Advanced Search

another update

pgf wrote:

 Given that the length of the bit is variable, there is no single actual lower hardware limit. It depends on how far the bit protrudes from the collet. Given that, what's the use of the limit? When would it do me any good?

Adding an upper Z limit switch is usually pretty easy and makes it easy to use Linuxcnc as intended. eg Work in G54 offsets.
Normally, you would jog down so the tool touches the workpiece and set your g54 offset. 
Using work coordinates eg G54 was my biggest learning.

You have to remember you are dealing with cartesian coordinates.
You can home to any corner you wish. Homing to the lower left of the worktable means all x,y coordinates are in the positive quadrant.
Homing to another corner will mean at least one axis will count in the negative direction. Think of the graphs you drew at school

I did have a machine where the home switch was at max Y but I added a home offset to make the home position at min Y
Thinking about it after using it, I realized I could have homed it at the home switch position so the Y axis would count in the negative direction beecause once you zero G54 offsets at lower left on your workpiece, everything would count in a positive direction anyway.