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« on: January 08, 2019, 12:34:05 PM »
I've been wanting to start using a smoothstepper so that I can run windows 7 64 bit on my CNC machine but have some concerns about the features I may be losing if I make the switch from parallel port to Smoothstepper.
First, i'm limited to the USB version. My CNC hardware and PC hardware, all breakout boards, pc motherboards, stepper drivers, power supplies etc are all mounted in the same mining-rig enclosure, which is mounted to the side of the CNC enclosure. The breakout board connects to the PC motherboard via headers, and the smoothstepper would also be mounted inside the enclosure and necessarily connect to the motherboards onboard USB3.0 header. The pc motherboard doesn't have an Ethernet header, only the plug on the rear I/O panel.
I'm OCD about wiring neatness, having an Ethernet smoothstepper would mean a hole drilled into the enclosure, and a wire hanging out of the hole so it could be plugged into the back of the motherboard. Such a thing would be like having a penis growing out of my forehead. It's mere existence would be intolerable, like a snake loose in the house, I couldn't stop thinking about it until it was gone.
My biggest concern is the features I might lose switching to the smoothstepper.
First, closed loop PID control of the spindle motor. I've read online that USS smoothstepper in Mach3 can't do closed loop PID, or somehow, eliminates Mach3s ability to control the spindle closed loop. Currently, my 1.1kw bldc motor, in combonation with Mach3 in closed loop PID operation holds + or - 10 rpm, even when entering and exiting cuts. I really don't want to lose this.
Also, i've read that I will lose backlash compensation. This isn't as big of a deal as my ballscrews have almost no backlash but I do occasionally, rightly or wrongly, use it to hit a tolerance when it's is a couple thousandths undersize or oversize.
The ability to use speed override in the positive direction. I've read that the smoothstepper won't allow feed override to increase the feed speed.
Also, I keep reading about weird reliability issues, such as losing communication between mach3 and the smoothstepper, the smoothstepper running out of data, etc.
Are my concerns realistic? Is there a way to actually control the spindle closed loop, use the feed override and backlash compensation with the smoothstepper?
How does it cause these issues? does the smoothstepper override, ignore or otherwise not communicate some of the Mach 3 to breakout board communications? For example, if Mach 3 is sensing rpm via the index signal, and modulating the pwm pulsewidth to adjust RPM, does the smoothstepper not communicate these instructions to the breakout board, or does the smoothstepper somehow prevent these calculations from taking place at all?
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