Cutter comp turns on cutter compensation for all of the passes of a milled feature. The rough pass requires a second checkbox to be checked as well, however, because it isn't always wise to use cutter compensation on the roughing pass (see below).
Cutter compensation is a feature of a machine control that will offset the lines and arcs of a toolpath to account for the difference between a tool’s actual diameter and the diameter that is entered into FeatureCAM. For example, the diameter entered into FeatureCAM might be 0.500, whereas the actual tool diameter, due to wear, is 0.496. Cutter compensation allows this difference to be accounted for at the control so that a single NC program can be used as long as the tool is close enough in diameter to the ideal size entered into FeatureCAM.
The default cutter comp setting for finish and semi-finish can be established in the machining attributes. The default setting for rough is always off.
The direction of the compensation depends on the value of Climb mill. If Climb mill is on, the cutter compensation direction is left, and right if off. For more information, refer to Part line program.
If you use cutter compensation you must enable this capability in the Post Options dialog box. Turning it on does not turn on cutter compensation for every feature, however, as cutter compensation NC code is output only for those features with the Cutter comp attribute set. If the Cutter Comp check box is not checked in the Post Options dialog box, then cutter compensation is disabled for the entire part regardless of the value of the Cutter Comp attributes on each feature.
If the user has specified both multiple roughing tools and part-line cutter compensation for the roughing pass, then in almost all cases bad NC code will be generated because in almost all likelihood the first roughing tool will be bigger than the arcs in the part. We would consider this to be a fact of life and the user will need to turn one or the other in order to get workable NC code.
If cutter comp is not chosen for the roughing, then no cutter comp will be output at all. This is important to note because there was a little known feature of V11 and earlier that if the finish allowance was 0 then the last pass of roughing would have cutter compensation turned on. So this is a behavior change from V11 and earlier. For V12 and beyond cutter comp on rough happens only when the rough cutter comp box is checked.
Cutter compensation for the roughing pass will result in only the passes closest to the wall to be compensated. The interior passes won't be compensated as there is no need.
If you check the Part line checkbox, then you will get a special kind of cutter compensation known as part line programming.
Read about cutter compensation posting errors.