Since I recently updated my grbl to 1.1f I was able to take advantage of G38.2
I use this as a macro in UGS
G38.2 z -.5 F1; G92 Z .065; G0 z .25
G38.2 Z -.5 F1
probes down .5 inch at 1 inch/min
G92 Z.065
sets Z to touch plate thickness (I use a copper clad pcb .065 thick)
G0 Z .25
retract tool
Position the tool at .5 inch or lower above touch plate (or change the Z higher if you like, keep in mind that it probes down at 1 inch/minute)
Run the macro. The tool will descend at 1 ipm until contact, then retract.
The value of Z0 will now be set at the material height.
I cannot take credit for this code, its floating around the web from several sources. I just put it all on one line in a UGS macro. Works great though!
I was interested in Triquetra. I really like his design for the touch plate. I would make my own but I only cut woods and plastics.
I have noticed 1,1 occasionally doing something strange with touch off code. I occasionally retracts when it should probe. If you try to probe without having homed the machine it will mess up. I dont know if homing only has to be done once, at the beginning of a job, or if the problem reoccurs later. I will be doing some experimentation this weekend
I havent had any problems with the Triquetra. I use it constantly. I home my machine at the start of each day and use the Triquetra every time I change a bit.
Question about the UGS nightly build. Do I have to download a new one every once in a while, or does it update? Looking at the file dates, it appears my nightly build of the normal version was last updated in 2015. So I assume I need to periodically download a new nightly build. I plan on giving the platform version a go pretty soon.
I am using 1.09. I downloaded the nightly build of the classic, but it only has 3 macros. Otherwise it seems to work fine. I just wish it had more that 3 macros.
I have tried the UGS platform, it works fine except I cannot figure out how to get the Macro function to work at all.
I have been using Triquetra with Intelligcode by Software Redifined. Intelligcode has those functions built in, but each axis must be done individually. I inserted the triquetra gcode as a macro and all works great.