What to look for when buying an old milling machine, with the view to CNC it?

[Apples]

SO, you can ofter see the old milling machines for sale in the paper or ebay or at auctions etc. Assuming that the main purpose was to buy one and CNC it what parts need to be checked so that the accuracy is still good?

I guess the lead screws don't matter as I would put in new ballscrews. But do the ways, (the metal bit it slides on) wear out?

Do most people when converting to CNC just add new linear rails as well as ballscrews?

Trying to see if it is worth buying a new machine for say 13K or an old bombed out one for 2-3K and if you have to put in new ballscrews and linear rails etc, why spend 13K when I could save money etc, know what I mean?

Any thoughts or advise on this?

Cheers
Peter
Australia

[Belding]

Not to discourage you from building a machine, but have you seen this: http://www.tormach.com/Product_PCNC_main.html
Pretty cheap

zac

[Apples]

Hi,
Yeah I have seen the Tormach.

But I'm in Australia its proabably in the states, shipping would kill me.

By the time It went through currency conversion, shipping, customs duty and GST it would be too much.

I could build a bigger more powerfull machine for the same price or less.

Peter

[Al_The_Man]

Often at auctions, the older manual machines fetch more than younger CNC machines with tired controls.
By getting a deal in this way, at least you have a machine that is CNC ready.
For larger machines, ballscrew prices can be prohibitive.
Al.