Cutting circle is larger than expected, help!

[jbrass]

Ok, so I have my first CNC machine running.  but I noticed that when I am cutting a 12.7 mm radius circle, the radius is 1/16 larger it's cutting.
Do I need to compansate in my G code for the tool radius or diameter. Do I need to set a tool offset, how do I do that, if this is the issue?
John  

[jbrass]

Ok, I adjusted the g code to cut a 12.7mm (1/2") circle by adjusting the radius and it works, but there must be a better way to do this.
g02 X6.35 y61.9125 I4.762 J0  (4.7625 radius)

[BR549]

THe machine coords are calculated from the spindle centerline. SO you either have to acccount for the tool radius in the Gcode OR use tool comp to offset the Gcode.

Time for a reading of the manual.

(;-) TP