Adding 2nd motor to ULS 6.60

[Trey Tull]

I have a ULS VLS6.60 and I'm wondering if the wiring harness that powers the rotary, could power two steppers at the same time. I'm trying to get the rotary and another motor (same size thats in the rotary) to do the same thing. Is there an easy way of testing this (voltage meter, etc) w/o having to cut the harness and wire the second motor in? I don't want to fry anything.

Thanks
Trey

[Gary Hair]

Short answer is no. Longer answer is this - a stepper is controlled by a drive which gets its power from a power supply and control signals from the computer. For each stepper you must have a separate drive to interpret the signals from the computer and the power supply must be able to supply enough current to turn the steppers. You can't just "Y" connect two steppers together and have them work, that is about 99.99% sure to fry the drive and maybe the power supply.

[Trey Tull]

Thanks Gary. My idea was a little far out there but I thought I would ask first.

[Gary Hair]

Better that than to ask what the cost is to replace the board that got fried...

[Kev Williams]

I can only imagine why you'd need a second stepper, but since it seems they'd both be doing exactly the same thing at the same time, have you thought about the second 'stepper' being a passive unit? With some shaft stock, a couple of belt cogs and a belt, some bearings and some ingenuity to put it all together you could build a second rotary driven by the original stepper...

[Matt McCoy]

I'm not sure what you envision, but it's possible. Some hobby CNC machines, like the Shapeoko, can use terminal blocks to wire two stepper motors in a push/pull configuration to a single driver. This is an apples/oranges comparison with a proprietary laser controller, though, and probably wouldn't be recommended without Jedi hacker skills.

http://shapeoko.github.io/Docs/electronics.html

[Glen Monaghan]

It is highly unlikely that a manufacturer would go to the expense of installing a power supply that could source 2x the power required by the intended load (rotary stepper), so adding a second stepper in parallel with the first would almost certainly overload the driver circuit. However, you could add a high impedance buffer in parallel with the rotary stepper (or go into the driver circuit and tap directly into the logic-level step and direction signals) and use that to feed your own power supply and driver for the second stepper. In effect, you are parallelling the steppers, but without overloading the original power supply and driver. That sort of approach also frees you from the need to use an identical stepper for the second one. For example, the original stepper might be a 24V unit but you could use a 12V stepper. You could also implement a microstepping strategy if you could benefit from that (as a simple example, you could half-step the new motor once when the original driver switches from low to high, and half-step again when the original driver switches from high to low).