[Johnsinski]

Just getting around to building my CNC. I have been playing with the X-axis and found some odd behavior.

One problem was starting the axis movement after sitting more than 10 seconds, even thought J4 was on (current reduction disabled).

Second problem was erratic stepper motion at very slow speeds, like .1 mm/s or lower. I think this is due to the "sync" modes changing.

I'm hoping to do this mod and fix the problem. If I don't want the computer to control it (pin 1) where could I connect the wire to on the board (or a manual switch)?

Otherwise the x-axis is working very good at normal and high speeds.

Thanks for the tip.

[Fastest1]

Try a longer pulse.

[Johnsinski]

This mod seems to have fixed my erratic stepper behavior at super slow speeds and startups. Also LinuxCNC does have options to control pin 1 so that works from software too.

This was bugging me, thanks for the thread.

[samc99us]

Johnsinski,

Can you give me the detailed steps on controlling pin 1 from LinuxCNC? I'm pretty tempted to bypass the software and just go to ground from the 10K resistor instead of Pin1 to disable the idle current issues. I'm definitely still loosing tiny steps during the first 10 seconds of milling.

Thanks,
Sam

[Johnsinski]

I don't have the machine in front of me, I'll get a picture later today. But you can set the pin1 high or low from the machine setup program (stepconfig?) I think it's on the page with all the step and direction pinouts. It might be possible to control from inside the gcode as well, haven't had a need to do that. Not losing any steps, no delays, runs very slow to very fast, like 400 IPM fast! Not reliably, I have it set to a max of about 100 IPM, totally reliable.

- Edit --

It's on the parallel port setup page. I soldered mine to the pin 1 on the Hobby Pro. Then set the very first pin, pin1 to digital out 1, and check the invert box. That seemed to work for me.

[samc99us]

All,

This mod saved my HobbyCNC Pro Driver Board from imminent departure by way of the local landfill. I was completely tired of lost steps and funny hissing noises from two completely separate sets of NEMA23 motors.

Thanks John!

I set mine up the following way:

Set "Amplifier Enable" to Pin1 in the StepConfig of LinuxCNC. This enables idle current reduction when the machine is in stop mode (orange power button depressed in LinuxCNC) and disables idle current reduction when the machine is commanded active from LinuxCNC. Works like a charm.

[BjornskiNL]

I just read this tread and as I am in the stage of building my own cnc with the hobbyCncPro board I am verry happy to receive this information. My words of thank you from the other side of the world