So I started a discussion with @Rikard_Hamrin about cabling and decided I make new post here so everybody can contribute.
My idea was to use network cables for the cabling of a 3D printer. In my case I have a delta and will need to connect two extruders, two hotends, three end stops, two fans etc. So I do not intend to connect heat bed with that cable (I have anyway a 220V heat bed).
Also I want use network plugs and connectors to connect everything.
What I found until now is that network cables seem to be fine but the connectors may be not good for higher Amperages and may fail over time. But I could not find info, which is 100% as I also found other info.
Now Rikard said, that he thinks that the network cables are not good for the Amperage.
My plan was to use more than one connection for each high Amp device. That means that all 8 lines in one network cable for a stepper and at least 4 lines for the hot end.
Is here anybody with knowledge to say for sure that this will work (not would, not maybe)? I just want to make it right and have rock solid system.
Research the specs for the leads in the cable and the connectors. Take not only diameter into account but also number of cores - single core AWG24 has other current ratings than eg 3-6 core or more. Compare with maximum amperage you are going to send through, plus a generous safety margin.
This is nothing that should be discussed but researched properly. And don’t take anyone’s word for it, it’s your house burning down if you get told something wrong and rely on that, your responsibility to use adequate wiring, connectors etc.
That being said, network patch cable, as already pointed out, is used for data transmission. It’s optimized for that use case. Yes, power over Ethernet is a thing, but not in the context of stepper pulses which create electro magnetic interference and also not for applications that involve the cable getting straightened and bent all the time, thus increasing expected wear tremendously. Broken core in the cable with same amperage => burning cable. Considering that, no, I don’t think it should be used for wiring anything on a printer but maybe Ethernet for an included webcam…
There was a big argument about this here last week. The cables are probably fine for a NEMA 17, particularly if you double up conductors. Yes, the Cat5 cable current rating is nominally quite low, but that limit is intended for bundled in-wall applications where cable heating must be kept to a bare minimum. The bigger issue is connectors… They are typically only rated 1.5-2A under ideal conditions and a stepper’s average current through the connector is ~2.8x the nominal current per coil. (Two coils, two ways per coil, times 0.7 to convert peak to RMS.) So you’re limited to low-current steppers.
It’s been done, and it works if you bundle up enough leads to handle the watts you are putting through it.
I have personally used cat leads for endstops and thermistors and they work just fine. (It’s just a cable after all).
But I’m with @foosel and @Ryan_Carlyle in this, I do not believe cat cable and connectors are the proper (“rock solid”) choice for motors and extruder heater.
And what would happen if you accidentally switch two connectors when fiddling with something? Very bad shorts if you haven’t thought out the cabling extremely well… Also cat connectors are bulky.
I would go for simple screw connectors, eventually with a ferrule on the end of a properly sized cable, which is colour coded to avoid connecting it wrong.
@Alex_Skoruppa yes I heard that statement numerous times as well as the opposite also numerous times. I would like to get a technical explanation for the reason that it will work (and is on the safe side) or not work. And what about network connectors? Can they also work with the hot end and steppers?
@foosel that is exactly what I am trying to find out: what would for sure work? As I do not have the knowledge, I am asking.
I was anyway thinking of using network installation cable, which is more thick. But also only for the parts on my delta printer, wher it goes up the posts. On both sides will be connectors.
What I am really puzzled is that original cables of my delta are just ribbon cables, which had been stuffed into the extrusion. These cables are more thin and I think that was more dangerous.
Anyway I was thinking of using some connector, which has 2x8 connections or something like this. Or a distribution board with individual connectors and caption.
@Hakan_Evirgen what I was trying to tell you is, you are literally playing with fire here. If you do not have the knowledge, you either need to change that (by doing the necessary research and calculations) or don’t do it at all. Nobody here knows your specific setup, so when someone tells you it worked for them that doesn’t mean it will work for you, so you need to figure it out for yourself, that is your responsibility. People can hint you at whether it might or might not work, but the final say is your’s and for that you have to do the legwork.
And “not working” in this case does not necessarily stay at “nothing happens” but can rather lead to actual damage through electrical fires - in case of long term material failure due to the cabling not being adequate to the mechanical stresses that can also happen way down the road, so it simply working fine at first doesn’t mean it will in the long run either.
We just had an article shared around here the other day with yet another printer that nearly ignited a house because the operator made a big mistake. So, if you want to tinker around with electrical wiring, make sure you can with absolute certainty decide yourself whether it is safe or not what you are doing. If you can’t, don’t.
Look at it like this: how do you think anybody here would feel if they told you it works fine for them, you did something slightly different than them and your printer went up in flames as a consequence?
@Hakan_Evirgen The reason that it’s not advisable is the wire is too small to handle the current without combining conductors. Combining conductors is not an accepted method of increasing current capacity. Were one conductor or connector pin to fail to load would be shifted to the remaining conductor(s) resulting in a potential over load. As stated by others RJ45 connectors aren’t rated for that sort of duty cycle. In addition to that, when using multiple conductors in a single jacket for power transmission the entire cable is derated based on the current capacity and/or design depending on the number of conductors.
