So I have laser cutter. And I am thinking about buying a control unit (this one, to be exact).

But my concern here is the following: If the input DXF file contains splines, they will be converted to lines (G01) and arcs (G02 or G03), since these are all the entities G-Code has.

Since have absolutely no knowledge about motors or controlling them, the question is as follows:

  • Does the control unit from the link do the same? Does it convert DXF to G-Code?
  • If yes, is there a control unit that would quide my laser cutter over a spline from the DXF and NOT on some series of lines and arcs?
  • This webpage says that only Z axis is controlled with PID. Why? How are other axis controlled. Does this mean I could in general choose between PID and G-Code?
  • 1
    $\begingroup$ When a printer prints splines it converts them to linear segments first, just lots of them. Similar deal here. Its possible for a controller to follow a spline, however, the controller is still bound by dyamics so how well it follows the spline is a questionmark, and whether any specification would be better with this control architecture. No G code is not what drives the motor a controller does. $\endgroup$
    – joojaa
    Commented Feb 20, 2018 at 20:33

1 Answer 1


Not really an answer, but I can't comment, so:

Does this mean I could in general choose between PID and G-Code?

PID and G-code are not two interchangable approaches to control a CNC-machine, they serve different purposes.

G-code is basically the programming language to tell the CNC-machine where to drive with the axes, when to do stuff like turn on the laser, turn on cooling water, turn on process gas, whatever your machine can do.

PID is a (simple) closed-loop control algorithm, in case of the control unit you linked, it ensures that the z-axis is at the position it is supposed to be, even under the influence of some disturbance.


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