Mach 3 Rapid clearance question

Wondering why my rapid clearance dose not always work . It is correct in the G code Z of 1.00 and it always works when i dry run with torch turned off but with torch turned on it drags on the sheet even tho the g code is correct . Any ideas ?

I thought the Mach 3 machines didn’t have a powered z axis? Did you mod yours?

The Mach 3 plasma software dose I use sheet cam to generate the G code .

I thought the earlier crossfires didn’t have the powered z is what I meant.


welcome to the forum…

how old is your table?..
which table do you have?..
any table purchased from Langmuir in the last year runs on FireControl available from their site.

only the older Gen1 2’x2’ tables ran on Mach3

Does your table actually have a THC (powered Z axis). If not then you have the wrong post processor installed for Sheetcam.

If you have an original Crossfire, then the correct post processor is “Mach3 Plasma No Z” and Rapid Clearance is ignored.


Yes it dose have THC . When I run it with the torch off it lifts every time but with the torch on its hit or miss and its in the G code of 1 inch .

Did you install the THC yourself or is it a gen 2 FireControl system?
If the latter, then you need to use the Firecontrol PostProcessor for SheetCam. You can download this from the Supports page.
If the former then you’re kind of on your own unless you supply a LOT more detail as to what you have.

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Why would it work with the torch turned off and some times with it on ? Thats what confuses me .

It doesn’t move the Z the same during dry running.

As to why it doesn’t while running a program to cut, can you post a bit of the gcode from the beginning of your program for us to check?

Also, what CAM software are you using?

Without answering our questions, we also remain confused and, at this point, will never converge on an answer to your real problem.

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I use solidworks to design and export the DFX and sheetcam to post and Mach 3 to cut .

I use the same software except my Pro uses Firecontrol. Sheetcam has rapid clearance in the Job options tab. Make sure that isn’t randomly changing on you.

If you could post the first, say, 30-50 lines of gcode, or an actual gcode file that is giving you improper movement would be helpful to rule out a program problem.

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please answer the following questions with a yes or no…

did you buy your Crossfire plasma table from the Langmuir company?

did you buy the crossfire table in the last 14 months?

is your table the 2’x2’ table?

is your table the Crossfire Pro…48" x 32"?


This is all the sight will let me you. but look at line N0220 G00 Z1.0000 . Thanks

N0010 (Filename: dimond plate floor.tap)
N0020 (Post processor: Mach3 THC with scriber.scpost)
N0030 (Date: 02/04/2021)
N0040 G20 (Units: Inches)
N0050 F1
N0060 G53 G90 G40
N0070 (Part: dimond plate floor)
N0080 (Operation: Outside Offset, Colour 7, T1: T1 11 ga steel 90 IPM)
N0090 G00 X37.6234 Y0.6956
N0100 G28.1 Z0.12 F19.685
N0110 G92 Z0.0
N0120 G00 Z0.0591
N0130 G92 Z0.0
N0140 G00 Z0.1500
N0150 M03
N0160 G01 Z0.5000 F90.0
N0170 G03 X37.8044 I0.0905 J0.0905
N0180 I-0.5544 J0.5544
N0190 X37.8451 Y0.7396 I-0.5544 J0.5544
N0200 X37.8313 Y0.9201 I-0.0972 J0.0833
N0210 M05
N0220 G00 Z1.0000
N0230 X37.8044 Y17.6234
N0240 G28.1 Z0.12 F19.685
N0250 G92 Z0.0
N0260 G00 Z0.0591
N0270 G92 Z0.0
N0280 G00 Z0.1500
N0290 M03
N0300 G01 Z0.5000 F90.0
N0310 G03 Y17.8044 I-0.0905 J0.0905
N0320 I-0.5544 J-0.5544
N0330 X37.7604 Y17.8451 I-0.5544 J-0.5544
N0340 X37.5799 Y17.8313 I-0.0833 J-0.0972
N0350 M05