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Re: Pocket foilboard divynicell 80 core Ghetto build tips?

Posted: Sun Sep 15, 2019 9:15 am
by rynhardt
+1 Bohme! Nice design!

Re: Pocket foilboard divynicell 80 core Ghetto build tips?

Posted: Sun Sep 15, 2019 10:35 am
by merl
Brilliant. But strictly speaking it is not a ghetto build if you have vacuum :)

Re: Pocket foilboard divynicell 80 core Ghetto build tips?

Posted: Sun Sep 15, 2019 3:14 pm
by bohme
omg wrote:
Sun Sep 15, 2019 7:32 am
Bohme, that*s an awesome board. What material is the stringer? And is the board stiff?
The core of the stringer is also PVC, just a bit thicker. I used longitudinal UD carbon tape both on the stringer and on deck for stiffness.
The thickness of the stringer is matching the KF box against the deck laminate.
The board is stiff enough for a wave foil (90kg), but I guess you would prefer a stiffer board for a racefoil.

BTW, look at the photo from my workshop. My wife calls it a Ghetto...

Re: Pocket foilboard divynicell 80 core Ghetto build tips?

Posted: Wed Oct 02, 2019 9:51 pm
by merl
faklord wrote:
Tue Sep 10, 2019 6:31 pm
merl wrote:
Tue Sep 10, 2019 4:40 pm
Back to the original topic, a high density foam ghetto build (no rocker table or vacuum). Two questions:

1 Would it be possible to bend 25mm thick 75gm2 PVC foam using a heat gun?

https://www.easycomposites.co.uk/#!/cor ... -core.html
1) Yes I have done this with the exact material you linked to. It ended up a bit brown but no obvious effects to mechanical properties (didn’t go powdery or brittle). I only did this on a scrap piece to see if it worked. Didn’t go on to make a board with it. But it is what I’ll do if I make another board.
I bought some of the above foam. Really hard and thick stuff so pretty difficult to imagine exactly how it will bend with heat. Can you give some idea of how to bend it? I assume you used a heat gun. Do you need to heat both sides? How long before the bend is set? Thanks again for the tips.

Re: Pocket foilboard divynicell 80 core Ghetto build tips?

Posted: Wed Oct 02, 2019 10:55 pm
by BWD
Bends above 170 F.
If you make a jig/rocker table, an easy way to bend this foam to it is using hot water.
Boil a big pot of water and put a couple of towels in it.
Put a hot, wet towel on the jig, then your core, then another towel on top. Pout some more hot water on top. Sand bags etc can be used to bend the core to shape. Or you could build a two part mold/jig. It can sometimes be easier to build a jig to the deck rocker than the bottom rocker. Many ways to skin a cat. Don’t burn yourself.

Re: Pocket foilboard divynicell 80 core Ghetto build tips?

Posted: Thu Oct 03, 2019 3:10 am
by Bille
*

Re: Pocket foilboard divynicell 80 core Ghetto build tips?

Posted: Thu Oct 03, 2019 8:49 am
by faklord
merl wrote:
Wed Oct 02, 2019 9:51 pm
faklord wrote:
Tue Sep 10, 2019 6:31 pm
merl wrote:
Tue Sep 10, 2019 4:40 pm
Back to the original topic, a high density foam ghetto build (no rocker table or vacuum). Two questions:

1 Would it be possible to bend 25mm thick 75gm2 PVC foam using a heat gun?

https://www.easycomposites.co.uk/#!/cor ... -core.html
1) Yes I have done this with the exact material you linked to. It ended up a bit brown but no obvious effects to mechanical properties (didn’t go powdery or brittle). I only did this on a scrap piece to see if it worked. Didn’t go on to make a board with it. But it is what I’ll do if I make another board.
I bought some of the above foam. Really hard and thick stuff so pretty difficult to imagine exactly how it will bend with heat. Can you give some idea of how to bend it? I assume you used a heat gun. Do you need to heat both sides? How long before the bend is set? Thanks again for the tips.
I just clamped a piece in a workbench. Heated both sides with a heat gun, simultaneously applying pressure to the free end.
If BWD’s boiling water trick works, I’d give this a go. In fact I might give this a try just out of interest.
One option might be to use steam (eg from a wallpaper stripper), possibly even making a steam box to localise the heating to a controlled area for a few minutes.
For a foil board, I wouldn’t bother with a rocker table as the I don’t think the exact rocker shape is that important. You just need to bend the front up a bit (~10cm?)

The bend was set soon after the heat was removed. No jig required - just held the free end for a few 10s of seconds.
Best thing to do is try it out on a scrap.

Re: Pocket foilboard divynicell 80 core Ghetto build tips?

Posted: Thu Oct 31, 2019 10:42 pm
by TomW
merl wrote:
Sun Sep 15, 2019 10:35 am
Brilliant. But strictly speaking it is not a ghetto build if you have vacuum :)
Ok, let's have some fun.

What are the rules for a ghetto build!?

1. No vacuum
2. Build it outside or unheated shed. A bit unfair to peeps in cold climate... Building in your kitchen, living room, bedroom or bathroom might be considered ghetto?
3. No power tools