>I've hot wired spider foam several times with no problems. Tonight I
>just ruined 3 wing cores...
>...like a perfect cut. When I inspected the core, it had 1/8 inch ripples
>all over the core. Looked like a perfect sine wave. The second core I...
I have had the "ripple" or "washboard" surface problem when cutting high
density foams. Observing the current draw on the meter of my regulated
supply showed the problem to be lack of available amperes to heat the wire.
The power supply just ran out of guts. The ripples have NOTHING to do with
wire speed. When I increased the amps available the problem went away under
all cutting speeds and conditions. (I solved the problem by running the
supply at 12 VDC and then connecting my winch battery in series with the
current regulated supply so that it still regulated the wire heat with
changes in core lengths and cutting speeds.)
My experience with both Spyder foam, and the Dow HiLoad-60 foam (which I
sell to modelers as SkyCore) is as follows:
A substancial amp draw occurs as the wire gets deep in the foam. The
density being nearly twice that of "ordinary" blue foam and nearly three
times that of bead foam, heat is rapidly drawn out of the wire by the
melting foam. If your power supply cannot keep up with the demand for
amperes DURING the "in motion" portion of the cut, that's probably why
you're getting the washboard surface (an expensive problem with HD foams, I
realize). An ideal cutting speed is when the cut surface is covered with
very fine "angel hair" of melted foam filaments. Slower than that leaves a
slightly shiny, pitted surface. Any faster results in too much lag at the
center of the wire. Super smooth and polished templates help to avoid cut
speed fluctuations too.
Dan deVries
DEVRIES DESIGN, Inc.
Product Design --+-- Patent/Litigation Graphics
_______
_____________ |_______________
0
[EMAIL PROTECTED]
Dan deVries
290 - 68th St. SW
Grand Rapids, MI 49548
Office: 616-281-2271
Fax: 616-281-2294
RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to [EMAIL PROTECTED]
