Hi Ollie: I experienced similar teething problems when I started foam
cutting. I resolved almost all the ripple effects by making the bow as light
as possible, making sure the templates were as smooth as possible, and
maintaining a tight and clean wire. I have a bow with a spring loaded, self
tensioning feature with results in smooth, clean cuts with crisp trailing
edges. Rich.
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From: Oliver Wilson [SMTP:[EMAIL PROTECTED]]
Sent: Wednesday, November 17, 1999 7:16 AM
To: Dave Wenzlick
Cc: [EMAIL PROTECTED]
Subject: Re: [RCSE] Need help on spider foam
>When this happened to me it was because I was cutting a large core
and using .011
>wire. What was occuring was the cutting wire was actually rotating
very
>slightly back
>and forth as it went through the core. The melting foam would tug
unevenly on the
>wire and rotate it a little one way then it would rotate back the
other.
How could you tell the wire was rotating? Was this a direct
observation or
an inference?
If uneven drag on the wire was causing rotation, what might have
been
causing uneven drag on the wire? Could it have been bowing of the
foam
because of internal stress relief? Could it have been caused by wire
drag on
the templates? If it was caused by internal stress relief, a
solution might
be to hold the foam blank in place with pressure applied through a
foam pad
so that the foam behind the cut is bent into contact rather than
allowing an
open kerf and a small ammount of uncontrolled foam movement.
The end
>result was a core with very small ripples as you describe. The
ripples were worse
>towards the center of the core which would be another clue that
this might be
>happenning. I switched to the normal stainless steel fishing leader
wire and the
>problem was solved.
I use 0.02 monel metal fishing leader wire under about 50 pounds of
tension
and have cut several dozen spyder foam cores mannualy without
experiencing
the ripple problem.
This also happened when I was cutting up a large block
>of foam to
>make some core blanks. I was dropping a 52" bow through some foam
with too thin a
>wire in use. Same weird ripples appeared. Again, using thicker wire
solved
>it. I have
>not had this problem on less than 36" bows. On those I continue to
use the
>.011 wire.
>
>Good luck,
>
>Dave Wenzlick
Regards, Ollie
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