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Machine thinks plate is off table. Confused. Please help
« on: March 06, 2020, 12:23:03 PM »
Hi all,

The company I work for just bought a trucut CNC machine running Mach 4. Here is a rundown of the steps leading to the problem:

*Loaded DXF in sheetcam (simple shape w/ no holes) added operation to cut outside perimeter
*Set job options with a 4X8 sheet
*Set start point for lower left hand corner of part
*Nested about 1,1
*Ran Post processor to produce g-code file
*Used "ref all axis" to home the torch head
*Jogged to the lower left corner of the plate (approx 12,12) and "zeroed all axis to set work zero.
*Loaded g code file created in sheetcam
*Set for dry run and hit "cycle start g code" to run

Here is the issue:
*Torch head runs all the way to the positive side of the y axis and hits the limiter

The program seems to think the plate is off the table. Or that the start point is off the table.

What am I doing wrong here?

Thanks!

Paul

Re: Machine thinks plate is off table. Confused. Please help
« Reply #1 on: March 06, 2020, 01:51:34 PM »
Hi,
can you post an excerpt of the Gcode, the first 50 or so lines?

Craig
My wife left with my best friend...
     and I miss him!
Re: Machine thinks plate is off table. Confused. Please help
« Reply #2 on: March 06, 2020, 02:23:42 PM »
Hi,
can you post an excerpt of the Gcode, the first 50 or so lines?

Craig

Yes sir. Here you go

(Filename: 1056-6.nc)
(Post processor: TruCutCNC_Rev9B.scpost)
G20 (Units: Inches)
G90
G91.1
M1100
M1111
G00 X5.8502 Y2.2120
(Part: 1056.nc)
(Layer: Holes Pierce#: 1)
(Run From Here Start Point)
M1115
M14 A0 B30 C1
G01 X5.8880 Y2.0980
G01 X5.9005 Y2.0601
G03 X5.9005 Y2.0601 I0.1205 J0.2399
G01 X5.9641 Y2.0680
M15 A0 B30 C1
M01
G00 X2.8502 Y2.2120
(Part: 1056.nc)
(Layer: Holes Pierce#: 2)
(Run From Here Start Point)
M1115
M14 A0 B30 C1
G01 X2.8880 Y2.0980
G01 X2.9005 Y2.0601
G03 X2.9005 Y2.0601 I0.1205 J0.2399
G01 X2.9641 Y2.0680
M15 A0 B30 C1
M01
G00 X-0.2940 Y0.0000
(Part: 1056.nc)
(Layer: OuterContours Pierce#: 1)
(Run From Here Start Point)
M1115
M14 A0 B100 C1
M1101
G01 X-0.1740 Y0.0000
G01 X-0.0440 Y0.0000
G01 X-0.0440 Y3.8500
G02 X0.0000 Y3.8940 I0.0440 J0.0000
G01 X9.0421 Y3.8940
G02 X9.0861 Y3.8500 I0.0000 J-0.0440
G01 X9.0861 Y0.0000
G02 X9.0421 Y-0.0440 I-0.0440 J0.0000
G01 X0.0000 Y-0.0440
G01 X0.0000 Y-0.1440
M15 A0 B100 C1
M01
M1109
M1105
G00 X0 Y0
M30
(Total Pierces: 3)
(Total Cut Length: 30.163711314758)
(33:65A:1/2in:Steel:65A:0.18:0.06:1.2:100:132:PLASMA)
Re: Machine thinks plate is off table. Confused. Please help
« Reply #3 on: March 06, 2020, 02:53:13 PM »
Hi,
I would start by stripping the program down to its basics and adding lines until the fault occurs.
For example:

Code: [Select]
G20 (Units: Inches)
G90
G91.1
M1100
M1111
G00 X5.8502 Y2.2120
(Part: 1056.nc)
(Layer: Holes Pierce#: 1)
(Run From Here Start Point)
M1115
M14 A0 B30 C1
G01 X5.8880 Y2.0980
G01 X5.9005 Y2.0601
G03 X5.9005 Y2.0601 I0.1205 J0.2399
G01 X5.9641 Y2.0680
M15 A0 B30 C1
M01
G00 X2.8502 Y2.2120

m30


I have stripped the code down to the one operation.
What do M1100, M1111 and M115 do? Are you sure that one of these macros is not causing an overlimit excursion?

By the way, the Mach4 Gcode interpreter converts all Gcode to lowercase, strips out leading zeros and whitespace so
the interpreter is looking for m1100, m1111 etc. In most cases because Windows is case insensitive it will provide the
correct macro but you should get into the habit of writing ALL Gcode in lowercase. There are occasions when Mach will not
get the correct code because of the uppercase/lowercase thing and its a devilishly hard fault to pick.

The next issue is that I see your post has inserted a G91.1 line to ensure incremental arc mode. Is your machine set up that way?
If there is a clash of arc mode interpretation between the Gcode and the machine overlimit excursions are not unlikely.
Having said that the tool path display usually shows an errant tool path. Does in fact the tool path display show the
overlimit excursion?

You might test this theory by commenting out the 'G03 X5.9005 Y2.0601 I0.1205 J0.2399' line and running the program fragment
without it.

Craig
My wife left with my best friend...
     and I miss him!
Re: Machine thinks plate is off table. Confused. Please help
« Reply #4 on: March 06, 2020, 03:46:58 PM »
Hey Craig I will try this next. On thing to mention is that the machine even does this with the included shape generator. We did manage to cheat it by releasing the air and manually moving the torch down in the Y direction and then re-engaging the air..