Twisting wires not always needed?

I am looking at build guides for RAMPS based systems, pictures of RAMPS systems and pre-made wiring kits for RAMPS systems. The guides I have found so far and the pictures I have seen do not seems to call for/show twisting the stepper motor wires in pairs as the Mendel90 build manual has.

If twisting the wires is necessary how are they getting away without doing so?

And even stepper motors with connectors already attached don't have twisted wires: Stepper Wires not Twisted

Edited 1 time(s). Last edit at 06/12/2014 03:16PM by Garry Bartsch.

Do those systems run other wires parallel to and in close proximity to the stepper motor wires? If they don't then it doesn't matter, since the aim of twisting is to reduce the induced current in signal-carrying wires nearby.

Never even heard of such a thing being need or that being why some wires are twisted..
Goes to show it doesn't make a general difference. I'm sure there are times and places where it will, though.

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Twisting the wires makes shore there is not a big gap between the two wires. If there is no gap then the magnetic fields around the two wires will cancel each other out.... If you dont do this and leave the wires flapping around in the breeze with a big gap between the two wires a big magnetic field will be produced. As the current in the wires is changing lots the magnetic field will be changing quickly. That is how a radio transmitter works... a wire with a fast changing current in it. So your machine will work just fine... but the next door family will wonder why there TV reception just got worse.

Its not good to go around creating unplanned radio transmitters... it just takes a bit of twisting to make the problem go away.

Edited 2 time(s). Last edit at 06/12/2014 07:57PM by ElectroWomble.

Most texts describing the use of twisted pair concentrate on its use as a means to reduce the effect of external noise on a signal. This is particularly of benefit to differential signalling where common-mode noise can be removed at the receiver.

In the case of stepper motor wiring we are not dealing with received signals but this method can be applied to reduce emissions. The logic here is that the electromagnetic fields generated in the wires are opposing (due to current flow being in opposite directions) and the twist results in the fields cancelling each other.

Nophead's suggestion that all wire pairs on the Mendel90 are twisted is simply good engineering practice. There is an old saying that goes "Why spoil the ship for a half-penny of tar?". I believe it applies to this case.

Regards,
Neil Darlow

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Thanks all. The information you give is just what I needed. I want to build machines with as few weak links as possible. I will definitely twist the pairs in any future builds.

An old thread but I wonder if the new TMC 2130 chips that use current monitoring mean that they are more susceptable to noise? I'm just coming up to speed with my first printer using the Watterott silentsteps and I'm thinking of twisting the pairs.