Can I ask what your priorities are - is it size, cost, rigidity or ... ? The reason I ask is because the projects you linked to (not sure which one you intend to make from the first link) should work on most mini-mills so anything is fair game. To home in on the right mill for you, you have to define things better.
For a bench top hobby mill, I suggest thinking about:
- Z-travel: this determines how big you can go, not so much table size. Just the vise alone will chew up some of this space so the more you have, the better.
- Table travel in X and Y: this determines how big you can go, too.
- HP: the more, the better. For a hobby mill, I think about 1HP is the least I would go.
- Spindle mount: R8 spindles allow you to use the vast majority of the accessories on the market.
- Spindle speeds: the higher, the better. A VS motor is really nice to have but if not then gears/pulleys that allow you to go real slow for big cutters and real fast for smaller cutters is good.
- Mass: I think the minimum would be somewhere in the 400# range. Mass makes a difference, especially when taking deeper cuts and when boring.
- Spindle travel: 5" is better, although 3" would be more common on smaller mills.
- Spindle bearings: precision tapered roller bearings is better than cheap, Chinese bearings.
Personally, the smallest mill I would even consider would be the PM-727M. It is big enough and featured enough to meet the needs of most hobby shops at a fair price. Of course, there are bigger/better mills but I would look at this as a good entry level machine.
By the way, I own a Sherline 5400 mill and it is much, much better than its size would suggest. I would put it up against much larger mini-mills, especially where accuracy is concerned. However, it is a small machine and trust me; mass tells.
