About to start building a CNC wood router

Well, I knew joining this group would pay off. The recent thread about
optically isolating the parallel port, I feel, will be most helpful in
my building a CNC wood router for my own workshop. Especially since I'm
homebuilding my own board. what can I say? I'm a nerd!

Anyway...like the subject line says, I am about to start building the
machine itself. And, I'm trying to do it on the cheap, while
maintaining some level of precision. Unlike metalworking setups, I
don't require a level of precision measured out to 10 decimal
places...the wood will move more than that with changes in humidity! A
few thousandths of an inch would be nice, though. My intention is to
build wooden (laminated material) clock parts, so reasonable precision
is going to be a priority.

Here's my problem. I live out in a small country town...our primary
sources of parts are WalMart, a small local hardware store, and some car
parts stores. Thankfully I'm a nerd and had some old HP LASER printers
that I could scavenge some steppers from -- 100 oz in. Not huge, but
they should be sufficient for a woodworking lathe, and they're of very
good quality.

And, thankfully, I've been inspired by John Kleinbauer's (sp?) plans for
a hardware store CNC mill. That means things like rollerblade bearings
on iron pipe for the linear bearings. This I can manage, with our
meager selection of parts. This is the design I'm blatantly
copying...it should give me a sufficiently large working area, and it
looks buildable with parts and materials I have available. Hopefully it
gives you sufficient detail for comments, and suggestions. It's a
moving gantry/fixed table design.

http://www.cnczone.com/attachment.php?s=&postid=2427

As usual, the Devil is in the details. So I have a question about the
lead screw and the anti-backlash nut. The only threaded rod I can get
in this town is allthread, which is 60 degree standard screw thread.
Not the best for transferring loads. Is this going to cause me trouble
in the future? I mean, I know it'll work, but will it work well enough,
and for a sufficiently long time? Should I just bite the bullet and
mail order some acme threaded rod? Where can you get it? My background
is not in machining, so I don't know the parts sources!

And, the anti-backlash nut. Obviously nothing like this is going to be
available in my little town...I've heard tale of people homebuilding
them from anything including wood, plastic cutting boards, and even
tapped brass. How is this done? Simply tapping "some" material should
not provide greater precision than a storebought nut...or would it?

I appreciate any help or insight you can provide...

-- Chuck Knight