I recently had a project that would have benefited from a 4th axis. I was able to work around it, but it shows me that I need to invest in one for future projects. I see Tormach offers the MicroARC. I also saw in the forum about not using anything bigger due to the clearances. Are there cheaper 3rd party options that work with the 440 and PathPilot, or is the MicroARC the only one that will work? Something with a live center on the other side would be preferable for longer, thin aluminum parts that I expect to cut on it.