Milling know-how

Workpiece origin: where XY and Z really belong

The origin is the agreement between your G-code and your machine: "all coordinates count from this point." If the agreement in the CAM program and the probing on the machine are not exactly the same, the machine mills precisely in the wrong place.

Pick the origin and generate G-code: to the milling tool →

How to do it in step2gcode

  1. In the "Origin" section, choose the XY position: one of the four corners of the stock, or the center.
  2. Choose the Z reference: "Workpiece Surface" (top) or "Spoilboard" (the underside of the material, i.e. the sacrificial board).
  3. On the machine, probe exactly the same point you selected in step2gcode.
  4. Cross-check in the 3D preview: the coordinate origin must sit at the expected corner or in the center.

XY: corner or center?

In short: for sheet material use a workpiece corner (easy and repeatable to probe), for symmetrical parts and round stock use the center. The corner is the standard for sheet material: it can be probed quickly and repeatably on the machine, with a square stop if needed. Pick the corner you can reach most comfortably on your machine.

The center shines with symmetrical parts: if the stock turns out slightly larger or smaller than planned, the part still stays centered. For round stock or pre-cut blanks the center is often more practical too.

Z: surface or spoilboard?

In short: put Z on the workpiece surface when depths count from the material (pockets, engravings); put Z on the spoilboard when cutting through. Z on the workpiece surface is the easiest to probe and the right choice when pockets and engravings must reach an exact depth: all depth values refer to the surface you actually probed, and material thickness variations do not affect depths measured from the top.

Z on the spoilboard is the right choice for through-cuts: the cutter ends exactly at the sacrificial board, regardless of whether the sheet is 11.8 or 12.3 mm thick. Cut-outs separate cleanly without carving deep into the spoilboard.