This is a good question. I would not mind hearing everyone's input on this issue.
Stepper motors in parallel?
Just wondering if it is major no-no to wire two steppers in parallel?
Say i had two identical steppers on the x axis moving the gantry, one on each matching ball-screws. Am i just inviting a whole world of nightmares or sharing the required torque needed to move the gantry? This will also remove the need for a belt whipping around. I figure the chances of all units (Steppers, ball screws) being identical are far from perfect but the difference would be low rather than high.
Any help would be great,
Boothie
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This is a good question. I would not mind hearing everyone's input on this issue.
1. Running two steppers off one drive is risky. Really messes up microstepping and any anti-resonance circuitry. Since motors are generators too it you get the possibility they fight each other.
2. There is a 5% tolerance in position from motor to motor. There is a possibility of a 10% spread beteen two motors (just like there is a posibility they could be right on). Once again one ends up dragging the other along.
Running two motors on one drive, as attractive as it is financially, is a bad idea technically.
Running two motors on two drives on the same shaft is just a waste of money. They will still end up fighting each other for position. It's almost always cheaper to use a larger motor than two smaller ones.
tomCAUDLE
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It works OK so long as you don't need the motors to turn faster than 4 revs/sec (240RPM). Step motors don't play nicely together above that speed. One will drive the other into resonance and stall above that speed.
Mariss
parallel steppers of different make and model
Hi,
I'm a bit late to the party, but what if the stepper motors are of a different make, model, and size?
This may sound like the last thing you'd ever want to do, but I have good reasoning:
I would like to utilize two different sized motors in a push-pull filament drive system in a 3D printer. The rear stepper (push) would likely be a nema 17, while the pull motor would be something smaller, in an effort to limit the amount of weight at the print head.
The steppers would be moving very slowly - no more than about 5-10 rpm... what are the issues with this setup? is it even possible?
THANKS!
If matched motors don't work well (and they don't) then unmatched motors would make it even worse. It's not even a good idea to have two steppers with different drivers connected mechanically (to the same shaft) for the same basic reasons. Motors are generators when turned by an external force. Two two motors on the same drive shaft will tend to fight each other rather than move in harmony.
TOMcaudle
www.Candcnc.com
I will offer my opinion for whatever you think it is worth.
Motors that small use little power, so you can drive them with transistor arrays like ULN2004 which I just bought for 23 cents each. They will drive 1/2 amp at better than 25 volts. They only require TTL drive to do this. That can be obtained from your primary stepper controllers output. How well it would work is anybody's guess. ULN5804 stepper translator drivers are available at Alltronics for about 10.00 US each and might be a better solution, driven from the Logic side of the primary stepper's controller. I would allow some slack between the steppers (in the filament) with perhaps something, (a pulley?) to prevent it from going "HayWire". An easier solution would be to mount the spool above the printer and use gravity assist.
As for the uln2004 s I bought, I am going to try them with a PIC and Roman's LiniStepper in place of the TIP transistors, just to see if i can release the Magic Smoke
For the total cost of about 5 bucks it is something I am going to try.
We're not in business to make parts, we're in business to make money, making parts is just how we do that.
Done all the time for the Z axis on the Prusa Mendel 3D printers:Originally Posted by boothie
http://www.reprap.org/wiki/Main_Page
Using 1 motor driver wouldn't be a good idea,
though a common enough method for running 2 motors so that they step in unison,
but in reverse direction of each other, for machines with wide gantries in need of
2 motors to drive them, is to intercept and daisy chain the main step signals
normally sent to the 1 motor driver board.
These would be the 2 main wires controlling the input, single step and direction.
If the driver board has power saving features, any additional control wires could also
be intercepted.
There are various methods to implement this.
Often there is enough output port logic signal strength, that if the inputs to the
driver boards are diode logic gates, no signal ambiguity would occur.
You can can easily invert the direction signal for an opposing motor,
with a discrete logic gate placed before the second driver board's input.
If needed, a weak logic signal can be stepped up using a small inverter circuit.
Breakout boards can have additional outputs for these occurances.
Mach also gives an option for slaved and inverted stepper motors on the same axis.
Hope this helps.
Possible, IF
It's possible, IF done correctly, and with motors of limited power.
Use identical motors and balls screws.
Use a current drive into each motor, NOT a voltage drive. This means having series resistors between the windings and the driver - separate sets of resistors for each motor!!!
You will need to use a higher voltage than what the motor is rated for, and to work out the correct resistors for this to get the rated current.
This is not easy unless you have a few electronics tools, but it can be done.
This does NOT mean putting two steppers on ONE shaft!
Cheers
