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Duet 0.8.5 with 2 Z-Axis Steppers

Posted by Pole04 
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Pole04
Duet 0.8.5 with 2 Z-Axis Steppers
January 12, 2016 09:14PM
Ok so I got my new shiny Duet 0.8.5 in today and I realized I may have made a mistake...

I am new to 3D printing and I am learning as I go, so please excuse me if I am missing something terribly obvious here.

I have two steppers that drive my Z-Axis, on my old board there were two headers for the Z-Axis, but on the Duet there is only one. Can I use the E1 header to drive the second stepper and just make a configuration change, or is there another way to drive the second stepper without purchasing a Duex? I don't mind the added expense of the Duex, but I don't see that I really have a need for it at the moment.

Thanks,
Pole
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UniTrader
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 12, 2016 10:33PM
dont trust me here entirely, but if i recall the documentaion i read regarding correctly this they are simply connected in parallel - so you could alternatively disassamble the plugs of both and put both cables into the same plug (same color wires to same pin, it should be possible to double them) or create an adapter which doubles the pins available (called Y Cable)

wait for confirmation of others though - i am not absolutely sure on this one (and also new to 3d printing)

Edited 1 time(s). Last edit at 01/12/2016 10:34PM by UniTrader.
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Pole04
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 12, 2016 10:57PM
Hey thanks for the suggestion. Definitely something I am capable of and a quick cheap solution. I will wait for someone else to chime in and confirm before I get to work.

Thanks!
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dc42
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 13, 2016 03:53AM
The best way to drive two Z steppers from a Duet and most other printer electronics is to connect them in series, not parallel. This is how RepRapPro wire them in their Mendel and Huxley kits. Parallel connection is only better if the motors have a rated current of 0.8A or lower and voltage above 4V.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Gaou
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 13, 2016 01:16PM


this is how i connected mine . the photo is from the reprappro documentation .
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dc42
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 13, 2016 05:40PM
Here's another RepRapPro wiring diagram, showing how to connect two Z motors in in series without using extra connectors on the optional linear regulator board for the Duet.




Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Pole04
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 13, 2016 09:05PM
Thanks for the information dc42.

I was able to find a y-connector that was included with my printer kit, but it appears to be wired in parallel and not series (all wires of the same type feed a single terminal). I kit with a ton of terminal and connectors coming in tomorrow. I will have to change these around. I appreciate all you have done for the Duet and RepRap community!
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dc42
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 14, 2016 03:15AM
If you tell us the specification of your motors, I can give more advice on whether you can get away with using that Y adapter.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Pole04
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 15, 2016 03:30PM
I wish I could, but I have been unable to find specs for these cheap Chinese motors. The are from goldenmotors.cn (Part 45HD2037-01 S-22 15/8/27). These steppers came with a kit. I will likely be replacing them in the future, but I need to get the printer up and running again before changing too much.
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dc42
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 15, 2016 07:24PM
Quote
Pole04
I wish I could, but I have been unable to find specs for these cheap Chinese motors. The are from goldenmotors.cn (Part 45HD2037-01 S-22 15/8/27). These steppers came with a kit. I will likely be replacing them in the future, but I need to get the printer up and running again before changing too much.

Are they Nema 17 size motors? If so, measure the resistance of one phase with a multimeter, and the length of the motor body, and we can compare other motors with similar length and resistance to get an estimate of the current rating. The 20 in 2037 may mean 2.0A.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Pole04
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 15, 2016 11:26PM
Pardon my ignorance here. What would be the best way to do this? My old board is not safe to plug in, so I would have to use the Duet.

Also one more question, I am going to need to design and print a mount for the controller to mount it to the printer. Does anyone know what the best mounting material would be in the mean time?
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dc42
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 16, 2016 02:45AM
You don't need a controller to measure the phase resistance, just a multimeter connected to either pair of phase wires on the motor.

As a temporary measure, you can attach the Duet to a piece of MDF using screws and nylon spacers. There are designs for printable Duet enclosures on Thingyverse.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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RickRap
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 18, 2016 02:43AM
I just set up two z-axis steppers on my Duet. I wired them in parallel. These are NEMA 17 from OpenBuilds. I set current to 2.0 in the firmware and they seem to be functioning just fine.
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dc42
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 18, 2016 02:59AM
Quote
RickRap
I just set up two z-axis steppers on my Duet. I wired them in parallel. These are NEMA 17 from OpenBuilds. I set current to 2.0 in the firmware and they seem to be functioning just fine.