IOW, what may be a 4 amp single conductor cable is derated when bundled in a multicore depending on the number of conductors bundled. That means six, 4 amp conductors do not add to provide 24 amps in a mulitcore. Depending on the application it could be as low as 16 amps. Modern power over ethernet is typically in the milliamps, or at least under an amp. It’s closer to 400-600 mA at 5 volts.
When designing something like this cable assembly it’s important to have this basic knowledge…
Understand the application and topology the circuit that the cable assembly will service. This includes current draw and voltage in both idle and high duty cycle applications. This includes the basics of Ohm’s Law, the relationship of current to voltage. If one does not know Ohm’s Law, they aren’t qualified to be doing any of these designs or calculations.
Understand the design parameters of the cable assembly and the operating environment. Does it flex, is it subjected to environmental factors, are there any mechancial constraints?
Knowledge of the suitability of prospective components. Are they used in similar designs? Do they have the necessary capability not only electrically but also mechanically?
@Hakan_Evirgen there are several types of network cable, but they can be divided into two groups of two, firstly there is shielded or non shielded cable, non shielded being the most common, then these groups are divided into solid core or stranded conductors, the typical use case is that solid core conductors are run in fixed locations, such as from a cabinet to a wall plug (the cable is put in place and not moved), stranded cable is used to connect from the wall plug to a device, typically a computer (the cable is expected to undergo some flexing over time).
shielded cable is used in environments where noise is an issue, and the shield is grounded at only one end of the cable.
As far as power capacity IEEE standard 802.3af allows 13 watts delivered using 4 wires two for positive and two for negative.
IEEE 802.3at allows 25.5 watts.
I would suggest reading both these standards to understand the configuration for using power in Cat 5x - 6 cables.
Keep in mind that the cables are not really designed for environments where they will be flexed regularly, and POE devices generally have a means to detect a broken wire and shut power off to avoid fires, lastly as stated because you will need to bundle wires to carry sufficient current, any broken wires will significantly increase the chance of fire, and using Murphy’s law the fire will happen when the printer is unattended.
I see no problem using Cat cable for signals such as thermistors or end stops, but extruders, beds, and most likely motors are exceeding the safety limits of network cables.
If you want to use them and they work for you go right ahead, it is entirely your choice and responsibility, but ask for advice (which you have done) and then do your own research before deciding.
There are many connector types out there. It is better to choose an appropriate connector for the intended application than to make use of something just because it is at hand.
I think @foosel is right, you are taking a huge risk with those connectors. They are not designed for high current. Cat-cable should be no problem, I’m using it for my big printer for more than a year, and my steppers are taking up to 2,5 Amps. I do use 2 wires for each connection though. I would certainly not recommend this cabling for a hotend or heated bed. And I use screw connectors for everything.
The reason I use cat5 for steppers, is that I want shielded cables, and can’t find anything out there that is shielded, supple, and thin enough for my cable-chain.
I’m by no means en expert in this field, far from it.
What I did was use a simple DC current calculator to determine the cable needed for my hotend et.c. Like this one; http://www.solar-wind.co.uk/cable-sizing-DC-cables.html
I’m not going to discuss network cables as I have no direct experience. I will talk about using multiconductor cables for use in 3d printers.
The Rigidbot uses ribbon cables to supply power and signals to and from the extruder/hotend and also for the heated bed. Our google group has well over 2000 members and we have seen over and over and over again melted and burned cables. What happens is the ribbon cable and connector can handle the current by using mutiple wires for both V+ and Gnd. The problem is that over time one connector pin will get a little loose or oxidize a little and lose current capacity. That causes the other pins to carry more current than they are rated for; the other pins begin to overheat and oxidize and lose current capacity. This cascade of events escalate rather quickly resulting in melted and burned connectors/cables, shorted power and signal leads, burned out thermistors, and fried controller boards. One of the most popular upgrades for the Rigidbot is replacing the heated bed ribbon cable with heavy gage silicone wire - one conductor for V+ and one for Gnd. Thermistor signals are carried by separate wires.
Using multiple wires to carry power and ground is dangerous to both your printer and your house. If you are intent on following this path, please take appropriate precautions such as placing your printer on an absolutely fire-proof surface such as tile or concrete and at a minimum, install a smoke alarm near the printer. 3d printer safety is no joke, done wrong they can be dangerous.
I think I can use network cables for everything except hot end, heat bed and steppers. Still need to go through the planning - thanks to all for the links pointing me to the information how to calculate and get more information to understand what is necessary.
Avoid the solid core wire used for in the wall runs. Period. Excessive handling during a normal install can cause the conductors to break or change shape enough to cause data errors. Using them to connect moving axis will cause them to break. Bad enough losing an endstop, forget about heater.
Additionally I have concerns about using cat-* near the heater. Cat-* wiring is not rated for those temps, and will release toxic smoke (unless plenum rated) if it gets hot enough. There is reason hotends are connected using high temp wires.
I’m left wondering why consider cat-* when there are so many better options available?
@Matthew_Simicsak I am not intending to use these cable near hot areas or moving areas. I will use them to connect the bottom of my delta printer (where the electronics is) to the top of the printer. On the top there will be connectors where you connect the hot end etc. with their own cables.