Hi all,

What kind of accuracy in term of roundness can one expect from the 1100? We make custom motor/generator that spin at 6000+ rpm and needs to hold about .001-.0015". When cutting round parts on the Tormach, they are out of round by almost .004" when measure with a test dial indicator mounted in the spindle. This is when cutting a 6" circle using Pathpilot's Profile feature under conversational. It was off by .006" before leveling the mill using a precision bubble level, and the perpendicularity of x/y was also off by .004" for a distance of 100mm. Now it shows about .001" for 150mm which is a big improvement, but roundness still not acceptable. Lost motion is less than.001" for both x and y. I have been able to workaround the roundness issues using a boring head, but this does not work for non round features of a part. I haven't tried adjusting the gibs again after leveling the machine as lost motion for y was a bit over .001" before, but now it's less so maybe the gibs is loose?

Am I expecting too much from the machine? Has anyone tried cutting a big circle and measure their roundness to see how off they are? Can upper level machines like Haas mini mill hold .001" roundness cutting big circle?

Thanks