[coherent]

I (and I bet others) would be interested in hearing of ideas or experiences for keeping costs down and accuracy/size up. I think most of us are aware of the skate bearings, drawer slides and aluminum window channel possibilities, but what else? Here's a few that worked for me to start the thread off.
-Marc

I'm a ebay watcher and some pretty good deals can be found there if you watch. I'd love to build a $20k cnc router setup, but it's just not in my "hobby" budget (just ask my wife). Here's a couple of low cost alternatives that worked for me:

1. My very first machine used some small diameter steel shafting I scrounged from old printers and oil impregnated bronze bushings which I found at a local bearing supply dealer (about $1 each). If you're not using really small/low torque steppers, they'll do a good job and make for a fairly tight slide unit. You need a good polished shaft for these, or the friction/drag is too high.

2. I got 8 small used NB linear slides and rails for $25 on ebay. The rails were very short (4-6in each or so) and no one was bidding. I priced the rail and it was over 20 cents per mm, or over $5.00 per inch. Enough for one 48" axis would have set me back nearly $500. Ouch... so I bought a piece of uhmw, cut 2 48" strips a little wider than the short steel rail that came with the slides. I ran them through a surface planer making very small adjustments until it was exactly the right width. I then cut a grove down each side with a small ball mill cutter using a router table to match the original rail grove. Now I'm not saying I have the precision that stainless steel rails have, but they are very tight and smooth and I'm using the 2 48" "uhmw" linear rails on my current machine. They work great, and mounted on a flat solid surface support a 36" moving gantry. Total cost was less than $25 for the axis including the small ball mill bit!

3. My lastest find was 13 brand new 1in ID linear bearings (the round kind). You can often get these fairly cheap without the pillow block holders or shafts/supports. I paid $40 for all of them as a "buy it now". I found a metal/steel place and ordered enough 1" turned, ground and polished shafting, (two 4ft, and two 3ft pieces) for a very nice x & y axis for under $60. The shaft is spec'd at +0 to -.0005 which is great for cnc router purposes. Fashion a few shaft mounts and bearing holders out of some scrounged uhmw or aluminum, and you have a pretty accurate and solid x & y setup for a little over $100.

How about you? Any good ideas for Hobby lead screws? Couplers? Slides? Cabling, Cable tracks? Bearing mounts? Details? Pictures? Fess up, inquiring minds want to know!