Re: [CAD_CAM_EDM_DRO] About to start building a CNC wood router

On Thu, 08 May 2003 23:37:14 -0500, you wrote:

>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!

<grin>

>
>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.

And the size of this project is?

>
>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.

www.herbach.com for herbach and rademan, good quality steppers, but
low in-oz, little bigger than 100 oz/in, but not bigger than 200 right
now.

look for electronics goldmine on the web, L298 drivers with heatsink
for 2 dollars each. Go look at the specs, you will probably want the
L297 controller chip as well, Mouser electronics www.mouser.com has
them. For the board, if you can do printed circuit boards, you will
be *very* happy. www.mgchemicals.com has a good PC board kit, most of
this you can breadboard yourself. I'd recommend the most dense
negative you can get, period. Inkjet may work fine. Go through the
archives of the homebuilt pcboards group if you want, there's some
good stuff there.

also for some things, like the z axis, you may want to go to linear
bearings. www.mcmaster.com you can get 1/2 inch ceramic bearings
(need to be lubricated, but tolerate dust a bit better than linear
ball bearings) for under 10 dollars each. I'd recommend getting the
precision shafting as well, simply because it is hardened and will
match.

>
>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.

The roller blade bearings are metric, and need an 8 mm rod. That is
also available from McMaster Carr. I found a source of 8 mm reamers
(unless you have a drill) at Wholesale Tools www.wttool.com. However,
I'd prefer reamers myself.

>
>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.

Ick...

Acme Rod is surprisingly inexpensive. Enco has a sale on it, IIRC....
www.use-enco.com. Available in 3 and 6 foot lengths, but you're
likely to pay a bit more for shipping if you get the 6 foot length.
Nuts are more expensive than not, but the inexpensive plain variety
can be turned down. (Hint: turn it down on the shaft to make it
centered),

> 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!

You don't have a lathe? Access to one? Drill press I hope....

>
>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?

Might, but an Acme thread is an expensive tap.

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

Some of this is possibly OT for this list, so please contact me
directly if you need more information. All these places do ship by
UPS, and even in a major metropolitan area, you'd be surprised about
what you can't find, and how expensive it is otherwise.

Harvey

>
> -- Chuck Knight
>