Hi I'm a newbie here.  I have a Taig CNC and Rhicam.  I set Feed Rate at 800mm/min with 10k RPM on Spindle.  
According on calculation on Rhino Cam, running time should 1 hour 28 min.  However, when I upload to Mach3 Estimate Program Run time is 6 hour 30min  instead.  
What is wrong here?

Rhino is calculating the time on the parameters it has set and Mach is calculating the time on the parameters it has set and there is a good chance that the two lots of parameters are not the same.
For example acceleration settings can make a huge difference in the GCode program run time even if the set feedrates between Rhino and Mach are the same.

Tweakie.