[LeeWay]

Hey guys. Before I zapped my Xylotex board the other night, I was able to jog the three new motors that I have. 270 oz. 2.8 amp bipolar. Both directions, all three axes. I was running Turbo cnc at the time. I wasn't using shielded cable. Just 3' single stranded wire to each motor wire needed for testing purposes.
My question is this. On the x axis while jogging, the motor made a thimping sound in both directions. Sounded kinda rough. It didn't surprise me then that this happened with the y axis. Same thing. Thinping. But then on the z axis, the motor ran smoothly in both directions. All three wired the same. All three vrefs set the same.
Any ideas as to what might be the cause and which operation would be the unusual one?
Thanks in advance.
Remedies, fixes and settings are especially welcome.

[H500]

I believe the xylotex can only handle about 2.5 amps. At 2.8A, they might overheat and shut down intermittently. Try reducing the current, or add a fan.

My driver is based on the same chip as xylotex and the motors run very smoothly when set to 8 microsteps. Check your board to make sure its not set to the full step mode, which would be much rougher.

[LeeWay]

Thanks H.
I didn't have the board set at the max for the motors, but very near the max of the Xylotex. 3.5 volts per axis which given the chart in the instructions, equaled to about 2.5 amps. The settings on the board with the jumpers were as shipped. All thee the same. I am wondering if one motor may be bad, but I will need to check further after I get my other board in.

[ger21]

Like H500 said, try reducing the current. Jeff at Xylotex has said that thew closer you get to the rated current, the less smoothing you'll get from microstepping. He usually recommends running a bit less than the rated current. Try around 2 amps and work you're way up and see if it makes a difference.

[LeeWay]

Thanks Gerry.
I will do that. I think that accuracy is much more important to me anyway.
The parts that I was cutting out by hand was taking a long time to do. Mainly setups for jigs and such. At least if the rig I'm making will cut out these parts on its own, it will free me up a little to do another step at the same time. That is really what I am looking for. Better accuracy is also a plus.

I take it that the thumping noise I heard is common then, according to different settings? Not a bad motor or two.

[ger21]

Lee, microstepping doesn't necessarily imrove accuracy. Actually, accuracy is not the correct term. I think you meant precision. The main benefit of microstepping is smoother running. The reason you don't always get better resolution, is that when microstepping, each microstep only gets a small amount of torque. with each successive microstep, the torque is a little more. The torque from a single microstep may not be enough to move your machine, so it may take a few microsteps for the torque to build up to actually move to the correct position. When designing a stepper system, it's probably a good idea to design for the full step resolution, and just count on the microstepping for smoother running.