Something i have been wanting to do for a long time, ever since I saw an instructable on home CNC was build one just for fun. Well the price of most of the materials makes it no so fun. The pipes for the first one, would have come to 40-50$ at the local Ace hardware, so i concentrated on electronics. The board i was building in a recent post was a controller from the instructable.
I tried with drawer slides and I could never get the table square enough to do anything serious. Everything was always binding and the cheap steppers I picked up on eBay were just not strong enough to move the table without dropping pulses. The idea was still simmered in the back of my mind...
Then I ran across the Mantis 9.1. It had two secret ingredients that made it all come together. The rods/bearings idea, and the sacrificial table idea. The Rod/Bearing and match drilling made everything square up, and the bearings made everything easy to move with weak motors.
The flatness of the table was guaranteed by simply using the machine to mill the table flat relative to the spindle.
I guess the best thing about the design, was that it could be built cheap. He used 1/2" Plywood, and he evidently used a Shop Bot to cut out the basic parts. Looking over the design i kept seeing Reference line sand to here. I realized if I got a 3/4" MDF shelf it had three edges that were as square as I needed. I invested $5 on the shelf, and printed out the plans and just spray tacked them to the shelf and took after the it with a jig saw.
Couple of caveats - MDF makes a lot of dust - keep a shop vac handy and wear a mask. MDF uses up tools in a hurry. About half way through cutting the basic pieces, the cutting was slowing to a crawl. When I examined the jigsaw blade the teeth were completely worn down to nubs.
I got a cheap set of blades and kept it up. Later I realized the table saw had a blade with carbide cutting teeth, and it made short work of the rest of the square pieces.
Being the cheap person I am, :-), I wasn't about to order hardened steel bars cut to length from McMasters. I found a more than serviceable replacement in the metals bin at the local hardware store, and at Lowes. The 3/8" plated rod 36" long costs a whooping $3.69 and two is all I needed. Easily cut to length with a hack saw. The bearings cost 1.69 in brass, and 2.69 each in bronze (from two different stores).
So the initial investment in the Hardware came to all of 33$ so far. I wish the first store had more of the cheaper bearings.
The drive screw I am planning on using is standard 1/4" x 20 x 12" threaded rod I had. You have to pick over the stock to get one straight enough without nicks. I got a long nut used to join the rods and just threaded it over the selection and found one that the nut moved smoothly over the full length length.
I dry fit all the parts and took a picture. The wife took one look at it and said, "I thought it would be bigger" This mill has always been the prototype - and I don't really plan on using it for more that a try out. Refine the build, taking into account lessons learned make one for real. I'll have to make the next one bigger though - for her ;-)
Next will be finishing up the parts, mounting the electronics and trying it out. Stay tuned - film in a few weeks,
