http://cgi.ebay.co.uk/CNC-ROUTER-bal...item27b39b2f3c

This looks very tempting, the cost of ball-nuts and machining would come to more than the asking price :)

But :(
1500mm on a 16mm ball screw, I think this is asking to much of 16mm? Assuming 1 end tied the other supported.
Even using 2 1500mm x 16mm for the Y axis the speed would be compromised by the length and diameter? I'm still getting my head around whip!
Is a standard 3Nm stepper up to the job of driving a 1500 x 16?

I'm sure if the deal is a good one they will be gone by the time the above are answered, and if they are still there... Well...

If I chopped 2 (2 for Y axis) of the 1500s to say 1000 and chopped the 3rd 1500 to say 700mm (I'm sure I can borrow a grinder), is it then so difficult to grind a little and file (hand file of course) the ends down to 10mm?

Edit:
How did this end up in electronics ? My bad, sorry, was intended for general.