photographing carbon fiber is extremely difficult...

photographing carbon fiber is extremely difficult...

sniper1rfa
sniper1rfa

October 30th, 2011, 5:56 pm #1

especially with winter afternoon sunlight when the clouds are patchy and racing across the sky...

This is a test mule for a carbon/glass longboard. Laminated over an old board I planed thin so the composite was doing most of the work. This is a precursor to a foam core version.

18oz. carbon on top, 18 oz uni glass and 12oz biax on the bottom. Carbon on top makes sure the glass gets loaded, glass on the bottom ensures a nice powerful flex.













Have done some testing with foam core stuff, and this construction shows promise for the lovely light weight of CF/glass without the excessive stiffness of pure CF. Some experimental presses have come out really well, though we overdid it on the glass - 36oz unidirectional made for the right flex when pressed in some shapes, but too stiff when pressed in others. The foamcore tests were 1/4" foam and a wheelbase around 50".

This is all done with wet layups and a vacuum bag.
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NZGene
NZGene

October 30th, 2011, 11:01 pm #2

How dit you manage the sharp transition with the laminate on the top rail curve? Very nicely done. The stringers on that base of that deck will also make it much stiffer and doing deck relief or stringer like that takes a few tries to work/feel right with composites.

Foam does require a little extra care especially around the thru-holes and in the rail. Are you planning on laminating to the edge or casting /capping the foam edge. I've had a lot of success casting, either clear or tinted epoxy rails using slow cure epoxies.

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sniper1rfa
sniper1rfa

October 31st, 2011, 12:26 am #3

we've come to the conclusion that foam isn't an appropriate core material for this app.

By the time the board is flexible enough to have nice pop the foam is suffering excessive shear and failing, leaving you with a suddenly limp board. Thinking about trying balsa with the grain going across the deck (for torsional rigidity) or possibly an aramid honeycomb.

As far as edge capping - we'll be lasering the core material, so we can laser it undersize and then laser a sort of stencil that the core presses into. That way all the edges have a nice wide, durable cap. It also allows us to support the truck mounting positions with the stencil, and just core out the non-critical areas.

The lamination is done with an oversize blank, and the finished product can be routed, lasered, or water-jetted to the final dimensions. That way I can get a nice sharp edge and I don't have to worry about poor wet-out at the extremities.



This one is actually an old board I had built and broken a while ago. I planed it down super-thin and then added those ash stringers to bring it about halfway to full strength. Laminated way over the edge and re-routed the excess off. Hand finished it with sandpaper. I have a pattern I use with the router - this is the sixth variation of this board.




I'm mostly doing this to learn more about building structural composite parts. It's been interesting so far. Amazing how much effect the core has on the properties of the finished piece.s
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OmniMech
OmniMech

October 31st, 2011, 4:12 am #4

especially with winter afternoon sunlight when the clouds are patchy and racing across the sky...

This is a test mule for a carbon/glass longboard. Laminated over an old board I planed thin so the composite was doing most of the work. This is a precursor to a foam core version.

18oz. carbon on top, 18 oz uni glass and 12oz biax on the bottom. Carbon on top makes sure the glass gets loaded, glass on the bottom ensures a nice powerful flex.













Have done some testing with foam core stuff, and this construction shows promise for the lovely light weight of CF/glass without the excessive stiffness of pure CF. Some experimental presses have come out really well, though we overdid it on the glass - 36oz unidirectional made for the right flex when pressed in some shapes, but too stiff when pressed in others. The foamcore tests were 1/4" foam and a wheelbase around 50".

This is all done with wet layups and a vacuum bag.
What other stuff could you do that pattern on?
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NZGene
NZGene

October 31st, 2011, 6:48 am #5

we've come to the conclusion that foam isn't an appropriate core material for this app.

By the time the board is flexible enough to have nice pop the foam is suffering excessive shear and failing, leaving you with a suddenly limp board. Thinking about trying balsa with the grain going across the deck (for torsional rigidity) or possibly an aramid honeycomb.

