I've been looking for the right mill to buy to do a CNC conversion. It seems the Grizzly 0704 is the most popular for home shops with the RF45 a close second. Based on the success folks have had building the things they want to build with those mills, I'm sure I'd be happy with either. But what I would like to know is why not buy an older but much heavier and more powerful used mill from eBay for about the same money or not too much more. Can they be converted for CNC use? Or an old non-working dedicated CNC machine, could I just rip out the electronics and use the motors with new electronics?

What are the risks of buying an older or heavily used mill on eBay? Would wear and tear result in backlash that would make the machine inaccurate? Can you replace bearings and other critical alignment parts to restore or maintain the accuracy on an older mill like that?

Many of the listings say they were pulled from service working but there's no guarantee.

As I look at what it would take to rebuild an older mill like that I imagine I might want a mill, perhaps the 0704, just to have for using on the restoration of an older, larger, mill.

I'd really appreciate the thoughts and any advice from others who have done conversions and restorations on older mills or just from those of you who have more experience and thoughts on the topic.

Thanks.

Dale