Using two motors for the y axis.

Is there a way to use two motors for the y axis on a standard reprap style printer? I am designing a very large printer, 24"+ and it needs two y axis motors.

Where on the ramps should I split, can the signal be split? Do I need a special signal splitter circuit coming off the ramps or can I just literally use a Y-cable and go to the motors? I am assuming not, since these motors are brushless and that might totally screw up the timing of the motor (I read somewhere that brushless motors dont like when you run parallel signals from the source, or something like that).

Thanks

The Z motors are typically run in parallel. Is there something different about what you plan to do on the Y motors? If not... My guess is it works.

Nothing different, do I just get a stepper motor Y cable? Is that something readily available or do I have to make my own?

Thank you

I haven't do it myself, but it should be pretty easy. This is assuming you are only using 1 extruder.
Just plug in a polulu board into your E1 location and drive the 2nd Y axis stepper at that location.
Open Arduino, open tab Configuration_adv.h
Uncomment this line: //#define Y_DUAL_STEPPER_DRIVERS

Would just a stepper motor Y cable work if it comes off the ramps? from the 4 pins Y axis output?

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Originally Posted by DBFIU

Would just a stepper motor Y cable work if it comes off the ramps? from the 4 pins Y axis output?

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That depends on your motors and the currents / voltages of your drivers. It is never a good idea to use steppers like that as they have no feedback so if one motor misses a step they will forever be wrong until you intervene and align them again. The same is true for double drivers though.

The only way to align them is to have one end where you know they will both stall in the same position and drive against it with more pulses than are needed. Once that is done then when reversed they will be aligned correctly.

Not worth the hastle really, get a bigger stepper and a long rod.

Quote:

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Originally Posted by Mjolinor

That depends on your motors and the currents / voltages of your drivers. It is never a good idea to use steppers like that as they have no feedback so if one motor misses a step they will forever be wrong until you intervene and align them again. The same is true for double drivers though.

The only way to align them is to have one end where you know they will both stall in the same position and drive against it with more pulses than are needed. Once that is done then when reversed they will be aligned correctly.

Not worth the hastle really, get a bigger stepper and a long rod.

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I am ok with that, what stepper would you suggest? NEMA 23? I am only familiar with NEMA 17. Would the DRV8825 stepper driver be able to handle the current of a NEMA 23? How about the ramps?

I dont intend to go crazy, just one size up motor would be nice. I would really like to use a NEMA 23, ramps, standard DVR drivers and call it a day. Is this unreasonable?

My CNC mill uses Nema 23 with Ramps and Marlin. Bit slow but it is usable. I can't get more than 1 amp because of the resistor used on the stepper driver boards but CBA changing it.

Ok, so is the limiting factor the ramps? I want to be able to take advantage of the bigger motor, but if it cant get the current then there's no point.

When you say slow, do you mean it has a limited top speed, what about accelerations? Can I at least hit 1500mm/s2 or about the equivalent of 250 mm/s out of it? (using standard 3D printer pulleys etc...)

What is CBA?

CBA >> can't be bothered (nearly)


Limited top speed and acceleration. I am not about to do the arithmetic but 1 amp isn't enough for my NEMA 23 motors, I would like 3 but 1 is the maximum that the stepper drivers will allow due to the sense resistor that was fitted when they were made.

When I can be bothered I will change the stepper driver from 4988 to 8825 and set the sense resistor to allow the limit for the board (2.5 amps I think).

Thanks for the input. I use the 8825 drivers on all my ramps boards. Do I just turn the pot on those until I hit 2.5 amps? How do you measure the current your motors are pulling?