Quote Originally Posted by magicniner View Post
140mm under the collet nut isn't much space to fit a fourth axis into unless it's a really tiny one.
...but it is much more than most other eBay machines, and the majority of hobby machines have. Also, 100mm is what most 4th axis needs, so in general, for a hobby machine I think 140mm Z clearance is more than enough and is definitely not a "tiny one".