Printable wire twister
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I designed a wire twister that's very useful for wiring printers and other machines that have long runs of wire. It uses Wago 221 lever nuts to clamp the wires so it's very quick and easy to use. The Wago lever nuts are good for 24-12 gauge wire, so they should be good for almost any wires you'll to need to twist.
The clamps hold the Wagos tightly, but it's still a good idea to put a drop of glue on them before inserting them into the clamps. You should probably glue a piece of rubber onto the fixed clamp to help keep it from slipping off the table or shelf that it's clamped to. The bolt and nuts I used are 5/16" but it should be easy to modify things for 8mm hardware.
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@mrehorstdmd
Nice design, but as a point of note, commercial "twisted" wiring is not actually twisted!
The wires are wrapped around each other without individually being rotated, so there is no residual stress.It's lot more tedious doing it that way, but the resulting cable is stress-free and has no tendency to try and unwind itself or kink up.
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@rjenkinsgb The twisted pairs I get from this work just fine and don't try to unwind. I usually twist until the wires start to kink, then stop and give them a final pull before releasing them. It's best to strip the wires before twisting them, but the Wagos don't care if you strip or not- they grip just fine, even teflon insulated wire.
It probably won't work very well for super flexible silicone insulated wire. I don't have any of that to test it.
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@mrehorstdmd the way I remember being taught to twist wires was to put a twist in each wire individually using two hand drills, both in the same direction; then clamp the ends together and let go. They twist round each other spontaneously.
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@rjenkinsgb said in Printable wire twister:
commercial "twisted" wiring is not actually twisted!
Good point. Maybe this can also be designed with some 3D contraption. In any case, always remember to cut the wires longer than you need because of the 'shrinkage'.
I don't twist wires, just individual teflon wires in the drag chains. Easier to add/remove this way.
Edit: If each of the 4 wagos could turn freely, will this eliminate most of the self twisting of the individual wires?
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@zapta said in Printable wire twister:
Edit: If each of the 4 wagos could turn freely, will this eliminate most of the self twisting of the individual wires?
Yes! That would be a really nice upgrade.
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@zapta It's generally a good idea to twist wire pairs, especially those carrying pulsed currents like motor windings, bed heaters, and nozzle heaters. The twisting reduces EM radiation and coupling into adjacent wires.
Yes, it would be nice to have the Wagos rotating as the twister spins, but it's entirely unnecessary. It works well as-is. Try it, you'll see. I've been using this method of twisting for years.
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@mrehorstdmd , I used to do it as a kid playing with antennas. It was supposed to achieve a certain impedance that the antenna and the electronics liked.
In my printer (V2.4) the main harness is along the drag chains. I opted to optimize for wire longevity by having independent parallel wires in parallel and using teflon insulation for lower the friction. Twisting pairs of wires may improve EMI but will also scarify the mechanical longevity so it's a dilemma.
My thinking is that the only 'weak' signals there are in the temperature sensors wires and those signals are slow enough such that the Duet can filter it out in hardware and/or firmware.
Anyway, this is a very nice design. Especially the use of the wagos for quick connect. You can also add to it a table with the shrinkage ratio for low, medium and high twist densities so people know how much extra wire to cut.
Out of curiosity I looked for cheap free swivel solution. The best I found so far are fishing accessories like this https://www.aliexpress.com/item/4000504841030.html . Not sure how free they swivel but would be interesting to experiment and see if it makes a different.
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@zapta I'm not so sure about the life of wires inside a drag chain. I think the key to long life is large bending radius above all else. I sometimes wonder how much time some people have to spend chasing down odd printer behavior because of wires fractured within their insulation because of the small bend radius of their drag chains.
Looking at it on a small scale, bending a twisted pair actually twists the wires instead of bending them. I've seen that idea used in earphone cables in which the wires are spiral wrapped around a fiber core. Even sharp bends in the cable turn into twists in the wires instead of bends. You can see the effect by bending a spring- as the spring bends, the wire twists. I suspect metals used in wires hold up better under repeated twisting than repeated bending.
I use twisted pairs inside the extruder carriage drag chain and have had no issues for years, but I use a very large bend radius. For my bed moving in Z, I just have a long loop of twisted cables hanging within a woven cable jacket, and again, no problems for years.
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@mrehorstdmd I'd say the is as much about cable choice as it is about bend radius. Flexible cables use many more cores but of much small diameter and the insulation is usually silicone. Thin conductors can have a much smaller bend radius than thick conductors. Typical 12 awg flexible might have something like 680 very fine strands.
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@mrehorstdmd said in Printable wire twister:
I'm not so sure about the life of wires inside a drag chain. I think the key to long life is large bending radius above all else.
I think it's based on some ratio between the radius of the drag chain and the radius of the cable itself. The thicker the cable, the more the stress on its outer side for the same bending radius. Twisting two cables in a sense making a thicker cable from two thin wires. I think that each of the two wires has less stress, for the same drag chain radius is it's left alone and not bound to other wires. Having a slick insolation vs more grippy silicon also helps with preventing stresses and letting each wire moving independently.
I am not an expert but this is my experience.
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