[gnea/grbl-Mega Issue#101] Spindle Speed

I set up the firmware and started playing around with the controller.

Motion seems fine but the spindle speed seems to be binary on/off rather than continuous.

I can’t seem to be able to control the speed at all.

Either the spindle is off using the slider and then after moving the software slider more than halfway then it suddenly turns on full speed. I have a Dewalt router spindle and I’m using a SSR with a 10A fuse.

Any suggestions?

Thanks!