David,
I don't have ideas, as such, but a pointer to a current project from which
you might get a few.
Your machine has been admired from afar, over on one of the Parallax fora,
from an active thread of documenting a project to build a PCB mill (link to
top of thread:
http://forums.parallax.com/forums/default.aspx?f=15&m=76791&ord=d).
The current mechanical research is using some sort of screw with
anti-backlash nuts, extruded Aluminum strut, along with some form of
recirculating ball slides.
Daniel
> -----Original Message-----
> From: Homebrew_PCBs@yahoogroups.com
> [mailto:Homebrew_PCBs@yahoogroups.com]On Behalf Of David McNab
> Sent: Wednesday, 20 July 2005 06:32
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Junk E-Mail [Homebrew_PCBs] need ideas - linear bearings for
> cnc
>
>
> Hi,
>
> It doesn't need to be said that the makeshift linear bearing and
> transport I've been using with my CNC setup
> (http://www.freenet.org.nz/cnc) is less than ideal.
>
> The mill is working ok for drilling, with all holes landing within
> acceptable proximity to targets.
>
> However, for artwork drawing, the inadequacies start to stick out like
> the proverbial canine body parts.
>
> I've taken on board people's earlier suggestions to use aluminium on
> high-density plastic, but am concerned this will only improve the
> situation slightly.
>
> As the current CNC setup goes, the software is pretty well finished, and
> is performing well with managing drilling and artwork drawing runs,
> using data in exported Eagle files.
>
> But with the hardware, there's way too much play, x y and rotational.
>
> The threaded rod works by pulling/pushing on a thread which
> I tapped into the sides of the platforms, which are 3mm thick
> aluminium.
>
> I could reduce much of the X-Y play by welding nuts onto the
> platform sides, unless someone has a better (non-specialised)
> idea.
>
> But to really address the problem, I'll be needing to totally change to
> a proper linear bearing system, which needs to get as close as possible
> to my target of < 100 microns play.
>
> I've seen a few commercial linear bearing products, but these would cost
> more than the other parts in the drill put together.
>
> Can anyone please suggest a simple, accurate linear bearing solution
> which can be resourced and put together without specialised parts, and
> with minimal wallet injury?
>
> All suggestions appreciated.
>
> --
> Cheers
> David
>
>
>
> Be sure to visit the group home and check for new Links, Files,
> and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
>
>
>
>
>
>