I suggest you check how hot that driver is running. Although the stepper drivers are rated at 2A and are well cooled by the PCB, the chip manufacturer only specifies a guaranteed maximum output resistance up to 1.5A.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Pole04
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 18, 2016 05:17PM
Just a quick update, I have made the mount for the PCB and have everything wired on the printer/duet except for the two Z Axis Steppers. I will hopefully have a new multimeter here in the next day or so. I will get back to you with the readings. Thanks for all the help!
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Pole04
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 19, 2016 08:37PM
The motor body is 33mm long. There are larger motors on the Y and X axis, this pair is smaller.
The resistance measures: 2.1 ohms (I am not sure I measured this right, but with two separate sets of pins I got this reading)

I tried mailing golden motors but my mail was rejected by their server, so no luck there. A search of their site does not list these motors. The have the HD series, but they come in a wide variety and this specific model is not listed.
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Gaou
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 28, 2016 01:55PM
Quote
dc42
Here's another RepRapPro wiring diagram, showing how to connect two Z motors in in series without using extra connectors on the optional linear regulator board for the Duet.


david at this diagram the two coils are blue/red and green/black ?
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dc42
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 28, 2016 06:22PM
Quote
Gaou
Quote
dc42
Here's another RepRapPro wiring diagram, showing how to connect two Z motors in in series without using extra connectors on the optional linear regulator board for the Duet.


david at this diagram the two coils are blue/red and green/black ?

Yes, that's correct.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Pumlux
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 29, 2016 05:08PM
One comment from my side,
I suggest to keep both steppers still with their own connector (not wiring both steppers in one print header plug).
On first hand, you can swap steppers easily if one is broken , or you want to remove it from the printer.
On the second hand, I noticed that even if you do not power the controller and you rotate one stepper motor manually, the second will rotate also, as long as wired together.
That is unwanted in the case you need to syncronize z-axis stepper motors.

I made a adaptor PCB to connect both z-axis stepper towards one driver connector. (currently for parallel mode, but serial mode should be doable also)
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Gaou
Re: Duet 0.8.5 with 2 Z-Axis Steppers
January 30, 2016 01:44AM
Quote
Pumlux
I made a adaptor PCB to connect both z-axis stepper towards one driver connector. (currently for parallel mode, but serial mode should be doable also)

that's what i intend to do also . Make a pcb that would be upgradable to 5v regulator to plug the steppers. But for now it would only have sockets for the steppers.
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Pole04
Re: Duet 0.8.5 with 2 Z-Axis Steppers
February 10, 2016 08:52PM
Ok I bought some new stepper motors and wired them according to the diagram above. When i tried to move the Z-Axis, it moved in reverse so I flipped the connector around at the board. They are now moving correctly, but when they are idling they are making a VERY high pitched squeal.

They are 2.0A steppers and I adjusted the amperage accordingly in the config file. I have also tried dialing it back all the way to 1.7A with little to no change in the sqeal/whine. Any other ideas how to get this to stop? It is giving me a massive headache.

Thanks!
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dc42
Re: Duet 0.8.5 with 2 Z-Axis Steppers
February 11, 2016 03:01AM
2A steppers should not be run at 2A because they will get very hot at their full current, and so will the driver chips. 1.7A is about as high as you should go. Try 1.2 to 1.5A.

Why did you buy new stepper motors?

Edited 1 time(s). Last edit at 02/11/2016 03:02AM by dc42.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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RickRap
Re: Duet 0.8.5 with 2 Z-Axis Steppers
March 04, 2016 03:04PM
Time has a way of proving things out.

After running my z-axis in parallel since posting above, one issue has come up.

As I am using bushings rather than crunchy roller bearings, there is more resistance than a typical roller setup. This has caused the motors to clutch or skip or backlash or whatever it's called. So, I am now looking at re-wiring these in series. That will halve the voltage.

My steppers are from OpenBuilds LDO-42STG47-1684A which makes these 1.68 A based on what dc42 mentioned above.
The "rated voltage" is 2.8VDC. Does that indicate that these motors will work fine on 6V?
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