Re: has anyone built a 4x8 CNC router?

I now have a hobby router that I built. It is 24"x10" I swore
that I would never build another one after building that one. But,
after some thought, I have figured out ways of overcoming the
problems that discouraged m (shaft alignment, using different
bearings, using a small motor instead of a dremel tool) I think for
now I am just going to build a 2'x2' router by reusing alot of the
same parts from the hobby router. Is there any disadvantages to
using supported shafts as opposed to linear guides?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, JanRwl@A... wrote:
> In a message dated 8/8/2004 2:25:54 AM Central Standard Time,
> mjmautoinnovations@y... writes:
> Has anyone built a 4x8 CNC router?<<
> I did a 5x10. NEVER again! TOO Much work, and NOT enough money!
There are
> "store-bought" X-Y machines that size for less than MY cost for
materials and
> parts, NOT including my "labor"!
> I am hoping to build one cheaply.<<
> This would be akin to building a new luxury automobile at home for
$5000.
> I have a pretty good idea if what I want to do. But, I am unsure
about a few
> aspects. For example leasdscrew sizes, stepper sizes" &". <<
> Only 4x8? "Professional rapid-traverse rates", or slow as a box-
turtle? It
> MAKES a difference! If you use preloaded ball-screws, one with
at least
> 1.3" major dia. would be needed for the 8' axis, if not 1.5
inches. To turn
> that and move a gantry of the size/weight I'd expect you would be
doing, you
> would need a good Size-42 stepper with "chopper drive". For
the "Y-screw", I'd
> STILL use at least 1.3" dia. A triple-stack bipolar "KML-093-
nnnn" stepper by
> Superior Electric would possibly do if your machining is fine, and
you use
> proper bearings, well-aligned. For the longer X-axis, that goes
without saying!
> Do NOT expect to support "the motor-end" of the screw by the
> motor-shaft/bearing! Use DUAL "fixed" angular-contact bearings at
both ends of BOTH screws,
> and a proper "no slop" (aka "no backlash") coupling connecting one
end of the
> screw to the resp. motor.
>
> Take it from me: When you go to the Stepper and Driver store,
take MONEY!
>
> If you think you can do this with ACME screws and preloaded
Turcite bearings,
> one or both of TWO things will come to your attention: You may
need LARGER
> motors (to overcome the friction) than you expected, and/or your
SPEED of
> traverse will be reduced.
>
> Sounds all negative and nasty, doesn't it? Lotsa luck. HOPE you
can prove
> me wrong. Been nearly two decades, now, since I had finally
discovered what it
> means to say, "Been there; DONE that!"
>
> Jan Rowland
>
>
> [Non-text portions of this message have been removed]