CNC conversion of lathe. I'm curious what approaches people have taken with respect to adding CNC control while maintaining the original manual start, stop, fwd and reverse switches?
Yes. Project #42 for my ELS was to connect the RS232 port on the ELS to the ModBus port on the VFD and control the spindle that way. The infrastructure is there now even including ALT buttons on the numeric keypad for spindle control.The other approach is of course to only automate the axis and leave the manual start stop speed alone. To use you turn the spindle on manually then activate the cnc program. When the program is done turn off the spindle. I’m doing this on my ELS conversion to start. Later it is possible to add start/stop and speed to the control by using a vfd interfaced to the control. At least the rocketronics ELS does this. I saw at John Danmyers he has spindle control too on his equipment with his ELS solution.
On reason to add spindle speed control to your control is then the control can achieve constant radial velocity under the cutter by speeding up the spindle as the cutter traverses the part. I’m thinking about lathes here.