I've sent a PM to cbcnc requesting some info about the his machine he posted in the gallery. In the mean-time however I have a question that I hope you guys can answer.

What kind of bearings are these show in the picture?

Are they oil-impregnated bronze bushings?

by the way.... here is a link to his gallery for some more pics of his machine.

http://www.cnczone.com/gallery/showgallery.php/cat/500/ppuser/240

They certainly appear to be bronze bushings riding on drill rod or possibly hardened, precision ground rod. Very robust looking.

Is friction much of a concern when using bronze bearings?

I'm looking for a bearing solution for my CNC Router I'm planning. I am attempting to use a set of 100oz Steppers from HP Laserjet III printers.

Of course I'm also under a budget so I'm mainly looking for the biggest bang for my buck. I was tossing a few ideas around using rollerblade bearings but the use of them seems to greatly complicate the designs.
http://www.cnczone.com/gallery/data/500/2588cnc_assembly.jpg

http://www.cnczone.com/gallery/data/500/2588cnc_assembly1.jpg

Nice design mvaughn! If I remember correctly the friction of a oil impregnated bronze bearing decreases as the shaft's radial RPMs go up due to the oil being drawn out of the bearing's surface. I think this would apply to an axial load also. You may want to explore the polymer bearing by Igus, they make an all polymer replacement for the bronze sleeve and thrust bearings. Looks very cool to me and not too expensive, about $5. And they work better on CRS shaft then on a very smooth surface.

Mark,

They are Oilite Bronze Bushings with a flange. They are riding on 3/4" cold rolled steel shafts. I turned some 1 1/4" od Al tubing to 1"id and pressed the bearings in to make the holders. They seem slick enough. I had more problems lining up the shafting so it wouldn't bind. I am using 80 oz Vextas and 1/2"-10 Acme to drive the axes.
They were obtained from McMaster Carr. Do a search for Bronze bushings. They were really inexpensive at about $1.00 each.
I can't take credit for the idea as Paul (CNCAdmin) posted some pics of his machine and started me thinking.
I haven't forgotten about you and posting the details.

Chris