Two stepper motors in parallel

dc42 · 13 Dec 2020, 07:47

A filament monitor does not control a motor, it monitors filament motion and compares it with the commanded motor movement. If you configure a tool to use two extruders, each one can have its own filament monitor if you wish, or you can use a filament monitor on just one of them.

Dep · 13 Dec 2020, 08:07

@dc42 Thank you very much for your reply!

zapta · 13 Dec 2020, 17:53

@Phaedrux said in Two stepper motors in parallel:

Having an bearing axis at the center of mass should make it relatively easy to feed though. Doesn't take much to make a wheel roll, regardless of weight.

That's the approach I took for my 1Kg spools after considering motorized options and it works very well. It rotates so easily that the filament 'springiness' keeps one or two loops in the air and the spool even rotates backwards when the printing head moves toward it.

It's important to have the bearings at the center. Other configurations where the spool 'sits' on bearing don't rotate as easily for some reasons which I didn't expect.

For motorized solution you probably want to have a tension sensor of some kind because it's difficult to get perfect sync between the two motors and relying on slip will actually increase the required pulling force by the main extruder.

My 2c. I am not a mechanical engineer.

Dep · 17 Dec 2020, 19:54

@zapta this configuration does not suit for me, since tube length over 2,5 meters. And there is a need to pull the filament completely out of it.

Dep · 17 Dec 2020, 20:00

There is one more question: after assigning two motors to 1 extruder, I found that only one motor is rotating. The second works only if i send the command:

M567 P0 E1:1; mixing

It seems to me somehow wrong. I see that the M563 command has the L parameter:

 Lnnn Drive to use for filament mapping parameter. By default RRF will use the first and only extruder drive if this parameter is not specified (supported by RRF> = 2.02)

Perhaps this is what I need, but I cannot find information on how to use it.

Can you clarify this question?

Dep · 19 Dec 2020, 12:26

@dc42 can you tell me about the last question? I cannot find information on this parameter.

Dep · 23 Dec 2020, 21:31

In the description of the command "M563: Define or remove a tool" I see the parameter:

Lnnn Drive to use for filament mapping. By default RRF will use the first and only extruder drive if this parameter is not specified (supported by RRF> = 2.02)

I thought this is just for the case when two motors are installed on 1 extruder. I have not found information on this parameter anywhere.

Dep · 23 Dec 2020, 21:45

@dc42 Yes, but the question was:

can i connect a magnetic filament monitor to one Toolboard 1LC board but control the motor on another board?

And now I tried to connect the monitor to another board. I receive the following message:

M591 P3 C "31.io1.in" D0 S0
Error: M591: Filament monitor port must be on same board as extruder driver

I need to control the motor "31" since motor "21" it is used only for loading and unloading the filament, the current on it is minimal and it skips a little steps because it is impossible to precisely syncronize. But the monitor is connected to the "21" board (because the other board is far away, it is inconvenient to pull the wires there).

Still, is it possible to connect a monitor to one board and control the motor on another board?

dc42 · 24 Dec 2020, 08:05

@Dep said in Two stepper motors in parallel:

Still, is it possible to connect a monitor to one board and control the motor on another board?

No, that isn't supported. The reason is that when data is received from the filament monitor, the firmware needs to fetch the step position of the extruder motor immediately, in order to compare commanded vs. measured movement.

Dep · 24 Dec 2020, 17:58

@dc42 Ok thanks David!

maddy · 28 Jan 2021, 03:52

@dc42 I want to use 2 Nema 23 high torque motors for the y-axis with Duet 3MB 6HC and 32v power supply. Will the series connection of such motors work with the default drivers of Duet 3? If not, how can I fix 2 motors for y-axis? Do I need any additional board for another motor of y-axis?

dc42 · 28 Jan 2021, 09:58

@maddy said in Two stepper motors in parallel:

@dc42 I want to use 2 Nema 23 high torque motors for the y-axis with Duet 3MB 6HC and 32v power supply. Will the series connection of such motors work with the default drivers of Duet 3? If not, how can I fix 2 motors for y-axis? Do I need any additional board for another motor of y-axis?

If you connect them in series, then at high speeds that will limit the available torque and increase noise. Better to connect them to separate driver outputs.

maddy · 28 Jan 2021, 14:07

@dc42 said in Two stepper motors in parallel:

nect them to separate driver outputs.

If I understood properly, I don't need any expansion board for additional drivers. is that right?. My Duet 3 6HC can support 2 motors for y-axis, 1 motor for each x-axis and z-axis, and 1 for the extruder motor. e.g. M584 X0 Y1:2 Z3 E4.
Please correct me if that is not right. thank you for your prompt response.

jay_s_uk · 28 Jan 2021, 14:18

@maddy said in Two stepper motors in parallel:

@dc42 said in Two stepper motors in parallel:

nect them to separate driver outputs.

If I understood properly, I don't need any expansion board for additional drivers. is that right?. My Duet 3 6HC can support 2 motors for y-axis, 1 motor for each x-axis and z-axis, and 1 for the extruder motor. e.g. M584 X0 Y1:2 Z3 E4.
Please correct me if that is not right. thank you for your prompt response.

That's correct

maddy · 28 Jan 2021, 14:36

@jay_s_uk thank you