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Learn/Plasma/Rules Engine

Contour Rules

Updated v2.5.2

At a glance

  • Machine and cut-chart rules apply by material thickness, contour type, perimeter, or circular-hole diameter
  • Stack feed, voltage, pierce, lead, THC, skip, spot, peck, and custom G-code actions
  • Matching rules combine in order: percent overrides multiply and later absolute overrides win
  • Rules are reversible — disable a rule and regenerate to restore the underlying settings
  • Rule-colored contour overlays show affected geometry, including skipped contours
  • Operation Type overrides let selected holes use Auto, Drill, Center Pierce, Peck Mark, or Cut normally
  • Peck Mark creates drill-locating divots using the pulse time and height in Cut Parameters
  • Supported current firmware and fire_torch routines verify arc strike and retry peck misfires

Contour rules change how individual contours cut based on their geometry — slow down small holes, kill THC on short perimeters, skip a contour entirely — without touching the part. Define them on the machine profile (the + Cutting Rules button in the sidebar, or Machine Configuration → Rules) or on an individual cut chart, where they apply only when that chart is active. Rules are evaluated fresh every time you generate toolpaths.

Conditions

A rule matches contours by Hole Diameter (true circular arc holes only — a rounded rectangle or polygon never reports one), Contour Type (hole, outer, or open), Material Thickness, and Contour Perimeter (arc-aware length). Numeric conditions take <, ≤, >, ≥, =, ≠, or between, and a rule can stack several conditions that must all hold. Use ≠ (is-not) to target everything except one value — set Contour Type ≠ Hole and the rule applies to every contour but holes.

Actions

Matched rules run their actions top to bottom: Feedrate, Arc Voltage, and Pierce Delay overrides (percent or absolute), Custom G-code inserted before or after the cut cycle, Disable THC for the whole cut or a set distance before the end, Skip (no toolpath, no post output — the contour drops out of pierce counts, cut time, and quotes), Center Spot Pierce (pierce-only marking for circular holes; requires hole diameter as the sole condition), and Lead Override for per-match lead-in/out geometry.

Marking one hole for the drill

A rule keyed on hole diameter marks every hole that size on the sheet. When it's a single hole on a single part — a bore that has to be accurate, so it gets drilled and bored on the mill rather than cut — right-click the hole and pick it under Operation Type.

The submenu has four states. Auto (rules) is the default and leaves the decision to your rules. Drill / Center Pierce marks the hole whether or not a rule caught it. Cut normally forces a cut on a hole a Center Spot Pierce rule did catch — the way out when a rule is right for the sheet but wrong for one hole. Whichever you pick beats the rules, and Reset Overrides returns the contour to Auto.

Unlike a rule, this is a permanent property of the contour: it saves with the job and survives regeneration. Press C for Contour Select to mark several holes at once, and the setting carries to every copy of the part on the sheet. Marked holes show the same green X as rule-driven ones, sized to the hole, and post with the diameter named so whoever picks up the blank knows what to drill. Pierce timing comes from the cut chart unchanged.

Peck marks — the torch as a center punch

A center spot pierce is still a full pierce: the torch waits for the arc to establish, which on thin material can blow the hole through before the mark is a mark. A Peck Mark fires the torch for a short fixed pulse — 10 milliseconds by default, adjustable from 1 to 1000 — and shuts it off on the timer, never waiting for arc-OK. What's left is a small, repeatable crater at the hole's exact center: a drill-locating divot, made with the same touch-off cycle as every pierce so the position is trusted.

Mark a hole the same two ways: right-click → Operation Type → Peck Mark for one hole or a Contour Select set, or add a Peck Mark action to a rule keyed on hole diameter to catch every matching hole on the sheet. The pulse time and peck height are set once in Cut Parameters → Peck; a rule uses those values by default, or unchecks "Use Peck Cut Parameters" to carry its own. The pulse is timed by the machine controller itself at millisecond resolution, so it stays exact regardless of USB or network hiccups, and posted code announces each mark with the hole diameter and pulse length.

The pulse time is how long the arc burns — and the controller now guarantees it. Closing the torch relay doesn't light an arc: your supply purges gas and strikes a pilot first, which varies from supply to supply and even fire to fire — a warm torch with gas still moving restrikes far faster than a cold one, and some supplies need the start signal held for over a second before they'll light at all. Instead of asking you to budget for that, the controller fires the torch, watches the arc voltage for the actual strike, then holds the arc for exactly your pulse time and shuts off. The same peck number makes the same divot on any machine, cold or warm, with no per-machine tuning. As a bonus, every peck records how long your supply took to strike, at millisecond resolution, in the machine's serial log.

Pecks catch their own misfires

Because a peck never waits for arc-OK, a misfire used to be silent — the program moved on and you found the missing divot at the drill press. On AVTHC machines every peck proves itself: the strike is detected as the measured arc voltage clearing the Peck Verify Voltage threshold (Machine Configuration → Subroutines → fire_torch; 40 V out of the box, 0 keeps the old relay-timed pulse), watched at the controller's full sample rate so even a few-millisecond mark can't slip past. If no strike comes before the Peck Arc Wait Timeout (3 seconds out of the box — enough to cover the slowest cold start), the torch shuts off and the peck is silently re-fired in place, up to the same retry count a failed pierce gets. Re-fires are paced by a Peck Retry Recovery delay (1 second out of the box) so your plasma supply's own restart lockout has passed before the next strike. And because the controller waits for the strike rather than judging a fixed window, a slow-lighting supply reads as a slightly late mark — never as a misfire that retries into a live arc and blows the hole. If the torch truly won't light, it retracts and shows the familiar check-your-consumables prompt — Continue retries at that same peck, Stop aborts. A mark is never silently skipped. Requires the current controller firmware and a fire_torch re-import; your saved parameter values carry over.

This needs the current machine firmware (the Flash Firmware dialog offers it) and a re-import of the bundled fire_torch subroutine — the Subroutines page shows its update badge, and your parameter values survive the swap. Without either, pecks behave exactly as before.

How overlaps resolve

Machine rules evaluate before cut-chart rules, and feedrate percentages never compound: each percent applies to the base cut-chart feed, the last match wins, so a chart rule overrides a machine rule. When two feedrate rules collide, Generate names both rules and the winner in the error indicator. Rules are transient — disable or delete one and regenerate, and the contour returns to its cut-chart settings. After generation, matched contours get a bold edge overlay in each rule's color (skipped contours included) so you can verify what fired; separately from rules, holes too small for the configured arc lead get a soft-entry center pierce, and JetCad3 asks once per run before converting them.