CNC lathe conversion: start, stop, Fwd, Rev
- Thread starter slow-poke
- Start date
If you attach a pendant to your CNC system you can usually program the buttons to do specific M and G Codes. For my mill, once I set the speed with an S1000 for example the two buttons, "Spindle" and "Stop" do the start and stop where Start is M3 and Stop is M5. One could program another button to do the M4 for reverse.
In the case of LinuxCNC (and MACH3/4 is likely the same) you can assign physical inputs in the HAL and INI files to connect inputs to the original switches. I expect all those small one card CNC systems can do the same thing.
In the case of LinuxCNC (and MACH3/4 is likely the same) you can assign physical inputs in the HAL and INI files to connect inputs to the original switches. I expect all those small one card CNC systems can do the same thing.
While a VFD is not CNC, I think the principles are the same. The various switches and levers feed the control system and the control system operates the lathes spindle motor according to the control system programming.
If your manual controls are truly manual, you would have to make switches and activation systems.
If your manual controls are truly manual, you would have to make switches and activation systems.
Perhaps a screen shot will make sense here too. Notice the buttons by "Spindle:"
Clockwise click on the Right Button. "Stop" button changes to an active "Stop". Then click on the '+' button to increase speed. The '-' button to decrease speed. Want to turn it in the other direction click the left button. You then have to press the '+' button to bring it back up to speed.
You can also create custom panels like the one on the far right. That shows the spindle speed as reported by the encoder and the bar changes from red to green when the target speed has been reached. I also added buttons to quickly move to XY 0 and Z 0.
Clockwise click on the Right Button. "Stop" button changes to an active "Stop". Then click on the '+' button to increase speed. The '-' button to decrease speed. Want to turn it in the other direction click the left button. You then have to press the '+' button to bring it back up to speed.
You can also create custom panels like the one on the far right. That shows the spindle speed as reported by the encoder and the bar changes from red to green when the target speed has been reached. I also added buttons to quickly move to XY 0 and Z 0.
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.
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.
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 biggest issue with constant SFM with facing is you have to know where the cutter is relative to the lathe centerline. For CNC Lathe systems with automatic tool changers it's not such a big deal to install a tool and just like on a mill have a new X axis position. But manual users who like the features of an ELS but don't like CNC will at the drop of a hat grab a wrench and loosen, then twist, and then tighten the QC Tool holder. Now the tool tip is at a new X location.
For facing you can just move away from the headstock, probe in and reset the zero. But turning it's harder. Now it's touch off the work. Measure it. Enter it as diameter or divide by two and enter in radius. My ELS has the SFM mode so as long as the X is correct you can see SFM instead of RPM and tweak the VFD as you face the work. But nothing is automated.
As you can see, it gets convoluted really quickly.