Losing steps - why?

[ljdm]

Here's a question for the pros - why would I lose steps x-axis with a 1/16 ballnose going 1.7ips taking .03 per pass, but not lose any with a 1/4 end mill going same speed but taking at least .25 per pass? Seems like the load on the 1/4 is a lot greater at that speed than on the 1/16.

[richards]

Lou,
How much of an error do you have? If you cut a straight line 6-inches long with each cutter, what are the final sizes after adjusting for the radius of the cutters?