I dont know what machine you are planning on getting but i can speak from my experience using a Mazak With the mazatrol programming software. It only had a C axis and live tooling.
I did retrofit and repair work for papermills and medical device manufacturers and also frequently cut keyways from 3/16 up to 3/4 on this machine. I just used the sharpest endmill i had (usually a whisperkut) and took between .01 and .04 depth of cut with a conservative plunge rate. The keyways came out great but the were not "precision". You could get +/- .001 but it wasnt always predictable. I always just used CRS square stock and made my keys to fit by honing them to the correct dimensions.
So i guess your answer is, If you can afford the live y-axis then get it. If your keyways can be worked around a thou or two then dont bother you can deffinately do without it. There are some times that it can come in handy but for the most part, a job shop wont need it. Besides your probably only gettings +/- 4" of travel right?  |