I have a G0704 cnc that I built about 8 years ago. It uses mach3, an ethernet smooth stepper and a C11g breakout board.
For the spindle I'm using a 1.5hp bldc motor and a GlockCNC 1200 watt 1200WBD driver. The speed is controlled via the C11g breakout boards onboard 0-10v Analog converter, connected to the 1200WBDs Analog input terminals. The breakout board converts PWM into a 0-10v Analog signal.
My spindle works well enough, but either the Analog converters output isn't very linear, or the 1200WBD driver doesn't convert the voltage to RPM in a linear manner.
I can easily tune the spindle speed to match the mach3 commanded speed using the C11g onboard potentiometer,. But it only ever matches @ that specific speed. For example, if I enter 4000rpm into mach3, and adjust the potentiometer untill I have 4000 RPM at the spindle, entering 3000rpm in mach3 will get me about 2700rpm at the spindle. The closer I get to 4000, the better they match. Above 4000, they will start to diverge again. This same non-linearity manifests no matter which RPM I use as the base for tuning.
My 1200WBD can also accept a 5v 1khz-2khz PWM signal to control the speed via PWM duty cycle.
My question is:. If bypass the 0-10v converter, and feed the PWM signal directly to the 1200BWD driver and use PWM duty cycle to control the speed, would I get better linearity?
It's not difficult to bump the commanded RPM up/down untill the tachometer is where I want,. But it would be nice if I didn't have to do that.