From a discussion about CAN Connectors, @Tom_Line sketched up a fixture to help twist wire pairs (Can Connectors - #30 by Tom_Line) without twisting the individual conductors (which is how commercial wire twisting machines work). I tried to make as minimal a test implementation (I mostly used wood and a dowel rod) but couldn’t get as much consistency in the wire twisting - I attributed to the fact that the wire could still twist before it caused the bearings to rotate which made the bearing movement inconsistent.
Like the Grinch, I puzzled my puzzler until it was sore and kept going back to the videos of commercial wire twisting machines. I wanted to come up with a contraption that would make sure the wire was not an active participant in staying untwisted but was just along for the ride.
To share my inspiration, this is the machine watched over and over:
So what happened?
This:
Which became this:
To use it, you load the wire on the spools and feed the free end through a hole in the center of the gears holding the wire spools - clamp the other end in a vise. With one hand you hold the center handle and either turn the hand crank or drive it with a drill. The rate of the turning and the speed that you move away from the fixed end of the wire determines the twist rate.
The tool keeps the wire spools in the same orientation through the entire rotational cycle so the conductors never twist but just braid themselves around the other.
How’d it work? Great! i thought the crank handle would make it easier to handle than using a drill but in practice it’s pretty slow; to get 4 turns per inch, you need to move back very slowly so the drill is much more practical to use. How fast can you spin it? I’ve had it up to about thousand RPM and everything held together; to be honest, you’ll never twist that fast and I sort of got scared to go much faster. It seems none the worse for the wear.
All in all, this turned out really great. It was a good design and was done almost entirely in the virtual space without a million test prints.
If you want to check it out for yourself, the OnShape document is at Onshape. You can check out the final assembly at the top level of the document and grab the lower frame (where the gears are) and take it for a twist.
Check out the comments for some additional notes on the design, printing and assembly tips, and some general usage notes.
Feedback welcome.
It was a fun project - enjoy!
– Chris Herzog
. Crazy how similar our thinking was.