Re: [CAD_CAM_EDM_DRO] Re: Back to the rack - nuts to the nuts

vrsculptor wrote:

>
> --- In CAD_CAM_EDM_DRO@y..., "ballendo" <ballendo@y...> wrote:
> > But there is a steel tape based encoder I saw awhile aback that
> > wasn't too expensive, and had very good accuracy. (NOT the UK "tape
> > measure" one(s).)
> >
> Ballendo, Doug,
> I agree with your aproach but not your solution. The anorad metal
> tape is $12/inch, $650/read head. I was asking a while back about
> using a cable/capstan with a USDigital.com encoder on a large router.
> Feed back from the group was that there were problems with slipage
> and cable diameter. I haven't investigated any further but this still
> seems the way to go. For less than $12/inch I should be able to get
> precision cable and you should be able to design out slipage.

See my image posting of January 8/2002 :
http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/cali.gif

I think a better way would be to anchor the cable end at HOME,
and run the cable to an encoder on the router head, which is
tensioned by the wire continuing on across the room to a pulley
on the ceiling, terminating with a weight. A little math is
involved regarding the wire (coming off the pulley at different
angles depending on the height of the router head), but this
should work (if not for leadscrew compensation, then at least
for software compensation to ensure you can trace a square
with perfect 90 degree corners and equal side lengths - rather
than getting a diamond trapezoid depending how far you are off).

Doug Fortune
http://www.cncKITS.com



















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