wire question

[scrambled]

Hi everyone,

I am in the process of building a CNC plasma cutter. I have started to order all of the electronics that I need, but I now have a generic wiring question.

For my break out board, I ordered a C23 from CNC4PC. According to the website, this BOB is fully optio isolated.

So what does that mean? I am starting to install the e-stop switches, temporary stop button, limit switches, and restart button. I have all the boxes and switches mounted and it is time to choose what type of wire to use.

I have several hundred feet of 17 conductor wire in 1 bundle. This would make installation a snap, but I am not sure if this would be good to use since it is not shielded.

Any ideas or suggestions? Or should I just bite the bullet and order shielded cable. If this is the case, what size should I get and how many conductors?


Thanks for the help



Steve

[Crevice Reamer]

Hi Steve!

You can use THIS wire for motor cables and home/limit switches. Ground the drain wire ONLY at the driver end.

http://cgi.ebay.com/Servo-Motor-Wire...3286.m20.l1116

These gold-pin connectors are good and fairly cheap:

http://cgi.ebay.com/CNC-STEPPER-MOTO...713.m153.l1262

If you don't already HAVE them, these are excellent home switches:

http://cgi.ebay.com/6-CNC-LIMIT-SWIT...742.m153.l1262

They are NO, so only for home switches. Limit switches need to be NC. the whole set of 6 switches costs less than ONE switch would cost at Radio Shack.

CR.

[scrambled]

CR-

Do you think shielded for everything is the way to go? even the I/O?

Two of my servo motors are 1125 OZ motors. I need to figure out what size wire those need.



Steve

[Crevice Reamer]

Shielding NECESSARY for home/limit switches and encoders. These are affected detrimentally by crosstalk. Shielding DESIRABLE for motor cables. Shielding NOT needed anywhere else.

What is the amp draw of your motors? 18 AWG wire will handle 16-23 Amps.

CR.

[Crevice Reamer]

Optoisolation means that nothing is directly connected to your computer. So if your BOB or something suffers a direct short--nothing in the computer will be fried through the parallel port. This is something that you really want.

This is accomplished by translating the signals into light flashes and then reading the light with optical sensors--hence optoisolation.

CR.

[scrambled]

Cr-

Thanks for the help!

The motors I am using are rated for 7.8 continious, and a peek for 40 amps. So should i size the wire for peak or continious?

Here is the motor
http://kelinginc.net/KL34-180-90.pdf

Thanks again



Steve

[Crevice Reamer]

Sorry! I should have asked: What amperage is your DRIVER restricted to? That will determin max amps through the cable.

CR.

[scrambled]

Cr-

the driver is 14A cont. 40A peak output for brush DC motors

Do you know if they make 8 conductor shielded cable? I just hate to run several cables from one box to a second box. There is a bigger chance to wire it wrong.


Steve

[Crevice Reamer]

I can't imagine that you will need any heavier wire than 18 gauge. As for the Eight wire, That will get expensive. You would need twisted pair wire with each pair shielded as well as totally shielded around ALL wires.

You do NOT want to run unshielded motor wires with unshielded encoder wires or unshielded home/limit switch wires.

You are better off to use the individual pair shielded wire I recommended, and bundle the wires into a cable.

CR.