by Ed Nisley
The wires coming out of Sherline CNC milling machine stepper motors, as with most small stepper motors, emerge from an epoxy-filled opening. As a result, whenever the motor or wires move, all the stress concentrates right at that epoxy surface.
Which is exactly where the wires will break…
There’s no good way to add strain relief to that point (more adhesive isn’t helpful), but you can anchor the cable to the motor frame so the individual wires do not move relative to the motor.
Cable ties will suffice. Add one around the entire motor to hold the wires in place, then lash the spiral sheath to one of the unused mounting holes in the motor frame.
Pull those ties until they squeak! You can grab the tabs with flush-cutting diagonal cutters to get some traction, then rotate the cutters against the ratchet housing to pull another notch past the ratchet. When it’s so tight you’re stretching the tie, then it’s tight enough; clip the end off with the cutters.
To cross-check, wiggle the connector end of the cable. If the wires move at the epoxy, you haven’t done a sufficiently good job. Repeat until satisfied.
This works for the milling machine and, as shown in the picture, the rotary table. Just do it!
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