Cutter radius compensation and Z moves

[petri-ju]

Hi

In general, is it allowed to make Z axis movements when cutter radius compensation is active (in XY-plane)? In all examples I have seen, radius compensation is cancelled before Z moves, but I don't know if it has to be cancelled. My opinion is that Z position should be possible to move and it should not change cutter X and Y positions, but does anybody have better knowledge?

If it is allowed, is it still a bad practice?

Machine is normal 3 axis milling machine.

-Petri

[txcncman]

Most newer CNC mills (about 25 years?) will allow Z axis movement with cutter compensation still enabled. The reason you usually see cutter compensation disabled in most programs is it allows the tool to be repositioned back to the starting point of repeating a pattern without thought for the tool path between the finish position and the start position. It is not bad practice to leave cutter compensation enabled. It is more difficult on the part of the programmer, which means it usually take more thought energy and time. It is easier to cancel, G40, rapid tool up, rapid back to the starting point of the pattern (a known number instead of calculating a new one), feed back down on Z, the copy the previous cutting pattern, repeating as many times as needed. It is also easier to cancel cutter compensation after each pattern, because forgetting to do so can create other programming problems later in the machining. Finding those errors out later takes more time and effort than just canceling the cutter compensation to begin with.

[sinha_nsit]

What one should keep in mind is a Z-move is not an XY-move (!). Two or more consecutive non-XY-moves would result in incorrect machining in radius compensation mode.