What should I check before pressing Go? The pre-machining checklist

In the software, before saving G-code

1. Preview every toolpath at decent simulation quality (Toolpaths > Preview Simulation Quality). Missing letters, wrong depths and wrong-side cuts all show here. To read a toolpath's depth, open it for editing from the toolpath list and check its Cut Depth.
2. Material thickness in Job Setup = actual measured stock (calipers, not the label, because "3/4 inch" plywood is not 0.75").
3. Z-zero setting matches how you will zero (top vs spoilboard) and XY datum matches where you will zero.
4. Toolpath depths vs thickness: through-cuts slightly over, everything else comfortably under. Tabs on cut-outs, visible in preview.
5. Right post-processor, right units (the post-processor must match your controller's units).

At the machine

1. Correct bit installed and tight (matches the toolpath's tool), collet clean and seated.
2. Stock secured. Shake-test it, and keep clamps clear of every toolpath (run your eye along the path, or use keep-out zones).
3. Machine homed, X/Y/Z zeroed per the file's convention, and spindle actually on before the cut starts (manual-start spindles bite everyone once).
4. Dust collection on, area clear.

First 30 seconds of the cut

1. Hover near the pause/stop control. Watch the first plunge and first pass, because wrong depth or position is obvious immediately and a fast stop saves the stock. Air-cut (Z zeroed high) any job you are unsure about.

Pro tips

• Multi-tool jobs: the checklist repeats at every tool change, with the right bit and re-zeroed Z (see that entry).
• Print or post this list at the machine until it is habit. Every experienced user's "stupid mistake" story is one of these items.