1

**General Mach Discussion / Large circle problem**

« **on:**November 01, 2007, 01:02:26 PM »

Howdy,

We are having a problem cutting a circle with approximately 12" radius. The item is a circular tool that needs to be reduced in diameter for better fit. Our table has a y-axis travel limit of 15", so we are cutting a little more than half of the part at a time, then rotating 180deg and running the toolpath again.

The toolpath begins at the proper radius (12.24"), but as reaches the midpoint (X0) the radius is reduced to 12.2137", as it reaches the end of the toolpath the radius is back to 12.24". We have tried this with backlash comp. on and off, CV on and off, and even ran a sim on other computers. The mechanical counters on our machine confirm our DRO's so we don't believe we are completely crazy. (yet)

%

N100 G20

N102 G0 G17 G40 G49 G80 G90

N104 T239 M6

N106 G0 G90 X12.234 Y-.3823 S1069 M3

N108 H239 Z2.

N110 Z.35

N112 G1 Z-.005 F6.42

N114 G3 X-12.234 Y.3823 R12.24 F10.

N116 Y-.3825 R12.24

N118 G1 Z.095 F6.42

N120 G0 Z2.

N122 M5

N124 G0 X0. Y0.

N128 M30

%

Thanks in advance for any help.

We are having a problem cutting a circle with approximately 12" radius. The item is a circular tool that needs to be reduced in diameter for better fit. Our table has a y-axis travel limit of 15", so we are cutting a little more than half of the part at a time, then rotating 180deg and running the toolpath again.

The toolpath begins at the proper radius (12.24"), but as reaches the midpoint (X0) the radius is reduced to 12.2137", as it reaches the end of the toolpath the radius is back to 12.24". We have tried this with backlash comp. on and off, CV on and off, and even ran a sim on other computers. The mechanical counters on our machine confirm our DRO's so we don't believe we are completely crazy. (yet)

%

N100 G20

N102 G0 G17 G40 G49 G80 G90

N104 T239 M6

N106 G0 G90 X12.234 Y-.3823 S1069 M3

N108 H239 Z2.

N110 Z.35

N112 G1 Z-.005 F6.42

N114 G3 X-12.234 Y.3823 R12.24 F10.

N116 Y-.3825 R12.24

N118 G1 Z.095 F6.42

N120 G0 Z2.

N122 M5

N124 G0 X0. Y0.

N128 M30

%

Thanks in advance for any help.