Hi guys, I just purchased an e3d hotend for my Mendel and I have been thinking about cable management from the hotend to the PCB. I think it would be a good idea to use something like a Cat5 breakoutboard that would be mounted to the X carriage and on the back of the PCB board. A simple Cat5 cable, maybe a flat one from monoprice would then easily connect the two.
What are your thoughts? Anyone try something similar and want to share?
Yep, 3A is probably too high. I use IDC twisted pair stuff for thermistors, endstops etc but steppers and heaters will likely be too high current, there will be a chance of shorting across the contacts or possibly inductive cross talk to other pairs.
Those flat cables are going to be even worse than regular rigid cat5, which is, after all, just 8 strands of AWG24 solid core. You can double up sufficient real cat5 strands to get your current capacity, but it would be awful in many ways.
Great to see someone else approaching that problem.
I did something similar because I wanted my extruders to be pluggable. Therefore I took a 10 lane AWG26 ribbon cable with its convenient crimp connectors. For the hot end I joined twice two lanes together. The AWG26 supports 1.5A per lane - together they do 3A. The wiring is like this:
Pin 1+2: Hotend
Pin 3: Stepper 1B
Pin 4: Stepper 1A
Pin 5: Thermistor
Pin 6: Thermistor
Pin 7: Stepper 2A
Pin 8: Stepper 2B
Pin 9+10: Hotend
This way it does not do any damage if plugged in wrong.
Going that close to the max ratings of a ribbon cable would worry me – you kind of want no more than half or a quarter of the max rating under regular use. Especially if you use off-brand copies of connectors and wires, of course, as many people will be.
Not to mention: what is the resistance across that cable and connectors? How much voltage are you dropping in it?
Anyone know type of ribbon the mendel90 uses? I wouldn’t be too worried about the cable, rather the rj45 connector, they just weren’t designed to take those sort of currents.
I’m using UTP Cat5 wiring all over my bot - each stepper coil (as much current as the drivers can handle) gets a pair, the hotend (E3D) gets two, and you can’t even feel the wiring getting warm at all. I’m not using RJ45 connectors, though, i just solder the wires to pin headers and use those as connectors (i know, ít’s not a nice solution, but it’s cheap, easy and works).
@Jasper_Janssen
For what its worth cat-5 can be purchased in stranded form which makes it more durable but id definately doesn’t answer the current issue.
I saw on the Mendel 90 it uses DB15 connectors and ribbion cable. Looks good and has more IO than than Cat5 which would be able to easily support multiple extruders. Think I’ll go that route.
I’m not as young as I used to be and that will be obvious when I make this suggestion. What about classic D connectors like those used in serial/parallel/vga ports. They could handle more current and plug nicely. You could even use the screw to secure/remove the connection quickly. I know its old-school but it should work nicely without going into much more expensive connectors. You do have to enjoy soldering wires into pins and then inserting them into the connector but you can meet your current needs that way. A high density 15 pin VGA connector is actually pretty small and you could double/tripple/… some up for heavy current. Stuff like this: http://stores.ebay.com/partsparadiseinc/DB25-DB9-Cables-Adapters-/_i.html?_fsub=4244663&_sid=123506999&_trksid=p4634.c0.m322
@Rustin_L_Haase I first thougt about D connectors as well but imho they are too large. I needed two oft them for a dual extruder and got a space problem. My favorites would be sata power connectors: 12 lanes, easy plugging and capable oft quite some current. But I was not able to find some male / female for soldering.
@Muccaneer_von_Munche actually, Sata power is 15 spring contacts but only 5 connections (three voltages, two grounds, normally). I’ve never seen a connector that breaks out the individual contacts.
The Cat5 cable will do the job nicely. Just keep in mind that you will need to use multiple conductors to carry that much current. Look at the power over Ethernet spec if you are curious or just parallel up 4 conductors and you will be fine. Get stranded cable so the continuous flexing will not be a problem.
