Gas & Ignition Subroutines

o<fire_oxy_torch> call [preheat_height] [preheat_time] [pierce_height] [pierce_delay] [cut_height]
o<oxy_torch_off>  call

fire_oxy_torch owns everything between arriving at the pierce point and starting to cut. oxy_torch_off owns everything between finishing the cut and being clear. Between them the post writes only the cut path itself, so the subroutines own all Z motion — the posted program contains no Z words of its own.

The five arguments come from the cut chart row for the plate being cut, so one subroutine serves every thickness. Cutting 1/8 inch and 4 inch plate in the same program calls the same subroutine with different numbers.

The preheat flame set stays lit for the whole job — you light it and tune it by hand before the run, and Z0 is the plate surface, touched off once. From there fire_oxy_torch runs the sequence a flame torch actually needs:

1. Down to preheat height — the soak standoff, close to the plate.
2. Soak for the chart's preheat time, until the spot reaches ignition temperature.
3. Up to pierce height — clear of the slag blast before the oxygen hits, so the blowback doesn't foul the tip.
4. Cutting oxygen on — if the relay toggle is enabled (see below).
5. Feed down to cut height, burning through on the way. The chart's pierce delay is how long that descent takes; the subroutine computes the plunge feed from the heights and the delay itself. There is no inverse-time G-code and nothing extra to configure on the controller.

oxy_torch_off closes the oxygen (if enabled), settles, then lifts clear. Nothing probes or re-zeros — you set Z once, by hand.

The clearance height matters. Rapids between contours happen with the preheat flames still burning, at whatever height oxy_torch_off leaves the torch. Too low and they scorch the plate on the way across. Raise it until traverses leave no mark on your material.

Both templates carry a relay option, off by default:

• Off — for a hand-tuned two-hose torch. The operator owns the oxygen lever; the program drives only Z, and the chart's preheat and pierce values alone do the work. No configuration needed — this is how the templates run out of the box.
• On — for tables with a solenoid on a spare digital output. Enable the Oxygen Relay toggle in each subroutine's settings and set the output index in both: the fire subroutine opens the oxygen at pierce height, synchronized with motion, and oxy_torch_off closes it the instant each cut ends. If the machine also runs a plasma torch, put the oxygen solenoid on a different output than the plasma torch relay.

Auto igniters and staged fuel circuits still go in at the marked insertion points — ordinary G-code, no change to the post or the charts.

The fire subroutine's Dry Run toggle traces the full motion — soak standoff, raise, descent — while skipping the dwells and never throwing the relay, so you can prove a program's motion without sitting through minute-long preheats or opening oxygen over the plate.

The defaults are fire_oxy_torch and oxy_torch_off — distinct from the plasma pair (fire_torch / torch_off) so both can live in the same subroutine library without colliding. If your shop already has its own naming, change it on the post's properties; the post calls whatever you name there.

Related: Torch Selection & Cut Charts, G-code Post Processor.