Yes, the IH mill is definitely larger than the Tormach, but I believe the weight difference is more like 250 lbs. I've never seen the IH mill in person, but I'm glad I went with the Tormach instead. For one thing, I was able to just plug it in and go, vs. the IH where you need to tear the thing apart and install the CNC kit. Probably not a big deal if you have the time, but I don't right now... Also, I really don't think servos will give you any better resolution than steppers. You will get faster rapids, but you can always upgrade the Tormach if you fell like it...
Also, if you're looking for a high speed option, Tormach has a kit that hasn't been released yet to mount a high speed Proxxon grinder off to the side of the main spindle. I believe they run between 5-20k rpm with max .001 run out.
If I'm not mistaken, Mike Aber has both machines and has posted his impression of both in another thread here.
Dave |