My favorite part, considering I'm an electrician.
Before I ordered any parts, I started researching how I would actually control the CNC part of the table. I knew that Windows-based software tends to be pretty expensive (for me, anything more than free is expensive) but it certainly does everything you want it to do, and easily.
I found an interesting piece of software called EMC that runs on Linux, and since I have tons of experience with Linux, this was the best way to go. I had a spare computer so I formatted and installed Ubuntu, then installed EMC. I also found a free 2D CAD program, QCad, and a free CAM program, GCam, and a bunch of other assorted program that I went ahead and installed just in case.
Did I mention they were all free?
Back to the hardware. I went to the EMC site and found a list of assorted hardware that was known to work with EMC, so that's what I picked. It was probably a bit more expensive that the cheap off-the-shelf combination of hardware, but I wanted something that I knew would give me the least problems.
I settled on a controller board and 80V power supply from PMDX, four G201 drives from Gecko Drive, and stepper motors from Keling Inc.
Since I love motor controls, I designed and built the control circuit that would take care of relays, power, limit switches, and the e-stop circuit. A little bit of on-the-fly rewiring and everything worked as planned.
Since I am posting lots of pictures now that may or may not follow along with the attached post, I am going to start giving a brief explanation of what each picture is.
The first picture shows the connector I mounted on the plasma cutter to remotely control the torch. All it consists of are two jumpers between the torch trigger contact and eventually back to a relay on the controller board.
The second picture shows my controller board mounted on the four Gecko drives, and all those are mounted on an aluminum heat sink rail.
The third picture is the 80V power supply from PMDX.
The fourth picture is the front of the controller. Kind of obvious what everything does here...
The fifth picture shows the internals of the control enclosure. the large gray cables across the top are motor cables, the obvious controller board and power supply, the power and e-stop relays, the terminal block and massive toroidal transformer. I added a connector for the parallel cable, and let me tell you, #28 wires suck! The three black cables in the bottom right are controller power (120V), torch remote control, and the switched receptacle for the duct fan.
The sixth picture is the motor disable switch and the manual torch override buttons. The motor disable just tells the controller board to shut the current off to the motors so they can be jogged by hand. The torch override is so I can turn the torch on and off by hand. One button is momentary, the other push-on-push-off.
The interesting thing about the torch override is the way Miller makes their plasma cutters. When you squeeze and hold the trigger, the torch and air turn on for cutting. When you release the trigger, the torch turns off but the air stays on, I assume for cool down or whatever. The air will not turn off until the trigger is jogged, so I added a button to manually jog the air. Eventuall I will get the software to do this. |