I just bought a 20 year old table that was electronically fried. The plan is to replace everything inc. the motors with current tech. I want to add a plate marker and rotary axis. My experience is very limited at best. If I am understanding correctly sheet cam will work as my controller through my computer,
Hello John, welcome to sheetcam.
Sheetcam is NOT a CNC controller, rather it produces gcode which is read by a CNC controller and represents the toolpath (aka cutter motion commands) that the controller will consume while the controller is driving the motors, cutter on/off state, and reading limit switches.
Sheetcam is Computer Aided Manufacturing (CAM) software. It takes as input a .DXF or .SVG format file which is produced by Computer Aided Design (CAD) software. OnShape is a free and good CAD program. There are many others. For plasma process, you don’t need 3D CAD such as OnShape, 2D CAD such as InkScape will do. I like OnShape for sheetmetal models as it takes into account bends, K factors, and ‘unfolding’ of the 3D model into a flat sheet for cutting. I also use LightBurn as 2D CAD mainly for arts/crafty projects, it may be the easiest to use of any 2D CAD that I’ve tried.
CNC controllers are technically hardware devices, that is the electronics necessary to drive motors, relays, and monitor limit switches. Some controllers have microprocessors/ mirco-controllers (MCU) builtin to interpret gcode, thus they have firmware running on the MCU (grbl, grblHAL, and proprietary units like Langmuir FireControl). Some controllers have an MCU simply to control the motor and switch I/O but not interpret gcode, rather they use a connected computer which runs software to interpret gcode (LinuxCNC, Mach3/4, WinCNC). But even in the case of MCU which interpret gcode (grbl, etc), a connected computer is necessary to stream the gcode to the controller (such as OpenBuilds Sender, UGS, or IOSender).
Whatever you choose as a controller for your ‘phoenix’ CNC rebuild, choose wisely and take into account EMI shielding in all that you do. Hypertherm wrote one of many books on EMI effects and precautions. Read about it and take precautions against it, it will plague you if you don’t, especially with plasma CNC.
Given that I want to run a rotary in the future. Is it your opinion that I should be running Mach 3 and sheet cam over a stand alone controller available on Amazon? Thx for the explanation. I’ll be looking up the literature you mentioned.
Mach 3/4 is a fine controller I suspect, I don’t know it well, only through sheetcam post processor support and few times I’ve had to reference their doc. A lot of folks use it, flatsheet and rotary.
I use grbl v1.1i 4 axis running on a atMega2560 chip w bare minimum break out board (BOB), with an autonomous Proma SD THC. However, I have added a DIY Anti-Dive Circuit to better interface this THC to my grbl controller. I only use these grbl and THC parts because that is what my MillRight CNC came with. If I were going this route again, I’d certainly get/build a controller where the THC is fully integrated, meaning the controller is always aware of the Z axis position since the controller will always manage its motion. I like to tinker with electronics, so I’d likely use the grblHAL BOB that I referenced earlier, I actually have one that was purchased before I solved all EMI and THC issues I had with my basic grbl board. I never needed to install gblHAL / switch over to it, I use it for desktop bench testing. I would use the Proma 150 THC with grblHAL, it is not autonomous like it’s sister SD unit, rather the 150 integrates well with grblHAL and the BOB. The grblHAL BOB I referenced has mutilple EMI mitigations designed into it, such as opto-isolated I/O and default normally closed input/limit switch circuit design rather than normally open signal expectations, this is an example of EMI mitigation.
As for the computer gcode sender for grbl, I use UGS. grblHAL recommends IOSender, but UGS will also work. Some people prefer OpenBuilds Sender, I don’t care for it.
My second choice would be LinuxCNC, albeit I’m not that proficient with linux, but the greater expanse of gcode dialect and program flow control seems like it could be advantageous to have at times.
Of course I use Sheetcam for all CAM except laser. My CNC is Tri-CAM 4 axis, XYZA, meaning it can cut or etch with milling, laser, and plasma process, flatsheet and rotary.
A second vote for Linuxcnc as it does support a plate marker and the rotary axis Sheetcam has a post processor for it, Plate marker can be built from a Chicago Pneumatics air engraver and an air ram to lower the engraver.
