I have a machine that has two motors for the x axis could anyone explain how I setup Mach3 to run this machine please, am I right in thinking slave one of the 2 motors?
Yes that's right. Set one of the motor pins as X, and the other as one you wont use, say C. Then in Mach3 go to 'Config', 'Slave Axis' and click the option to slave C to X, and leave the other axes on 'none'. Then restart mach and it should just work.
That's one way - you can also connect 2 stepper drives to the same mach3 output or if the drive is powerful enough even 2 motors to the same drive.
I did both for many years and still do so without any problem. Why should there be any issue with reliability or accuracy (as long as the drive is not overloaded)?
Its a convenient way to save cost (2 motors @ 1 drive) and / or output pins.
There is only one - theoretical - drawback: you can't reference both axis independently. "Theoretical" because if you have a double X axis configuration you need to be sure they stay in sync - if not you're in trouble anyway no matter how the motors are connected.
I used the method of splitting the signal from one port to two drive in mach until i swapped over to USBCNC and even then did the same there, works like a charm no issues as far as I'm concerned. But the 2 motors one drive is not a good idea.
If your working at low feed rates then it can work and indeed the RepRap boys often use this method but they are only using low feed rates with no stress on PP. But any decent CNC machine that wants reasonable feed rates and uses MS to help with smoothing motors will potentially fall foul of using this method.!!
While this can and does happen with Each drive having it's own signal it's far far less likely to happen even at high micro stepping if the PP is only even half decent as it's not sharing and virtually Nil chance with good PP.
The other problem with this and twin motors on one axis is you can't control one motor individually for homing and squaring the Gantry etc so has the dropped steps start accumulating eventually racking the gantry there's nothing you can do about it other than Manually loosen the couplers and reset square.
With 2x motors sharing one drive there's problems from features like Mid band resonance or other correction features. The drive doesn't know which motor to apply the compensation too so only one drive gets it this then throws the other into resonance and it can stall. Which drive gets current reduction etc all bad news and not worth the trouble IMO.
So all in all it's a shite idea and not required really has most BOB's are 5 axis and the software allows for slaving motors. The PP provides enough output signals so why take the risk of accumulative errors creeping in to what should be an accurate system.!!
Think about this.?? . . . .If 2 drives where ok to be run from one signal don't you think the likes of Lead shine and other drive manufactures would have produced a two drives in one package for those that needed them.!!
- You can connect them in parallel: current needs to be doubled and motor performance will stay the same (I use it this way on one machine).
- You can even connect them in series: Quite interesting as current stays the same - so you can e.g. connect two 5A montors to one 5A drive and holding torque and performance at low speeds will still be the same. Only drawback: torque at higher speeds will drop fast and you won't achieve full speed.
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