Hi folks !
Sorry for the crappy photo but I am trying to come up for a good wiring to connect E3D V6 hot end cables to ribbon cables (for tidiness, to have the plugable etc).
How would I determine the number of wires from the ribbon cable that are needed to provide the 12v (potentially 24v in a few months) at the amps needed for the hot end ? (without melting the wires & my home in the process).
The ribbon cable is this one : https://www.sparkfun.com/products/10647
I am REALLY bad at dealing with wire gauges etc so sorry in advances if any of this is very obvious.
Thanks in advance !
Heater cartridges are ~40W, so we can assume 4A @ 12V to be safe.
Your ribbon cable is 28 AWG, which according to http://www.powerstream.com/Wire_Size.htm can handle 1.4A each in free air before overheating. So three wires should be enough, but i’d pack an extra one in there for redundancy and reducing losses. Using wires next to each other will reduce their current capacity since they heat each other.
My limited research shows that the hotend can draw between 2.5 and 5.0 amperes. The same research suggests to limit the current in 28ga ribbon cable to 0.1 amperes, although other resources suggest as high as 1.4 amperes. If you wish to be conservative and have longer life of your ribbon cable, you would need a 50 conductor cable if your hot end draws 5 amps.
If you have larger ribbon cable, you can have more current. Some ribbon cables can be found with as large as 22ga, but you also have to consider the maximum capacity of the IDC connector used at each end.
I would suggest that you consider to investigate the type of connectors used for radio control aircraft and especially for radio control multi-rotor craft. They are designed to handle 35 amps and more at approximately 12v without problems. The connector engages with great security and are relatively inexpensive. If you have a hobby shop in your area, you can find two to five different types in stock.
@Thomas_Sanladerer wow thanks a lot , that is an amazingly clear and fast explanation !
" Using wires next to each other will reduce their current capacity since they heat each other." > so should I interleave or rather perhaps put 2 at each end of the ribbon (to reduce interference with the data wires ? (thermistors etc).
Also this is for a E3D chimera, so I guess I need to double up : 8 wires already + some extra for fans … hmm that is starting to be a lot of ribon cables
@Justin_Nesselrotte yes, theoretically. I’d still add an extra wire for redundancy, since you don’t want a single wire carrying everything if one of the two fails. @Mark_Moissette_ckaos if you’ve got data wires on the same cable or in close proximity, i’d still say go with an interleaved pattern (+, -, +, - …) on one end of the cable, then a real ground or two and then the data wires. Thermistors are super tolerant to interferences, though, as they naturally produce a very slow signal and are filtered on the board even further.
@Fred_U I always favor safety.
Do you mean some model of JST connectors ? I do have a few (short) one from quadcopters, but given the length of cable needed for my Delta printer, I would need to gear up
jst connectors are pretty low current capacity, often used in the tiny toys and other low draw flyers. You’d want something beefier. 4mm bullets are small profile and can handle more than a couple hundred watts easily. Deans ultra are common, as are EC3 and XT60. Another common choice for power connection is Anderson Power Poles. They have a housing molded in such a way as to engage each other, for an integrated appearance and the associated utility. I constructed a sensor cable to my EV battery pack using 8 in a row, while other connections used only two or three, but still a single block for all the wires.
@Thomas_Sanladerer I’ve done research specifically on ribbon cables, and the 28AWG ones are only rated for about 1A each, at least when adjacent lines are carrying current, so you want at least 4 for a heater cartridge. On the Bukito, we used 5 each direction.
There are also some 26AWG ribbon cables that maintain the .05" pitch, while being able to handle a little more current, but the better solution is to use Cicoil high-flex ribbon cables. Not only is high-flex better for this application, but the the silicone insulation can also handle higher temperatures. The ratings say 5A per conductor, though I’d still probably use a pair to get some safety margin (even if the wires themselves are rated for it, I doubt the connectors are). http://www.cicoil.com/flat-cable/unshielded-cables/hi-flex-hi-temp-idc-ribbon-flat-cable-8-1/
@Thomas_Sanladerer ok, thanks interesting pattern!
