Probing is one of the great basic functions of a CNC setup. Easily find the top, edges of you work piece, or even find the centre of a hole.
LinuxCNC is very customisable in this area, like most others, but unfortunately you need some probing code. Never fear, I've collected a few useful bits of code and some subroutines to make probing easy!
Have a look at my guide on a Z Touch Off Plate for LinuxCNC. This is very useful for routers and other machines that have no way of a repeatable Z height for each tool. With a router, each time you change tools you end up with a different tool length sticking out. With this simple code you just place your plate under the tool and hit a button.
Next up we'll get a bit more complex with a NGCGUI subroutine for finding the corner of a workpiece and the Z height (this one needs a probe rather than a touch plate). It's configurable with probing speeds, distances, safe heights, and final position.