Hey Chris,
I originally wanted to roll up the wire on a drum as you stated with a
simple DC motor. I was going to devise a simple mechanical switch that as
the tension decreased it would actuate the motor. Instead I have run the
wire through a pulley system similar to what you would see on an exercise
machine. The length of the wire will only fluctuate 7 to 10 inches at the
extremes of travel. The wire is attached to either an extension spring or
maybe a piece of surgical tubing(I won't know until I troubleshoot the
machine). The tubing will allow me to play with the length in relation to
tension a bit easier than an extension spring would. I do not need as much
tension as on a feathercut because the wire will not be under extreme load
(ie at setup ready to go, weights hanging on a feathercut system). I will
be able to play with the cut speeds to minimize wire sag (I hope). As I
said before, if it does not work I can always use the bow.
Thanks for the thought,
Marc Webster
>From: "Chris Kaiser" <[EMAIL PROTECTED]>
>To: "Marc Webster" <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]>
>CC: <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]>
>Subject: RE: [RCSE] C.N.C.
>Date: Tue, 13 Mar 2001 11:00:13 +1300
>
>From: Marc Webster [mailto:[EMAIL PROTECTED]]
> >
> > Hey Pat,
> >
> > I have been working on a design for a CNC foamcutter for the past few
> > months.
>...
> > have also attemted to eliminate the need for the cutting bow (hope it
> > works). Instead as the wire changes length with wing tapor and z
>height,
> > the wire is payed out and retracted as needed. If this does not work, I
> > have still made provisions for a bow.
>
>I presume you're calculating the required wire length and driving
>a stepper to change the length? Wouldn't it be simpler to maintain
>a constant tension in the wire? This could be done by terminating
>the wire on a drum driven directly by a DC motor. The motor would
>operate stalled most of the time, with it's stall torque (and hence
>wire tension) controlled by the applied voltage.
>
>Just a thought.
>
>Ciao - Chris
>
>******
>Chris Kaiser
>Auckland, NEW ZEALAND
>http://rcmodels.co.nz/clubs/asfcnz
>
>
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