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Introducing the Hoff - a transparent acrylic board

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rynhardt
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Re: Introducing the Hoff - a transparent acrylic board

Postby rynhardt » Mon Jan 26, 2015 10:19 pm

The beam mould released without any drama :D and then it was the usual wax-on and wax-off a few times to prep the surface, and then some PVA release agent.

I also got a piece of 5mm clear perspex with which to close off the mould - the idea being that I'd be able to keep an eye on what's happening inside.

The cool thing of having this mould is I can use it to create a foam core, and then I can wrap the core in fibre and stick it back into the same mould to get a perfect surface finish. :thumb:

To create the core I went shopping and after handling a few samples decided on a polyurethane foam that expands up to 8 times by volume - this had the right amount of rigidity without being too heavy.

This is a two part foam that you mix 1:1, and then you have around 2 minutes to get it into the mould before it starts expanding.

I drilled a 16mm hole in the middle of perspex to serve as a pouring opening, and then clamped the sheet to the mould. Then I mixed up a batch of the PU foam and started the pour..

Only, the foam was expanding faster than I could pour it and eventually filled the mould only partially. :o

The solution: put the seperate parts in the fridge prior to mixing and you can extend the pouring time to about 4 minutes, which turned out to be enough time to get the mix into the mould and evenly distributed before it started expanding.

The end result is a very nicely formed core that just needs the edges trimmed a bit. Total weight is 103g.

Next I'll be wrapping the core in two layers of 200gsm glass. At around 0.14sqm per layer I expect the laminate to add a further 50g-80g.
Attachments
mould with perspex cover.JPG
Mould with perspex cover and PU foam inside.
core with mould.JPG
Finished core with the mould.
PU core before trimming.JPG
Finished PU core still needs the edges trimmed. The red is the PVA release agent that will be washed off with water.

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Geronimo79
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Re: Introducing the Hoff - a transparent acrylic board

Postby Geronimo79 » Mon Jan 26, 2015 11:08 pm

Cant wait to see a video of you riding that board. Really curious how it looks.

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rynhardt
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Re: Introducing the Hoff - a transparent acrylic board

Postby rynhardt » Sun Feb 01, 2015 8:32 pm

Further progress.. to test the concept I did a trial run with some glass fabric. The final product will use carbon.

I prepped the mould and then pre-impregnated some 400g biax glass, which was then cut to size.

Wrapped the foam core with the wet glass, stuck this into the mould and clamped it into place with a piece of 5mm perspex.

Waited 24 hours for the initial cure and then stuck it onto a hot box at 50 deg C for a 16 hour post-cure.

Released the finished beam, trimmed off the excess epoxy and voila! A finished product with a nice polished surface, no sanding or hot coat required. :thumb:

The photo doesn't do it justice but I'm really happy with the end result. :D
Attachments
pre-impregnated glass.JPG
pre-preg glass cut to size
into the oven.JPG
place mould and beam into the hot box.
post-cure.JPG
post cure at 50 deg C
finished beam.JPG
finished beam

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rynhardt
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Re: Introducing the Hoff - a transparent acrylic board

Postby rynhardt » Thu Feb 12, 2015 4:13 pm

The end is in sight..

I took the first carbon beam out of the mould yesterday, after the post-cure cycle completed.

It looks awesome. :thumb: I just need to trim the edges.

Layup was 245gsm carbon twill (0/90 deg), 150g carbon triax (+45/-45/180 deg), 300gsm carbon uni-directional (0 deg).
Attachments
carbon beam released.JPG

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rynhardt
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Re: Introducing the Hoff - a transparent acrylic board

Postby rynhardt » Sun Mar 08, 2015 7:40 pm

It's done! :D

Two carbon fibre beams, glued to a sheet of 5mm polycarbonate, with some bindings bolted on.

It's done! And it only took a year. :o

From concept to reality.. Nothing beats that feeling of bringing an idea to life! :thumb:
Attachments
finished.png
quad_render.png

BWD
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Re: Introducing the Hoff - a transparent acrylic board

Postby BWD » Sun Mar 08, 2015 11:46 pm

Cool! What are the dims and weight?
Look forward to more info and ride report!

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rynhardt
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Location: Johannesburg, South Africa

Re: Introducing the Hoff - a transparent acrylic board

Postby rynhardt » Mon Mar 09, 2015 8:33 am

Board specs:
  • length: 140cm
    width (middle): 47cm
    width (tips): 37cm
    rocker (per side): 5cm
    weight: 4.2 kg (board only)
It does actually float :)
Attachments
hbs4.png
hbs5.png
hbs3.png

User avatar
rynhardt
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Posts: 556
Joined: Wed Sep 11, 2013 3:51 pm
Kiting since: 2010
Local Beach: Leeupan
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Style: Freeride
Gear: GK vSonic 6 & 11
Cloud C2 17
Progeni Mutare
Xelerator door
Hoff DD140
Brand Affiliation: None
Location: Johannesburg, South Africa

Re: Introducing the Hoff - a transparent acrylic board

Postby rynhardt » Mon Mar 09, 2015 8:55 am

First wet run yesterday at the cable park. The board performed well and nothing broke :thumb:

Thanks to my buddy Dave for some excellent work behind the lens!
Attachments
hb9.png
hb5.png
hb3.png

longwhitecloud
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Re: Introducing the Hoff - a transparent acrylic board

Postby longwhitecloud » Mon Mar 09, 2015 9:28 am

epic! get fish spotting

BWD
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Re: Introducing the Hoff - a transparent acrylic board

Postby BWD » Mon Mar 09, 2015 1:48 pm

:thumb:


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