Small holes on plasma: the settings that matter
Small holes on plasma come down to how the torch enters them. GCnester gives you a handful of controls for that, plus a way to refuse holes that are too small to cut. This guide says exactly what each one does, and what it doesn't, so you can set them from your own results rather than from folklore.
Under Small Holes, Threshold decides which inside cuts get the small-hole entry. Auto sets the threshold at twice the effective lead-in length, including any per-contour override. Absolute uses the number you type in Hole Size. A hole counts as small when it's smaller than the threshold, not equal to it. For a true circle the size is its diameter; for any other loop it's the smaller of its width and height, which is only an approximation for curved shapes.
Below It sets what a qualifying hole gets. Center Pierce pierces at the hole's centre and moves straight to the contour instead of using the normal lead-in. The hole is still cut at the job's speed and height; nothing about the feed or torch height changes. You'll see a Shorten To Fit option. Right now it doesn't actually shorten the posted lead to fit the hole, so don't rely on it; set a shorter lead on that contour yourself.
Tick Flag holes too small to cut and set Min Size. Any placed inside cut below that size stops G-code generation with a message asking you to set the hole to Ignore or Drill. Nothing is dropped or converted silently. This check is separate from the threshold above.
Lead type, length, arc radius and sweep, side, lead-out and overcut are set in the lead editor for the job and can be overridden on a single contour by right-clicking it. Those overrides change the entry geometry only. There's no per-hole speed or height setting: Cut Speed and Cut Height under Plasma Settings apply to every cut in the job, from the cut chart when Machine is ticked or from the values you type.
Every inside loop carries a role: Cut, Drill, Mark, Ignore or unassigned. Ignore leaves it out of the program on purpose. Drill needs a round hole and real drilling tooling in the job (a tool number, a down feed and retract heights); it doesn't make a plasma-only machine drill. The Marking and Drilling Tools pane is a read-only summary of what the job has declared.
When generation stops, the message names the problem: a hole below Min Size, a hole the kerf would consume entirely, a cut-path offset that failed, or a lead that could not be built. Check the contour's units and size, the chart and kerf, and the lead geometry, then choose a supported role. Ticking Shorten To Fit won't fix any of these.
Questions people ask
Not in the software. Auto threshold is based on lead length, not thickness. Whether a given hole cuts cleanly depends on your machine, consumables and settings, so test on scrap and set Min Size from what your table actually does.