Extruder Cable
Posted by the_digital_dentist
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Extruder Cable September 14, 2016 03:51PM |
In my experience, wiring the extruder carriage is one of the biggest PITAs in 3D printer design/construction. There are a lot of wires carrying different signals/voltages/currents, the cable has to be very flexible and able to withstand a lot of flexing over the life of the printer, and should be easy to connect/disconnect for service, at least at the extruder end. In my own printer I went through multiple connectors and cables and found that even using a multipin connector wasn't ideal because of the bulk and the fact the wires had to be soldered to it making some extruder maintenance inconvenient. I had one cable fail after using a cable chain with too small a bending radius.
I eventually settled on a cable I found in a junk pile at the makerspace. It is a flat flex cable from a tape library robot. The original cable had two ribbons with 17 conductors and 34 pin double row header sockets on each end. I didn't need so many conductors, so I carefully split both the cables and connectors length-wise and ended up with two 16 conductor cables. I have been using one on my printer for 2+ years and it has performed perfectly. I added small, hand wired circuit boards at each end to terminate the ribbon. The board at the extruder has mostly header pins for the motor, thermistor, hot-end fan, etc., and one screw terminal block for the hot-end heater. The other end has a double row header for the ribbon to plug in and screw terminals for all the wires that connect to it.
Since I used an existing cable and did not have the necessary tools to terminate the ribbon any other way, I left the cable in its original length which is a little too long, but hasn't caused any operational problems.
I'm designing a new printer and plan to use the other half of the flat flex cable for its extruder connections, but it got me thinking that maybe others would find such cables useful.
For a single extruder you need 4 wires for the motor, 2 for the thermistor, at least two for the hot-end heater, 2 for a hot-end fan/always on +V and ground, and maybe a few more wires for a print cooling fan, autoleveling probe, limit switches, etc. The cables I've been looking at are spec'd for 3A on each conductor, but header pins are typically rated for 2A, so for a 12V 40W hot-end heater you would need to double up the conductors in the ribbons and the header. For 24V 40W heaters a single pair of conductors should be OK. So we need a minimum of 8 conductors in a 24V system and 10 in a 12V system, without any extras. 16 conductors would allow a lot of options without increasing mass or bulk too much.
I did some digging and found a few different manufacturers who sell FFC in bulk, on 50 m spools. I am looking into the necessary tooling to attach connectors and thinking of offering a made to length, 16 conductor cable consisting of two 8 conductor ribbons with dual row header sockets at each end, along with a set of matching termination boards, one for the extruder carriage and one for the printer's frame. The boards would have header pins for the FFC and quick connect terminals similar to these:
or screw terminal blocks and/or header pins and/or solder pads/holes for wire leads, as well as screw holes for mounting.
Here's a couple pictures of the ribbon and termination boards in my printer. Of course what I would offer would look a little better because it would be properly designed and fabricated at a PCB shop.
Is there any interest in this sort of thing?
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
I eventually settled on a cable I found in a junk pile at the makerspace. It is a flat flex cable from a tape library robot. The original cable had two ribbons with 17 conductors and 34 pin double row header sockets on each end. I didn't need so many conductors, so I carefully split both the cables and connectors length-wise and ended up with two 16 conductor cables. I have been using one on my printer for 2+ years and it has performed perfectly. I added small, hand wired circuit boards at each end to terminate the ribbon. The board at the extruder has mostly header pins for the motor, thermistor, hot-end fan, etc., and one screw terminal block for the hot-end heater. The other end has a double row header for the ribbon to plug in and screw terminals for all the wires that connect to it.
Since I used an existing cable and did not have the necessary tools to terminate the ribbon any other way, I left the cable in its original length which is a little too long, but hasn't caused any operational problems.
I'm designing a new printer and plan to use the other half of the flat flex cable for its extruder connections, but it got me thinking that maybe others would find such cables useful.
For a single extruder you need 4 wires for the motor, 2 for the thermistor, at least two for the hot-end heater, 2 for a hot-end fan/always on +V and ground, and maybe a few more wires for a print cooling fan, autoleveling probe, limit switches, etc. The cables I've been looking at are spec'd for 3A on each conductor, but header pins are typically rated for 2A, so for a 12V 40W hot-end heater you would need to double up the conductors in the ribbons and the header. For 24V 40W heaters a single pair of conductors should be OK. So we need a minimum of 8 conductors in a 24V system and 10 in a 12V system, without any extras. 16 conductors would allow a lot of options without increasing mass or bulk too much.
I did some digging and found a few different manufacturers who sell FFC in bulk, on 50 m spools. I am looking into the necessary tooling to attach connectors and thinking of offering a made to length, 16 conductor cable consisting of two 8 conductor ribbons with dual row header sockets at each end, along with a set of matching termination boards, one for the extruder carriage and one for the printer's frame. The boards would have header pins for the FFC and quick connect terminals similar to these:
or screw terminal blocks and/or header pins and/or solder pads/holes for wire leads, as well as screw holes for mounting.
Here's a couple pictures of the ribbon and termination boards in my printer. Of course what I would offer would look a little better because it would be properly designed and fabricated at a PCB shop.
Is there any interest in this sort of thing?
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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