I'm just curious (not trying to be critical) as to why one would want to run a CNC machine with an Arduino when it's relatively easy and inexpensive to simply use EMC2? I run this very powerful and capable software on a 10 year old Pentium 4 machine I got for free so my software and computer costs are zero. The EMC2 community is very active and supportive and development of the software is constant in response to the users needs. Couldn't ask for more!