re:RE:Bearing Material

James,

You've gotten a lot of good advice already. Here's my $.02

First thought, Acetal(delrin) Easy to machine. Hard enough. Slick
enough.(use a lube, dry or wet) See note on the alum. guide, tho!

nylon "moves" a lot so it will not hold the precision you may need.
Same for the UHMW (high density polyethylene). The way around this
limitation is to use VERY thin sections backed up with a "non-moving"
housing.

Pacific bearing applies this principle in their bearing line, which
is something to look into. Also used by the makers of
the "gorolite??" product mentioned. (Recognised the decription, but
not the trade name)This is good stuff, but Hi-dollar as it comes from
an aerospace supplier.

Personally, I'd reconsider the aluminum guide. Fairly precise steel
is available (as drill rod, or ground tool steel) at good prices from
local machine shop suppliers, or mail order. Since your proposed
machine is small, the length restrictions imposed will not be a
problem.


Below is maybe not for this project, but fits in this thread:

I'm gonna go ahead and throw some wood on the fire. Use WOOD! Oil-
impregnated MAPLE blocks were commonly used as bearings early in the
century. Drill a hole(for round rod guides). Cut a slot(to adjust
clearance). And keep the dimensions/design aware of the direction of
the likely movement(wood expands in width, but not much in length).
Also the endgrain is what you want to use for the "bearing" surface.

Stand/soak the blocks on their end in some machine oil until nature
does its thing and the blocks are oil filled, then mount them to the
machine. Use baltic birch ply (or 5 ply maple "die block") for even
better results! Yes list, I have done this! It works! I wouldn't
use it on a bridgeport retro, but for a routing/engraving machine,
it's ok!

Hope this helps.

Ballendo (who just lost his credibility :-) )