Wiki/Using_the_manual_bed_levelling_assistant but set the screw pitch parameter to be the amount of Z movement per 4 full steps. Run it, then reduce the Z motor current, round the suggested corrections to the nearest integer and turn the leadscrews by hand that number of motor clicks.RRF 3.01 may keep the motors better in sync through power cycles than older firmware.
Duet WiFi hardware designer and firmware engineer
Please do not ask me for Duet support via PM or email, use the forum
http://www.escher3d.com, https://miscsolutions.wordpress.com -
@dc42 said in Is it possible to put 3 motors on one driver?:
@Phaedrux said in Is it possible to put 3 motors on one driver?:
With independent motors you've got to get them in sync constantly after the fact and with only a single drive that's not exactly trivial either.
Not trivial, but here is how you could do it. Use the mechanism here
https://duet3d.dozuki.com/Wiki/Using_the_manual_bed_levelling_assistant but set the screw pitch parameter to be the amount of Z movement per 4 full steps. Run it, then reduce the Z motor current, round the suggested corrections to the nearest integer and turn the leadscrews by hand that number of motor clicks.RRF 3.01 may keep the motors better in sync through power cycles than older firmware.
Of course! That's clever.
