Ok, first a little background. I am in college, always get started on projects over breaks, then they fade out over the semester. Anyway, a couple years back, I bought some random linear bearings and some odd assemblies on ebay and threw them together on a wooden frame just to get some satisfaction of a 'cnc machine'. It's been sitting in my basement collecting dust ever since.....

So, this winter, I got hooked on the idea again that I am going to make a mill that might actually be able to do some work.

Goals:
1) Design a small machine that can mill some small aluminum parts.
2) Use what I have previously purchased, but let a little money out so I can actually build a decent machine.
3) Try to keep cost low.


Well, goal 3 is going to be an issue, since I'm already over $500 and don't even have a frame built (or a head assembly), but it could be worse. I've sold some things to offset the cost, anyway.

In the spirit of keeping things cheap, I'm using SBR16 supported shaft rails for the X/Y table motion.
For the Z, I had 17" long 5/8 thomson shaft with 2 precision steel bearings. I cut the shaft in half, bought two more bearings and 4 pillow blocks to press the bearings into. Not sure if this is going to be too small of travel yet.... I think I can only squeeze 2.5 to maybe 3" of travel out of it (thinking off the top of my head without the shafts in front of me).

I scored a pair of 18" big ballscrews with timing pulleys on the end off ebay for a good price, and they seem in great condition, so I will use them for the X and Y table motion.

Here is the current lot of parts, with the Y axis semi-assembled on 1/4" 8x18" aluminum plate. The 'saddle' plate is just a 1/4" 6x8" plate right now. I will probably beef up that saddle, just trying to decide if I need different dimensions. The X will be similar, except only 6" wide if I keep the current plan. This should allow a decent work area table for small stuff.



You can see the screw and 6x18" plate on the right. On the far left, you can kindof see a small ballscrew assembly that I might use for the Z axis, the only problem I have is that it is, I think, 1 TPI, and I am not planning on using $200 stepper motors.

I have received the second set of linear shaft bearings, so I will just set it together later and take a pic for you to see what my plans are. Currently I just want everything together so I can see how this will work out.

I'm having trouble designing a frame though. Really can't decide which approach to take. I was inspired by Leeway's 8020 build. Steel tubing (possibly filled with something) may be a cheaper option though. I'd like to stay away from having things welded though...
I was also looking at the possibility of purchasing the 'solid column' replacement from LMS to use, and possibly the mini mill head assembly to bastardize and try to put a makeshift belt-drive on until I could make brackets. I'd like some thoughts/suggestions on spindle and column ideas if you have any.

Anyway, more to come...