Where zero is, and how depth is measured#

Zero is a promise#

Every number in your G-code is measured from work zero (X0 Y0 Z0). The app picks a spot on the stock; you must zero the machine at the same spot. If they differ, every cut moves by the difference.

X0 Y0#

Usually the bottom-left corner of the stock, because it's easy to jog to and find by touch. Pick the centre if you locate work from the middle, as with a fixture.

Z0: top or bottom?#

  Top of stock (usual)          Bottom of stock

  Z0 ──────────────  top        Z+12 ────────────  top
       │  stock  │                   │  stock  │
  Z-12 ──────────────  table    Z0 ──────────────  table

• Top of stock: touch the bit on the material. Cuts go negative. Easy, and what most people use.
• Bottom of stock: touch on the table. Useful when the board's thickness varies but the finished height from the table must not, such as flattening a slab.

Mix them up and the cutter plunges a whole stock thickness too deep. That's why the export review repeats your choice.

Depth is from the start#

Depth is how much this cut removes, measured down from where it starts. It is not a Z position.

  Z 0  ───────────────── stock top
  Z-3  ─────┐     ┌───── pocket floor  ← engraving starts here
            │     │
  Z-4       └─────┘      engraving (Depth = 1)

Start = pocket floor (−3), Depth = 1 → ends at −4. Type 4 by mistake and you'd end at −7.

The form shows the resolved start Z beside the Start label so you can check.

Why Auto start is cautious#

Auto looks at what earlier cuts removed and starts at the highest material left. If any part of the new cut is over uncut stock, it starts at the top.

Starting too high wastes a little air. Starting too low crashes the bit. So it picks high.

Why cut through at 12.5 mm on 12 mm stock?#

Stock thickness varies, and the spoilboard is never perfectly flat. An extra half millimetre makes sure the part separates.

How-to: Set your work origin · Cut into the floor of a pocket