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"Sharp Corners" rounded
« on: June 25, 2023, 09:13:23 PM »
Hello,

Any thoughts on what might cause corners to be rounded on a simple square profile cut?  The GCODE below was my test case.  The MACH toolpath display shows the square profile roughing toolpath and the actual path traversed shows rounded corners.

THoughts?

Lynn

G00 G20 G90 G17 G40 G80 G49 G64 G94
T1 M06 (ENDMILL ROUGH)
G90 S15000 M03
G54
G00 X2.14 Y9.86
G43 H1 Z1.
Z0.2
Z0.1
G94 G01 Z-0.125 F84.
Y6.14 F168.
X5.86
Y9.86
X2.14
G00 Z0.2
Z-0.025
G01 Z-0.25 F84.
Y6.14 F168.
X5.86
Y9.86
X2.14
G00 Z0.2
Z1.
(ENDMILL ROUGH)
G90 S15000
G54
G00 X2.125 Y9.875
Z1.
M08
Z0.2
Z0.1
G01 Z-0.25 F42.
Y6.125 F84.
X5.875
Y9.875
X2.125
G00 Z0.2
Z1.
M05
M9
G91 G28 Z0
G91 G28 Y0
G90
T1 M06
M30
%

Offline Tweakie.CNC

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Re: "Sharp Corners" rounded
« Reply #1 on: June 26, 2023, 01:14:26 AM »
Something to try…

On the first line of your GCode replace the G64 with G61.
This will invoke Exact Stop instead of Constant Velocity.

Run the Gcode file.
If your corners are now OK then you need to spend some time tuning your motors to obtain the maximum acceleration for the desired axis velocity. Refer to the Mach manual for details of these settings.

When you have your Velocity and Acceleration set correctly for each axis then you can return to G64 Constant Velocity mode.

Tweakie.
PEACE
Re: "Sharp Corners" rounded
« Reply #2 on: June 29, 2023, 11:08:59 AM »
Thanks Tweaky,

It ended up being total user error.  I had recently changed the post processor that snuck the G64 into the invocation section that you mentioned.  It being modal caused the same issues with g-code files that I didn't have issues with before, which is why I was puzzled.

Anyway, I removed the G64 reference in my postprocessor so the Mach setting is in control, and all is well.

Thanks for leading me down the right path.

Lynn

Offline Tweakie.CNC

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Re: "Sharp Corners" rounded
« Reply #3 on: June 30, 2023, 12:09:35 AM »
Hi Lynn,

I am pleased that you have it sorted.

Tweakie.
PEACE