Irving, that's a most useful post - I'm going to bookmark those calculations for future use..., thankyou.

I recon Irving's hit the nail on the head with
The question I suppose is...
The meaning of mid-level could be very different depending on who you're talking to. Although both of these chaps has built/converted a machine to run with EMC2, you'd probably get a different answer about "mid-level" from each... :)

[ame="http://www.youtube.com/watch?v=LA5qCIB0j6k"]YouTube- Fresa CNC MDF[/ame]
[ame="http://www.youtube.com/watch?v=mxxdq6y8z8M"]YouTube- EMC2 5 axis cinci at MPM[/ame]

So how about a list of variables, so that we can discuss pros and cons?

(low-spec -> high-spec):
* Working size (min A4 -> max 4ft x 8ft flat sheet)(Z depth?)
* Linear bearings (unsupported rails -> skate bearings -> v bearings -> supported round rails -> recirculating ball carriages)
* Drive method (chain/allthread -> belt/trap screw -> ballscrew)
* Target cutting speed vs. target resolution (trade-off)
* Rigidity & strength (just cut alu, or rip through it in a breeze?)
* Spindle type and power (dremel -> 43mm router -> handheld router -> VFD spindle)

Probably loads i've missed, so copy paste and add/change bits...

On my wishlist would be the ability to add a 4th axis (parallel with x) at some future time, without hacking the machine to bits. Designed in expansion capability if you will...