Morning,
I can get hold of largish sheets of this craftfoam modelling foam cheap:
https://www.panelsystems.co.uk/product/styrofoam-ravatherm-xps
It has a feel to me that it could be used to make a board - is it a daft idea? Seems quite strong. What else does it need?
https://i.postimg.cc/TwjgSmHg/IMG-3641.jpg
https://i.postimg.cc/RFxwXGGv/IMG-3642.jpg
It can work but not a so good idea because of poor resin adhesion on Xps.
Aah, that’s interesting. Too solid of a surface on the XPS?
It has potential.
XPS can work with the proper density (pcf; kg/l), suitable mininimum compressive strength and good pre-glassing, foam surface preparation.
What foam densities are available?
See these links.
https://www.swaylocks.com/comment/568957#comment-568957
https://www.swaylocks.com/comment/569355#comment-569355
I used some for full boards or rails bend. Repaired many score that were made with it, near always peeling of skin problems…
But diy plane builder use it and they fly with so it work for them! Seems they used a specific one’s called spider foam…
I’ve made at least a dozen XPS surfboards, heat is a problem, and adhesion to the foam is a problem. I’ve had several delam in the last 2 years, causing large bubbles. If you leave tiny pin holes in the glassing, it shouldn’t get air bubbles. As far as how the board feels in the water, XPS is somewhere between EPS and PU. XPS foam shapes easily and you can get a very nice finish, but leave it course.
I added this image of an older XPS I made then stripped to make another board. Even with the foam roughed up using a 60 grit sanding block, the glass peeled off so easily and clean. I used the stripped off glass for templates.
Wow, that’s impressive! Hard to imagine that it would come off so cleanly. Almost makes me think you would need to run a spiked roller over it all to make lots of holes before glassing!
I could only get 3" thick XPS and I shaped about 4 from a single sheet of 8’ x 24" x 3" XPS. On one of the boards I added a bit of nose rocker with this brick after I laminated the bottom. I really liked that board, but I don’t use it much now. A friend shot me riding it in 2015
"Bondage Boutique Stainless Steel Wartenberg Pinwheel - Lovehoney
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Apparently, neurologists and/or their patients found an alternate use.
Much cheaper than an aircraft porcupine roller.
Great minds think alike!
But the main thing is - does it help?
Of course it help to give a better bond. That and a strong stiff lam and no more problems with xps…
Wallpaper Perforator
same same
$17 on fleabay
Critical factors for XPS perforation are:
Pin diameter
Number of pin rows per inch
Number of pins per wheel/row.
Roller diameter and pin length
The more small diameter holes the roller makes per square inch, the better.
The 7-row Wartenberg rollers (22 pins/wheel) I have make 44 perforations per square inch. Pinwheel diameter, pin-tip to pin-tip, is 1.125" (28.6 mm). Roller width is 1" (25.4 mm), pin-tip to pin-tip. Pin length is approx. 5-6 mm. Perforation hole diameter at the foam surface is approx. 1 mm. Space between perforation holes is approx. 4-5 mm.
At the Boardroom Show a few years ago I met the German guy behind the Hydroflex Glassing Technique.
He had taken a board he’d built and cut it into slices only about ¼" thick.
You could** not** peel the glass away from the foam. Super Strong.
https://www.kjadesigns.com/hydroflex/
Do you end up spiking the entire surface?
This thread shows a XPS repair. The original glass peeled pretty easily. For the repair I manually stabbed a lot of holes. No delam yet, but no sun or hot cars.
https://www.swaylocks.com/forum/109927/tx-points-snapped-xps-repair-stringer-rebuild-and-weights
I’m building a board skinned with aerolite, a HD foam used by boat builders and will similarly deface it with holes.
Bufo (hydroflex) théorie was same, anchoring resin in blank like tree roots so lam stay stabilized by foam while it bend so it’s not buckle so easily. That’s how board break. They used stringerless blanks, came from windsurf world, initially they work with xps then move to pu and finally to eps. Worked well but not drastically better than other’s.
Everything that reduce skin buckling improve durability…
