Hey guys, I am in the process of converting my CNC router from a

Hey guys, I am in the process of converting my CNC router from a proprietary controller to GRBL 1.1 using Chilipeppr to control it. The original controller was in two parts, a USB board, and a parallel port stepper board. I have interfaced the stepper board with an arduino, and it works great, except I can’t get anywhere near the stepper speeds that I get when using the original board. I have calibrated the steppers and set the steps per mm (around 64). I have found that the max feed I get (i.e. $110) is 200. If I change it higher, I do not notice any increase in speed. Is this a limitation of GRBL, or am I missing something?


Do you meaning jog speed?

No, the cutting speed.

The settings are, as you say, in $110-112 for X y and z axes respectively. They will be most apparent in G0 moves.
If you’re not seeing an appreciable difference then perhaps your move length is not sufficiently long to allow the motor to accelerate the axis to top speed.

Axis acceleration is at $120-122.

I suggest you incrementally test higher acceleration and speeds until you reach what you want. You can technically go up to your motor’s stall point (for speed) but a safe margin is probably 80% of that. For acceleration the upper limit is more related to the stability of your setup and what backlash may be present on your axes.

If thinks worked ok for your proprietary controller then look up the values for those and reinput them into grbl.
I’m assuming for this purpose that you are happy that the hardware connectivity between the grbl board and the parallel driver is definitely fine (no MOSFET delay caused by low voltage signals etc).

Thanks Justin - I finally got it sorted out. I swear I was making the same changes, and it wasn’t working, but all is good now. Great job on your GRBL workspace BTW - I like the enhancements!