Stepper Motor Wiring (Screened?)

[John S]

Stick a meter on the cables and you'll find you are nowhere near 4.2 amps PER CABLE

Drivers are rated per phase, not per wire.

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[pequod]

Interesting point John. I'm new to stepper motors, so don't understand this. The motor I've ordered is 2 phase, 2.73V, 4.2A, 3.2mH, wired Bipolar Parallel, Zapp SY60STH86-30. I haven't got the kit yet to measure. So does this mean I rate the cable at 2.1 A? This could be good.

[irving2008]

Interesting point John. I'm new to stepper motors, so don't understand this. The motor I've ordered is 2 phase, 2.73V, 4.2A, 3.2mH, wired Bipolar Parallel, Zapp SY60STH86-30. I haven't got the kit yet to measure. So does this mean I rate the cable at 2.1 A? This could be good.

Each pair of wires is a phase... so a 4.2A phase on bipolar means 4.2A is being carried in 2 wires. In full step mode only 2 of the 4 wires at any one time is carrying 4.2A and not 100% of the time, but the maximum current in any one wire is 4.2A.

16/0.2 is rated for 3A continuous 6A peak in conduit, at 4A you will lose about a volt across a 1.5m length.

[John S]

I can't run a test because believe it or not I only have one small CNC running and it's hard to get to the motors on this one.

I can do later in the week but it is interesting to actually check just what power is pulled on a stepper system.

Geckodrive state that 2/3 of the maximum amperage of the motors is required so if you have a 6 amp motor they recommend 4 amps of power.
i know at one stage when we were doing the prototype X3 kits we worked out that we needed 4 x 2.5 amp = 10 amp divided by 2/3 so we arrived at a 7 amp power supply.

Once built running all 4 axis absolutely flat out drew just under 5 amps ???

So someone do me a favour and stick a test meter in circuit with one of the motor leads, most of the cheap multimeters will handle 10 amp, and tell us what the driver is set to and what it pulls on a rapid move and a low speed cutting move.

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