What wire to use to hook up motors to driver boards

[dennisyuki]

I am building a desktop CNC 12"x8" and I bought a 3-axis kit from probotix which I am about to set it up. I have been trying to find a local supplier for wire to hook up my motors. I have read people using 22 awg wire. Should I use 22 awg or go with 18 awg.

I saw Lowes at one time sold 22/4 and 18/4 stranded wire for alarm systems. would this wire be good? would it support the 2 amps from the drivers to the motors?

If no local suppliers. where is the best place to 22 or 18 awh , 6 conductor stranded, shielded wire?

what size wire should I use from my 24V power supply to the driver boards? 22Awg?

Thanks for the help in advance.

[brtech]

I think you should use 20 ga. 18 is better, but 20 is okay. 22 is too small.

I'd use 14 ga stranded from the power supply to the board if you are using one pair. Two 18 ga would be okay, or 4 x 20 ga.

Finding 3 pair 20 ga shielded isn't going to be easy. I'm not sure you need to shield the wire for this application. It's good, but not really necessary. I'd worry more about home/limit switch wire than the motor drive wire for shielding.

[ger21]

22 awg should be fine. I've been using it on my machine for a few years.

I think that all the Nema 23 motors that keling sells have 22awg wire leads attached. Even the 570 oz motors.

[TarHeelTom]

Here's a place I buy a lot of wire.

http://stores.ebay.com/Johns-Silver-Teflon-Wire-Shop

If you don't find what you need, drop him an email.

Although he has standard lengths on the site, he'll cut you any length you want.

Nice guy to work with.

Tom

[dennisyuki]

Thanks for all the input. I think that helps point me in the right direction.

[AssassinXCV]

I got 22awg 6channel wire for my cnc.

[Walky]

After some researching I decided to use 22AWG with 400oz-in steppers at 2.5A and 42V and it seems to be ok, been using them for more than a year.

AFAIK, AWG current ratings are very overrated (for a reason, though).

[brtech]

Wire gauge translates to resistance PER FOOT. The shorter the wire, the less resistance for a given gauge. There are inductive effects, but a 6" pigtail of 22 ga is not the same thing as a 15' cable of 22 ga.

22 ga is about .16 ohms per foot. 20 ga is about .1 ohms per foot. If your cables are 3', the difference isn't likely to matter much. If they are 15', it may.

I'll stand by my recommendations. A smaller gauge will "work", but you might lose some power. How much? Hard to say. This is a small system, right, 24V, 3A or so per motor? I squared is 9, so you lose .9 watts per foot with 20 ga, 1.7W/ft with 22 ga
The motor is 3*24 = 72 watts give or take.

[RomanLini]

22GA is rated at 7A absolute max and 16 ohms per THOUSAND foot. That's 0.016 ohms/foot.
20GA is rated at 11A absolute max and 10 ohms per thousand foot.
18GA is rated at 16A absolute max and 6 ohms per thousand foot.

20GA is about optimal but there is no reason you could not use 22GA for your 2amp motor wiring.

Possibly the best way to choose motor wires is based on the quality, flexibility (more conductors total, finer conductors) and a reasonably thick insulation.

Brtech- sorry to be argumentative but your ohms per foot was 10x out, and also as stepper motor drivers are closed-loop current regulators they will maintain the same motor current regardless of ohmic losses in the motor cables. So technically there is no difference in performance between say 20GA and 22GA cables for 2 amp motors.

If you wanted to calculate losses due to wiring resistance it would act as a reduction in the PSU voltage, so with 40 feet total of 22GA cable it has 0.006*40 or 0.24 ohms worse than 20GA cable. For 2 amp motors that 0.24 ohms will be seen as a PSU drop of about 0.5v. I'm not sure you would tell any difference between a 24v PSU and a 23.5v PSU in terms of motor performance.