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Green Foam

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Istvan Travnik:
Visiting the factory datasheet, this is absolute close relative of the blue and pink foams.
(as you measured, its density fits to the lower third of extruded polystyrene foams. )
About complete technology, covering, etc. materials, see:
"The bluefoam model, or how to..."  topic here.
I described the most usual traps/failures working with XPS foams.
Istvan

Brent Williams:
Spent the afternoon cutting some foam stabs using this Kingspan GreenGuard foam.  It took a much higher wire temperature vs Dow foam. 
Produced several nice stab sets for vacuum bag experimentation.
8" root, 6" tip, 13" panel width. 
Each panel of the stab weigh in at 13g for the Dow grey 25psi XPS foam and 18g for the Kingspan GreenGuard.
So, that is not a deal breaker weight, but it is something to consider.

Istvan Travnik:

--- Quote from: Brent Williams on February 25, 2024, 10:29:02 PM ---Spent the afternoon cutting some foam stabs using this Kingspan GreenGuard foam.  It took a much higher wire temperature vs Dow foam. 
Produced several nice stab sets for vacuum bag experimentation.
8" root, 6" tip, 13" panel width. 
Each panel of the stab weigh in at 13g for the Dow grey 25psi XPS foam and 18g for the Kingspan GreenGuard.
So, that is not a deal breaker weight, but it is something to consider.

--- End quote ---
Dear Brent,
Magnifying your photos, it looks to be cut at too high temperature, regarding the pretty big waves on the surface.
I suggest to adjust the minimal current on the laboratory supply unit*, which is enough to cut very slowly the foam. Be patient!
 And longitudinal, "sawing" movements** are a "must" to get waveless surface.

*no precise result can be obtained without it
**yes, the surface will be hairy, but smooth, without grooves and ridges... Hairs can be easily "harvested" from surface with well known tricks/procedures. My friends in our club built computerized cutting rig, and I observed the basic differences between manual, "sawing", and the digitally feed techiques. Manual technique melts the foam by transferring the heat by contact between the string and the foam, and "sawing" is needed to enlighten the feed, resulting "hairs" in 20 or 30° direction. The gap is absolutely equal as string's diameter, not bigger.
Computerized rig naturally cannot do "sawing". It needs significantly higher temperature, and the melting heat's transfer is by RADIATING, not by contact. Will not pull "hairs", hurray!! But...
... the melted channel/gap is some 1-2 millimeters big, and the surface -however isn't hairy- not smooth enough, it is some printed picture of melting "appetite" of actual spot. It can be sanded to smooth (even with wet paper), but the surface is far from the original path, unlike the "sawed" one.

Istvan

Brent Williams:
The grey foam was the first run of the series and we were still fiddling with the wire temp and feed rate.  The green foam tests turned out very smooth as we found a wire temp that worked well.
Also, as Ken mentioned, the green foam does sand quite nicely for hand shaping. 

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