I will state the obvious then. Since you have experience and machines already, then you know milling creates a dirty environment. It is extremely difficult to seal ways off from just swarf even if you don't intend to use coolant. The motors you linked specifically say for light loads, so you are looking for some semi high speed machining? Very light repeat cuts?
These motors certainly appear fast enough. If you take very light cuts, they may do, but at a premium price. I don't have experience with linear's but I am curious how well these might work on the Z, which would carry some weight on it with the spindle.
Here are some relatively cheap spindles.
http://www.homeshopcnc.com/page7.html
I imagine they are for light duty cutting like what you intend. As opposed to hogging off metal.
I was finally able to design and built a mill myself. Just a standard benchtop size mill. The entire machine was likely around $5000.
I did manage to get 6600 RPM on my spindle. Just a standard X2 Chinese made mill head and tread mill motor with timing gear and belt drive. The entire spindle setup was well under $500.
I normally run the machine @ 200 IPM rapids, but set it to 300 yesterday. It would do 350 for certain, but this is pretty dang fast for such a small machine.
I have 14" x 9.5" x 9" travels. You want to move yours much faster. I am using preloaded precision ground ball screws and nice beefy THK linear ways.
My motors are 495 oz running off 72 VDC @ 12 amp PS and Gecko 203V's set for just 3 amps.
Bigger motors and more amps might push this machine up to a speed you could live with. Not sure though.
At any rate, I look forward to seeing what you come up with. The wheel has been reinvented a lot on this forum and most still roll well.
