G7 and G8 don't seem to change how the paths are read

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7 years 6 months ago #131894 by Vitran
G7 and G8 don't seem to change how the paths are read was created by Vitran
I am using BobCAD on a lathe. I tried to run code and noticed it was producing a diameter, not a radius, for the X value. When I was using CamBam before I changed it so X was 1/2 the diameter.

I found in the post processor how to change it from radius to diameter. It changed the G8 to a G7 at the start. With that change in the code, no difference. When I loaded it back into LinuxCNC it produced the same path lines with the radius=diameter.

I can go into MDI mode and do G7 G0X1 and G8 G0X1 and see it moving to 1" diameter and 1" radius. However not in the code. Changing the G7 and G8 at the start of the code does not change the paths on the screen. It will not let me start the code as it sees an arc with an excessive radius error.

Any ideas what I am missing?

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7 years 6 months ago #131905 by Todd Zuercher
Replied by Todd Zuercher on topic G7 and G8 don't seem to change how the paths are read
Posting the beginning of the gcode file would be helpful diagnosing your problem.

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7 years 6 months ago #131912 by Vitran
Replied by Vitran on topic G7 and G8 don't seem to change how the paths are read
I found the solution about an hour after I posted. Not really a solution, but here.

This is the start of the code that failed.
Code:
G20 G64 G40 G18 G7 G95 (TOOL #5 TRIANGLE FACE) T05 M6 G43 G90 S500 M3 G00 X.71 Z1.125 M8 G00 Z.325 G00 Z.075 G01 X.51 F.015 G01 X0. G01 Z.125 G01 X.1414 Z.1957 G00 X.71 G00 Z.025 G01 X.51 G00 X.931 G00 X.431 G01 Z.125 F.015 G01 Z-1.2726 G03 X.5156 Z-1.3125 I-.0247 K-.0555 G01 X.531

The code above would always have X value in terms of diameter instead of radius. It would fault on the G03 line as shown (I did truncate some of the code). What I changed was make the post processor export the G03 as a radius, or X,Z,R and that made the lines work in terms of radius instead of diameter.

Below are the two complete codes. The first did not work, the second did.
Code:
My Drive G20 G64 G40 G18 G7 G95 (TOOL #5 TRIANGLE FACE) T05 M6 G43 G90 S500 M3 G00 X.71 Z1.125 M8 G00 Z.325 G00 Z.075 G01 X.51 F.015 G01 X0. G01 Z.125 G01 X.1414 Z.1957 G00 X.71 G00 Z.025 G01 X.51 G01 X0. G01 Z.075 G01 X.1414 Z.1457 G00 X.71 G00 Z-.025 G01 X.51 G01 X0. G01 Z.025 G01 X.1414 Z.0957 G00 X.71 G00 Z-.026 G01 X.51 G01 X0. G01 Z-.025 G01 X.1414 Z.0457 G00 Z.325 G00 Z5. G00 X0. G00 X.71 Z1.125 G00 Z.325 G00 Z-.0362 G01 X.51 F.015 G01 X0. G01 Z.125 G01 X.1414 Z.1957 G00 Z.325 G00 Z0. G00 X10. G00 X2.51 Z.225 G00 X.931 G00 X.431 G01 Z.125 F.015 G01 Z-1.2726 G03 X.5156 Z-1.3125 I-.0247 K-.0555 G01 X.531 G01 X.6724 Z-1.2418 G00 Z.225 G00 X.331 G01 Z.125 G01 Z-.0529 G01 X.376 Z-.0754 G03 X.391 Z-.0935 I-.0362 K-.0181 G01 Z-1.2713 G01 X.4063 G03 X.431 Z-1.2726 I0. K-.0569 G01 X.5724 Z-1.2019 G00 Z.225 G00 X.2632 G01 Z.125 G01 Z-.019 G01 X.331 Z-.0529 G01 X.4724 Z.0178 G00 X.931 G00 Z5. G00 X0. G00 X2.51 Z.225 G00 X.8947 G00 X.2344 G01 Z.125 F.015 G01 Z-.0188 G01 X.2785 Z-.0408 G01 X.3619 Z-.0825 G03 X.371 Z-.0935 I-.0221 K-.011 G01 Z-1.2813 G01 X.4063 G03 X.4947 Z-1.3125 I0. K-.0469 G01 X.6361 Z-1.2418 G00 X.8947 G00 X10. G00 Z0. M5 M9 M1 G8 G0 X3 G0 Z4 M5 (thread) t3 m6 g43 s600 m3 g4p1 g0z.2x.1970 g76 p.0625 z-1.0 i-.0025 j.008 k.05 h3 r2.0 q29.5 e.07 g0x3 g0z4 m5 M30
Code:
My Drive G20 G64 G40 G18 G7 G95 (TOOL #5 TRIANGLE FACE) T05 M6 G43 G90 S500 M3 G00 X.71 Z1.125 M8 G00 Z.325 G00 Z.075 G01 X.51 F.015 G01 X0. G01 Z.125 G01 X.1414 Z.1957 G00 X.71 G00 Z.025 G01 X.51 G01 X0. G01 Z.075 G01 X.1414 Z.1457 G00 X.71 G00 Z-.025 G01 X.51 G01 X0. G01 Z.025 G01 X.1414 Z.0957 G00 X.71 G00 Z-.026 G01 X.51 G01 X0. G01 Z-.025 G01 X.1414 Z.0457 G00 Z.325 G00 Z5. G00 X0. G00 X.71 Z1.125 G00 Z.325 G00 Z-.0362 G01 X.51 F.015 G01 X0. G01 Z.125 G01 X.1414 Z.1957 G00 Z.325 G00 Z0. G00 X10. G00 X2.51 Z.225 G00 X.931 G00 X.431 G01 Z.125 F.015 G01 Z-1.2726 G03 X.5156 Z-1.3125 R.0568 G01 X.531 G01 X.6724 Z-1.2418 G00 Z.225 G00 X.331 G01 Z.125 G01 Z-.0529 G01 X.376 Z-.0754 G03 X.391 Z-.0935 R.0256 G01 Z-1.2713 G01 X.4063 G03 X.431 Z-1.2726 R.0569 G01 X.5724 Z-1.2019 G00 Z.225 G00 X.2632 G01 Z.125 G01 Z-.019 G01 X.331 Z-.0529 G01 X.4724 Z.0178 G00 X.931 G00 Z5. G00 X0. G00 X2.51 Z.225 G00 X.8947 G00 X.2344 G01 Z.125 F.015 G01 Z-.0188 G01 X.2785 Z-.0408 G01 X.3619 Z-.0825 G03 X.371 Z-.0935 R.0156 G01 Z-1.2813 G01 X.4063 G03 X.4947 Z-1.3125 R.0469 G01 X.6361 Z-1.2418 G00 X.8947 G00 X10. G00 Z0. M5 M9 M1 G8 G0 X3 G0 Z4 M5 (thread) t3 m6 g43 s600 m3 g4p1 g0z.2x.1970 g76 p.0625 z-1.0 i-.0025 j.008 k.05 h3 r2.0 q29.5 e.07 g0x3 g0z4 m5 M30

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