1
\$\begingroup\$

The main scope of this question is about hobby 3D printer. The element in scope are

  1. 10K NTC thermistor for temperature sensor
  2. Stepper motor NEMA17 required about 1.0 A
  3. Hotend heater 12V 40W required about 4.0 A
  4. heated bed 12V 120W equired about 10.0 A THis is flat cable that I refer to

enter image description here

The specification says 28 AWG which allow 1.5A current The socket connector allow 1.0A max Can I just multiply wire to suit current requirement? Are they any pros. and cons. to consider? Note. I just need solution for better wire management you can suggest better option for this problem.

\$\endgroup\$
8
  • 1
    \$\begingroup\$ You can't find more suitable multiconductor cable? \$\endgroup\$
    – DKNguyen
    Commented Dec 17, 2021 at 2:05
  • \$\begingroup\$ @DKNguyen I think it would be nice if cable can bend easily when machine head moving. \$\endgroup\$
    – M lab
    Commented Dec 17, 2021 at 2:10
  • 1
    \$\begingroup\$ the cable in the picture is not suitable for repeated flexing ... the insulation tends to become stiff with age in hot environment \$\endgroup\$
    – jsotola
    Commented Dec 17, 2021 at 2:31
  • 1
    \$\begingroup\$ Are you sure about 1.5A? That's higher than the awg chart for copper wire in a chassis wiring, and those cables are unlikely to be copper. \$\endgroup\$
    – Passerby
    Commented Dec 17, 2021 at 2:31
  • 2
    \$\begingroup\$ Have you seen commercial printers use this cable? If not, that suggests it is probably not a good idea However, in the interests of experimentation, give it a try. Yes, you can parallel conductors, but even doing this I’d be thinking 10A might be stretching the limits. If it works for you, sweet, if not it will be some hard won experience for you. \$\endgroup\$
    – Kartman
    Commented Dec 17, 2021 at 3:14

3 Answers 3

Reset to default
2
\$\begingroup\$
  • OK > 10K NTC thermistor for temperature sensor
  • OK > Stepper motor NEMA17 required about 1 A
  • not OK , unless twinned pairs > 4 A Hotend heater 12V 40 W avg
  • not OK > heated bed 12 V x 10 A =120 W

The problem is not the wire but the very small contact knife surface of the insulation displacement contacts, (IDC) for current rating.

1 to 1.5 A is the typical limit for do not exceed.

The motor is quite noisy and the thermistor will need to be filtered with a metal film cap for RF as well as a guard ground wire to reduce crosstalk.

I found this reference afterwards. http://www.mosaic-industries.com/embedded-systems/electronic-instrument-design-new-product-development/cables/ribbon-cable-current-rating

\$\endgroup\$
2
  • \$\begingroup\$ What about physical property due to repeatly bending? \$\endgroup\$
    – M lab
    Commented Dec 17, 2021 at 20:11
  • \$\begingroup\$ You never repeatedly bend wire radially, rather have a curl and move along the axis of the curl to simply change the large radius. Otherwise it breaks \$\endgroup\$
    – D.A.S.
    Commented Dec 18, 2021 at 10:42
2
\$\begingroup\$

Silicone wire is relatively cheap and available in any gauge, as well as in 2 conductor cables. In addition to great flexibility and thermal resistance these wires tend to have more and thinner strands than PVC-jacketed wires of same gauge.

Get correct gauge pair for each device, bundle them all into braided cable sleeve. Use soft nylon or polyester braid for most flexible solution, good for moving frames and platforms. Alternatively use PET braid to provide abrasion resistant semi-rigid support for wide movement range, like printing heads.

Don't use IDC or solder tab connectors. Use crimping contacts with careful crimp over insulation. Alternatively you can use solder connections on one side of the wire (e.g. to motors) but make sure you affix wire bundle with zip tie at some distance from solder connection, because soldering may create locally brittle spot. Zip tie will prevent both braid fraying and wire bending at solder joint.

This may look like overly expensive and complicated, but it will ensure trouble free wire management solution for many years. At my work many 3D printers are used 24/7 and sooner or later every piece of ribbon cable under flex has to be replaced. Only FFC cables last as long as silicone (in fact, probably longer), but they are not suitable for very high currents. You can use them for sensors and steppers though.

\$\endgroup\$
2
  • \$\begingroup\$ This doesn't actually address the question properly. Could you expand on why ribbon cable isn't good for this? \$\endgroup\$
    – Passerby
    Commented Dec 17, 2021 at 20:06
  • \$\begingroup\$ @Passerby "you can suggest better option for this problem" is the part of the question I was trying to address. And I think "sooner or later every piece of ribbon cable under flex has to be replaced" somewhat answers the "why" question, at least from practical experience point. The full answer probably needs to go into the aging properties of different insulation materials, as well as mechanical analysis of flexing capacity of say 7/26 vs 65/36 stranded wires. I do not claim to have any scientific knowledge in either area. You are welcome to downvote, of course, if the answer has no merit \$\endgroup\$
    – Maple
    Commented Dec 17, 2021 at 20:48
1
\$\begingroup\$

The type of cable you are looking for is called "continuous flex". Depending on gauge, it's about $0.50/foot from a place like McMaster which is high compared to normal stuff but you'll only need a few feet so it shouldn't be a deal breaker.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.