I now think I have resolved my issues in UGS The problem was partly identified by a chap on another forum called “cncmakers001” who gave me a hint what to look for.
cncmakers001 wrote and I quote verbatim:-
“GRBL is very strict about arcs being precise and valid, whereas Mach3 and even some senders like Candle are more lenient or even approximate arcs as tiny line segments behind the scenes.”
This sent me into hunt mode where I looked more closely at my G-Code generator, CamBam. In depth analysis identified that a radius or arc was being generated to a staggering 16 decimal places, absolutely crackers but true !
That was not a problem if the decimal places were at zero but UGS would spit it out like a nasty taste if it was something
like 4.45807984715249
to resolve the issue I simply rounding up most of the trailing digits to within five decimal places.
I’m back in love with UGS its slick looks and its lovely features as I was about to venture on ripping out the GRBL controllers and replacing them with USB Mach3 boards.
Happy as a pig in Poo !