So the Shapeoko2 arrives with loose wires on the stepper motors, and from the learnings from building a 3D printer, noise can make a big difference to the final product and performance of the stepper motors. So twisted stepper motor wires are called for!!
- create a twisting jig for the cordless screwdriver.
- twist one pair of coil wires clockwise. In this case the Green & Black cables. Then the second pair clockwise also. (Blue & Red)
- then twist the two pairs together ANTI clockwise. So it all works together stopping any unwinding
Merry Christmas !!
I like the twist jig. Did the kit not come with shielded wire?
Hi
No just 4 loose cables. I also bought steppers for the 3D printer I am making and they all came loose.
Noise was an issue I spent some time overcoming with my electronics. I am not sure if I tried twisting my motor leads, or not. My solution was much different than that though. I settled on optically isolating my step, and direction, control lines. That cleared everything up for me.
Before I did that noise was coming out of my drives, and propagating into all of my other control electronics, wreaking havoc on system operation. Stopping that noise from entering my system at the source, the drives themselves, fixed everything for me.
The motor side of things is not really sensitive to noise. Although it is where the noise comes from. That noise is going to be in the drive board before it even gets to the motor leads too. You can’t really twist your drive board up either to eliminate it.
Physically isolating my control signals did the trick for me though. Noise could not jump the optocouplers. Plus optocouplers need quite a bit of current by themselves to trigger on. So they add immunity by way of hysteresis by themselves. A little spike is not going to phase an optocoupler. It will phase logic electronics though. Sensitivity between the devices is orders of maginitude different. Sometimes a dull knife is the solution.
At least it was for me! I have noticed a lot (all?) of higher end stepper drives have optically isolated control lines too. So it isn’t like I invented anything here, I just rediscovered it for myself.
Here’s a snippet of one of my motor drive schematics with the optical isolation circuit in it. http://i.imgur.com/wmbrCVI.png There really is not quite enough of the circuit to clearly understand it. The optocoupler is triggered on a low input line, the anode is held high. This causes a high output on a low input. Then the output of the optocoupler goes through a Schmitt inverter to square it back up, and invert it again. Optocouplers naturally have slouching signal shoulders. So for a crisp waveform a Schmitt trigger is essential.
Anyhow, this comment is turning into a book so I’ll end it here with an oscilogram of the corrupted step signal before it was optically isolated
http://i.imgur.com/JVyX6n5.jpg For the after signal just imagine a clean square wave.
Great thanks for the info
I had major noise issues with one of my first builds. The problem wasn’t with missed steps, but rather my limit switches were triggering. I did anything I could think of, grounding everything, using shielded wire etc etc. The solution turned out to be simple, use NC (Normally Closed) switches.
True the noise did not go away, it just became a non-issue
OK Mr. Pessimist, I’ll put this simply. If I ask the software to mill a square 1.000" and it mills it 0.9998" in wood I’m happy. Thats a period, Its wood. Movement from humidity will cause more change than noise, and species combined … Its not an argument, but a point of where you are happy with it.
@Eric_De_Larwelle OK. I’m sorry I bothered trying to explain anything to you. Good luck!
No Paul, Don’t be sorry for explaining. But understand this. If it works for Us … Its not broken. More …
@Eric_De_Larwelle Right now I am reminded of Galileo’s response to the Inquisition, And yet it moves. I will leave it to you to fathom why.