I really thought the thermistors close by were going to be an issue , so that is good news!
@Fred_U Ah ok , I have some spare XT60 & Anderson Power Poles as well . I REALLY do wish I had some “daugter-boards” close to the hot-end for the electronics of the reprap, it would make much more sense to only have to bring ONE set of 12v power cables, and then only logic cable from the main electronics …
@Whosa_whatsis Neat !
would that type of cable also what you would go with for your "standardised connectors " project ?
If breaking due to flex is a factor to be addressed, the radio control community can once again contribute. I’ve purchased heavy gauge silicone insulated wiring that is specifically engineered to be flexible. The key aspect of such wiring is that the conductor is composed of many small diameter strands, rather than a few large ones.
Remember that the hot end only pulls max current when it’s initially heating up. This is a short duration and the ribbon cable can handle this just fine. Mine runs 3 wires each for + & - (6 total) and does not have any overheating problems.
That said, it is probably best to run RC wire to the hot end and heated bed (good silicone wire) It’s relatively cheap.
For the hotbed, I would never use a ribbon cable. The heated beds typically draw close to their rated current for extended periods. This can overheat the cable (especially a slightly worn connector).
Ribbon cables are pretty and all, but I am in favor of running the appropriate wire for each individual thing and then using wrap to bundle it neatly. If that appropriate wire is 28awg then sure use a ribbon - if its 16awg use 16awg.
I’m with Doug, CSA and electrical standards never suggest coupling smaller wires to get 12 gauge, it’s simply nonstandard.
Meaning always plan catastrophic failure, that it has been tested for. It’s an insurance thing.
I asked electrician advice on 20amp, always stay with rated and association tested setup. Am a welder of trade.
@Fred_Baumgartner interesting ! do you have some pictures/write up for your setup ?
I only wanted to use ribbon cables for the hot end(s), I agree that for the heated bed, that would be crazy ! I only have the two wires, and only 10 cm max between the electronics and the heated bed , so requirements are not the same
@Doug_Rector & @JC_Ouellet I agree with you on the need to run adapted cables, but it is not a question of “prettiness” at all , but of practicality: most importantly for the connecting of cables , not so much the cabling itself : I am more than willing to look into alternative solutions : , also the fact is , I tried running the 13 + cables I need for the hot ends + cooling from the electronics to the effector , and it is a goddam mess to deal with , wrapped or not
I do not want to sacrifice security , but I really hate screw connectors to deal with such a huge number of cables. So if you have solutions on that end, please post
@Mark_Moissette_ckaos I don’t have any photos handy and it’s not 3d printing related, only connector related. Pretty much standard power pole joining, one bunch of two conductor, and a handful of ten, if I remember correctly, to pull “signal” lines out for an EV battery pack. An absolute spider web of wires but hidden in the battery bay, not out and visible as it would be in a printer. Even with that in mind, you should be able to use a single pair of properly sized silicone insulated wires for your hot end and not add excessive mass. It’s more likely that the equivalent number of small gauge wires is going to add more mass via the insulation for each conductor.
@Fred_U so something like these ? seems interesting indeed
The mass is not something I worry about at all to be honest It really comes down to tidiness, being able to plug/unplug easilly and avoid too many different cable types
Thanks for the feedback !
@Mark_Moissette_ckaos It appears that you have found a power distribution block, which isn’t what I had considered, but it’s a good way to have more than one location to connect.
Power Pole connectors have a reputation of being easily connected and disconnected, yet able to maintain a quality connection after many cycles. They are used on high draw devices like fork trucks, electric vehicles and electric assist bicycles. The ones in the photo are good for 15-50 amps, while others are much larger and capable of hundreds of amps.
Many RC type connectors have a reputation of being difficult to to disengage, and I’ve experienced just that with connectors for my model planes.
german electrical-engineer here, give me some more info and I will do the math for you. Tell me the power of your desired heater-cartridge (40W?), the voltage of your system and the length of the wire from Board to Hotend,
