I am having a problem with the RPM two machines are running at in relation to the SFM command on the G96 line. It seems this is only happening with low SFM. For example when machining at say a 12" dia at 80 SFM my command line is G00 T0101, G96 S80 M08, G50 S350 M03. When I move the tool into the cutting position the RPM is running at 50 RPM. When I check the correct RPM by using this formula (12 x 80 SFM) / (Pi x 12" dia being cut) it should only be 25 RPM. I am getting round it by controlling the max RPM on the G50 line. This is ok when I don't have a huge variation from the starting point of cutting to the final dia being cut when using a G71 canned cycle but obviously doesn't work well when facing with a G72 cycle as the speed needs to increase the closer get to the centre of the job. Any ideas?