Really depends on what you're deeper goals are. For a "real" machine (read:
production oriented, 24x7 operation, downtime costs big $$$) you want
something called "continuous flex" cable. I have some experience with Igus
brand chainflex cables. Very good cable, but quite expensive. Either way,
their website is a valuable source of information regarding motion cabling
- http://www.igus.com
With good design and proper cable carriers, their cable can give you 10s of
millions of cycles - but that costs upwards of 5$US per foot, plus the
carriers.

In a more "hobby" situation I've had pretty good success with just using a
good design and everyday wire. A few... well, I can't call them "rules of
thumb", let's call them "suggestions"

Smaller cable flexes better than larger cables -> consider paralleling
multiple conductors, and possibly single strands instead of a jacketed
multistrand
Arrange for the largest bend radius possible. Consider 10x the cable radius
a minimum, 20x is better, diminishing returns above that. Improvement
between 30x and 40x probably not measurable in a real-world situation.
Try to keep the flexing on one axis if at all possible.
Avoid axial twisting. Better to arrange a couple loops to behave like a
clockspring.
Secure the ends of the flex section very well.
Make sure you don't flex it right at the securing point
Make sure the cable is longer than necessary, don't let the machine axis
"tug" at the securing points.
Support the cable.


I've had good luck just hanging the wire so it forms a largish "U" shape.
(Google "festoon cable" for ideas)
In shorter runs where hanging wasn't an option I've tied the cable to a
small carbon-fiber rod. (other flexible stick options also possible)
essentially it becomes a supported upside-down "U".
It's not shielded, but (at least where I live) you can get 4 conductor flat
ribbon cable for automotive trailer lights. Googling.... Here's an example.
http://www.waytekwire.com/item/WP14-4/14-GA-4-CONDUCTOR-PARALLEL/  Being
flat it has a much better bending radius in one direction. Usually
available at auto parts stores, I've seen it at Walmart.

The RepRap crowd has taken this idea and run with it.
http://reprap.org/wiki/File:Mendel90-front.JPG It's using typical computer
ribbon cable, flexing in the thin orientation and supporting it with a
strip of thin plastic - paralleling conductors for more current capacity
where necessary. As to their cycle life... a single build can contain
upwards of 40k cycles on the X axis. They're doing dozens or hundreds of
parts without failures.

-Denny




On Thu, Oct 3, 2013 at 3:39 AM, Luis Moreira <
luis.moreira1575@googlemail.com> wrote:

> Hi Guys,
> A friend as bought a table top CNC Machine, actually of a very good
> quality, mechanically. The only thing that lets it down is the quality of
> the cables used from the controllers to the motors.
> I am looking for a good quality four core .75 or 1mm overall screened cab=
le
> which as to be flexible enough to go on the runners back and forwards wit=
h
> the axis carriers. Ideally something I can get from Farnell or RS would b=
e
> great.  Any recomendations welcomed.
> Many thanks
>             Luis
> --
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