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Cable management bad magnetic field or induction??? Or anything?confused smiley

Posted by Bobyni 
Cable management bad magnetic field or induction??? Or anything?confused smiley
November 14, 2015 05:27PM
Just wanted to know, what are the impacts (if any) when we bundle up all the cables that a 3 d printer has.....
Does it cause signals to be noisy?
Dies it cause print imperfection?
Does it cause anything at all?

I hope if you know something could share it with me/ us/ the community...
Thanks in advance!

Edited 2 time(s). Last edit at 11/14/2015 05:28PM by Bobyni.
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 14, 2015 07:46PM
I had to deal with this in my printer early on. It was a pain to find.
The printer would do random resets, particularly when a retract happened.

As I was exploring all possible causes, I shielded all my stepper cables as recommended here, all except the extruder's wires...

It turned out I had one particular particular wire running perpendicular to those extruder wires. That one wire was going to a reset button I had installed. It would decide to get a reset signal from that extruder at some random time during a 12 hour print...

Stepper motor wires are NOISY, because of the high inductive loads.

It is recommended to keep the stepper output cables as far away from any signal cable as possible - for instance: thermistor wiring, reset switch wires...

The heated bed wiring is also a potential issue, as heavy currents are being switched rapidly.

Having a wire running perpendicular to another wire is the best case for keeping them isolated, but you still do not want them close if one is noisy.

The other wires can be bundled.

Hope that helps!


My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 15, 2015 10:23AM
Hi Paul! Thanks for your feedback!!!!
That would explain what I have oscillation on my Temp from hot bed while printing!
I have suspected and you confirmed it!
Thanks!
I will re do all my cable and see how it goes.
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 15, 2015 10:33AM
You're welcome.
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 15, 2015 11:00AM
It's a good idea to twist current carrying wires into pairs. The twist helps organize the wires and helps control stray magnetic fields created by the current running in the wire. You can easily twist wires into pairs by clamping one end of a pair in a vise and putting the other end in the chuck of an electric drill. Pull the wires taut then run the drill while keeping some tension on the wires. You'll end up with beautifully twisted wires in a jiffy.

I like to braid the twisted pairs and single wires to help keep them organized, too. If you braid them you won't need external jacketing or loom. Of course, if you braid them, making changes later can be a little troublesome, but no more so than if you used loom or a jacket. It only takes a few minutes to braid them- clamp one in in a vise and manually do the braiding. There are a lot of web sites/videos that demonatrate how to braid any number of wires/cords.

Here's the X axis cabling in my printer- the colored wires are for the motor coils and the white wires are for the X minimum limit switch. Each coil has its own twisted pair.



Edited 2 time(s). Last edit at 11/15/2015 11:04AM by the_digital_dentist.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 15, 2015 01:36PM
DD!
Thanks!!
It is always a pleasure to
read your feedback!!!
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 16, 2015 06:18AM
The method of braiding the cables together used by the_digital_dentist has some additional advantages:
  • As there is a twisting component on the wires a braided bunch is more flexible than putting them in a sleeve or tying them together with cable ties or string.
  • The noise performance is as good as twisted pair cable. Wires intended for picking up very low level signals (e.g. electrocardiograph) are frequently braided together for this reason
As an additional advantage, if you run a superelastic wire such as Nitinol through the bunch of wires it becomes self supporting. as shown below.

Nitinol wire is visible in the bunch or wires
Mike

Edited 1 time(s). Last edit at 11/16/2015 06:23AM by leadinglights.
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 16, 2015 06:45AM
There are two sorts of crosstalk you can get between electrical wires:

1. Magnetic induction. A cable carrying a current that varies rapidly (even if only occasionally) generates a magnetic field, which can be coupled to another cable. For example, a stepper motor or bed heater cable could induce a voltage in an endstop switch cable. Minimise this be making sure that the outgoing and return conductors carrying the current are as close together as possible (i.e. in the same multicore cable), and preferably twisting them together. Similarly for the signal and ground connections of the endstop switch circuit.

2. Capacitive coupling. A cable carrying a varying voltage runs close to a signal cable with a high impedance input, and the capacitance between the cables gives rise to a voltage on the signal cable. Minimise this by shielding one or both cables (independently), or keeping them away from each other, or avoiding high impedance signal inputs.

The problem the OP had was almost certainly caused by capacitive coupling.

These types of coupling have a bearing on whether you use NO or NC endstop switches. If you use NO switches and printer electronics with a high impedance input (e.g. RAMPS or RADDS), then you are at the mercy of capacitive coupling and you had better use shielded cable for the endstop switch cables. OTOH if you use NC switches then capacitive coupling is unlikely to be a problem. Inductive coupling could still be a problem; so use one multicore cable for the stepper motor and a separate twin core cable (or twisted pair) for the endstop switch.


Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet.
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 17, 2015 12:02AM
Thanks Dc42!!
Thanks leading light!
When knowledge people post, it is a pleasure to read through and get more "education" from!

Really enjoy all the post so far!
And definitely re doing my cables!
smileys with beer
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 17, 2015 02:27PM
Quote
digital dentist
It's a good idea to twist current carrying wires into pairs.

are there any rules how to choose the paires to twist eg only the A coil and only the B coil or one wire from A with one wire from B
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 17, 2015 04:48PM
Quote
sungod3k
are there any rules how to choose the paires to twist eg only the A coil and only the B coil or one wire from A with one wire from B

If you are going to twist them, use a separate twisted pair for each coil.


Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet.
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 17, 2015 06:56PM
Quote
dc42
Quote
sungod3k
are there any rules how to choose the paires to twist eg only the A coil and only the B coil or one wire from A with one wire from B

If you are going to twist them, use a separate twisted pair for each coil.

To elaborate on this a little, think about what is happening when you twist the wires connected to one motor coil around each other. By twisting, you turned the wires into coils. Think about the current in one of the wires. A current in a coil produces a magnetic field that remains largely within the confines of the coil, until it escapes at the ends. With two wires twisted around each other, the currents move in opposite directions, so the magnet fields created are equal and opposite, thereby canceling each other out and greatly reducing the tendency for the twisted pair to induce noise in adjacent wires. Of course, it isn't perfect and there will always be leakage of the magnetic flux, especially at bends in the cable, but it works well enough.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 17, 2015 10:19PM
Aha that makes sense. Ill try that next time I rewire my machine.

I only had problems with the thermistor wires once and changed them into shielded ones,after that it worked normal.
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
November 17, 2015 10:30PM
Shielding prevents capacitive coupling but does nothing to prevent inductive coupling.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
December 06, 2015 09:04PM
Thanks.

Ferrite core


Ferrite beads

Re: Cable management bad magnetic field or induction??? Or anything?confused smiley
December 07, 2015 12:57AM
Thanks janpenguin for the nice pictures of ferrite
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