Originally posted by JamesBond
Also an important thing to remember when manually programming G41/G42 is that before your cut, you need to enable the G41/G42 with a move that is at least 1/2 the cutter diameter. This also goes for turning off cutter comp with a G40.
You might get some unexpected results if you try to turn cutter comp on with your first cut.
-JamesBond |
Good point, James.
BTW, for the uninitiated, this is what we machinists refer to as "an approach", that extra bit of toolpath that we add onto the actual part toolpath, to give the machine a chance to apply cutter compensation without forcing the tool into the wall of the part (gouging we call it), before the machine can figure out which side of the path it is supposed to be on. The reason the machine doesn't know how to apply compensation from a standstill, is that left and right are meaningless until a move is made down a path. In other words, there is no left or right to a starting point, but there is left or right to a starting movement.
A lot of this depends on how smart your controller is. If it can "look ahead" in your program before executing any movement, it may be able to apply compensation quite intelligently.
Nonetheless, at minimum, the machine
is going to have to move your commanded amount from your compensation table before it is on path. Whether it makes this move all by itself when it reads a G41/G42, or combines it with the first linear/circular) movement, it has to do something to get the cutter in position. This is why the first entity in your path must be either "in the waste", or "in the clear".