OK, the recent activity has re-inspired me to do my CNC mill project. As I understand it, a CNC mill differs from a router primarily in precision and rigidity...it's a machining setup, more than a woodworking setup. I still have no aspirations beyond brass and aluminum, but a smaller and more rigid machine would be nice for light metalworking and extra-hard woods.
JCK's Hawk project is a good example of what I'm calling a mill.
Well, a while back I bought a small cross slide vice for just this purpose. It should provide a reasonably precise X-Y setup, and as it's made from cast iron with dovetailed ways, it should be very stiff and very good. Roughly 4x6" of travel.
It's a cheap Chinese unit, but the price was right ($20), and with some work it should make a good and cheap unit. Primarily new lead screws (I'm upgrading to hardware store allthread!) mounted in BEARINGS, and some adjusting/tightening of a few parts. It's a pretty well designed little unit, but with a few minor problems...like poorly designed bushings.
Here's a picture...
Now...the Z axis. I'd prefer not reinventing the wheel, so to say. The X-Y unit was almost predesigned...is there is single axis sliding vise? Some elegant way to make a bolt on Z axis? I could do another X-Y vise, mounted vertically, and just not use one of the axes...but that seems silly.
Anyone have a simple, elegant, and reasonably easy to build Z axis design? I'm wondering if a $5 machinist's vise from Harbor Freight would be sufficiently precise...bolt a router mount to the movable jaw, and just bolt it onto a vertical support.
Obvoiusly the leadscrew would have to be replaced for decent function, but this might work, if there's no lateral play. Surely there's a better, though still cheaply priced alternative to this approach.
I'm trying to do this on the ultra-cheap...basically, to see if it can be done...with off the shelf parts. I could do the window channel routine, and I even have some of it, but I'm not sure that would provide as much rigidity as even a cheap cast iron vise...proably better precision, though. I'm trying to stay away from the "buy some 5 inch long THK rails on eBay" routine, though, since it's not repeatable.
Comments? Suggestions? All are welcome! Help me make this project a success...
-- Chuck Knight