Hi,
Mach4Hobby has CSS.
I suspect though that it suffers from the same fault that Mach3 does.
Mach3, according to the thread Hood linked to, makes a pretty fair approximation to constant surface speed
but cannot do Feed per Rev accurately. As was pointed out for Feed per Rev to be accurate requires that the spindle
be synchronized with the X axis and that is incompatible with buffered control system.
Mach4, despite it differences, is still a buffered control system and therefore probably not capable of accurate Feed per Rev
for exactly the same reason as Mach3. I have not tested it an Mach4 nor does my setup allow for it to be tested. I would
caution that if you require accurate Feed per Rev then Mach4 warrants investigation.....
Accurate Feed per Rev can be obtained by a C axis as opposed to a free running spindle. This is certainly capable of being
done in Mach4 and I can't imagine any reason that it could not be done in Mach3 as well.
Craig