I do have a tachometer from Reed. At 500 RPM I get 410 RPM consistently, so at least that is "reliable". Between 500 and 1000... pretty much nothing happens, it always spins at 410.
If anyone has replaced the controller with something more reliable, please let me know.
If you guys were to replace the controller board. Which controller board would you choose to get the most control out of the spindle?
I don't have a Novakon, but I do use Mach to control the spindle on my home made lathe and mill.
I use Homann Designs speed control board. Tiny little thing. Deceptively small. Works big.
I used the DC-06 model.
Both my machines use a DCmotor. I use the motor speed controllers from Surplus Center.
I am running my mill on 220 VAC and 110 on the lathe. I set up using the top speed I want to use, which is 6600 on the mill. Then I selected my slowest speed possible to actually mill something. I was able to dial in near exact for those two speeds. In between though was off a bit more, but still in range. Not good enough for rigid tapping, but well within parameters for milling.
Dont forget to set the pulley speeds, Under config pulley you set the min and max speed for each pulley. Mach uses that. Even if you use only 1 pulley you must set pulley #1 to the right values.
Just out of curiosity, is the controller on this mill made by Sangmutan (it would have a rip-off Harley Davidson logo slapped all over it)? If so there are a couple things outlined in this thread (New!2200W 3000~10000RPM BLDC Motor Controller) that might help you out. In particular, note how to drive the board with a standard 0-5V input signal, so you could use an output from a parallel port, or just a power supply, to test to see if it's the signal that's screwing up the speed. It seems that those in that thread did get consistent speeds.
If you still have troubles posting over there, or PMing or emailing "Kung Fu Panda" may get you an answer. He seems pretty helpful and knowledgeable (note the photo & instructions on p5 of the thread for connecting to 120V).I did manage to complete the spindle calibration and I am within 50rpm across the board with the speeds I have randomly tested. I can live with that and I can reverse the spindle with the m4/m3 commands so that is good.