As far as edge capping - we'll be lasering the core material, so we can laser it undersize and then laser a sort of stencil that the core presses into. That way all the edges have a nice wide, durable cap. It also allows us to support the truck mounting positions with the stencil, and just core out the non-critical areas.

The lamination is done with an oversize blank, and the finished product can be routed, lasered, or water-jetted to the final dimensions. That way I can get a nice sharp edge and I don't have to worry about poor wet-out at the extremities.



This one is actually an old board I had built and broken a while ago. I planed it down super-thin and then added those ash stringers to bring it about halfway to full strength. Laminated way over the edge and re-routed the excess off. Hand finished it with sandpaper. I have a pattern I use with the router - this is the sixth variation of this board.




I'm mostly doing this to learn more about building structural composite parts. It's been interesting so far. Amazing how much effect the core has on the properties of the finished piece.s
Aah off course, edge trimmed and clearcoated/flowcoated.

What density and type of foam core have you tried so far? Ive had great success with 100-120kg PVC foam or even the cheaper nycell(PVC signboard foam) but it is still expensive compared to a good maple or cedar and now where near as nice flex.

Balsa sheet(not endgrain) is light but not that great either. It also easily fails in shear, especially in thinner cores. Been using poplar and paulownia(Japanese call it Kiri) with great success. Makes very nice wood core boards, much lighter than maple or cedar and still very responsive. Im dying to try bamboo but have not found a commercially consolidated sheet that did not weigh a ton or require hydraulic press to mold.
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NZGene
NZGene

October 31st, 2011, 6:50 am #6

What other stuff could you do that pattern on?
... and pretty much any shape. That's the beauty of it.
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FireFrenzy
FireFrenzy

October 31st, 2011, 9:08 am #7

especially with winter afternoon sunlight when the clouds are patchy and racing across the sky...

This is a test mule for a carbon/glass longboard. Laminated over an old board I planed thin so the composite was doing most of the work. This is a precursor to a foam core version.

18oz. carbon on top, 18 oz uni glass and 12oz biax on the bottom. Carbon on top makes sure the glass gets loaded, glass on the bottom ensures a nice powerful flex.













Have done some testing with foam core stuff, and this construction shows promise for the lovely light weight of CF/glass without the excessive stiffness of pure CF. Some experimental presses have come out really well, though we overdid it on the glass - 36oz unidirectional made for the right flex when pressed in some shapes, but too stiff when pressed in others. The foamcore tests were 1/4" foam and a wheelbase around 50".

This is all done with wet layups and a vacuum bag.
If you will excuse the slightly "popular" linguistics...

Looking good bro;)
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sniper1rfa
sniper1rfa

October 31st, 2011, 11:35 am #8

What other stuff could you do that pattern on?
as long as epoxy will stick to it, or it can just be made straight up from CF.

The stuff is super strong and extremely flexible. We made a section of just flat carbon fiber, about 1/32" thick and 1' wide - you could fold it over and stand on it and it would hold you up like a spring. The thicker the laminate, the stiffer it gets. If you do a half inch foam core it's ridiculously rigid and light, and even with one layer top and bottom it's damn near impossible to break without power tools. The strength is also directional, so you can play with the fiber alignment and change the properties of your part drastically.


Really incredible stuff. When it comes to that, plywood and fiberglass are also incredible for the same reasons.
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sniper1rfa
sniper1rfa

October 31st, 2011, 11:37 am #9

Aah off course, edge trimmed and clearcoated/flowcoated.

What density and type of foam core have you tried so far? Ive had great success with 100-120kg PVC foam or even the cheaper nycell(PVC signboard foam) but it is still expensive compared to a good maple or cedar and now where near as nice flex.

Balsa sheet(not endgrain) is light but not that great either. It also easily fails in shear, especially in thinner cores. Been using poplar and paulownia(Japanese call it Kiri) with great success. Makes very nice wood core boards, much lighter than maple or cedar and still very responsive. Im dying to try bamboo but have not found a commercially consolidated sheet that did not weigh a ton or require hydraulic press to mold.
bad answer, i know...


Trouble is this thing will see deflections of 2" sometimes, maybe more, over a section 3/8" thick and 45" long. It's a lot of bending - I think by the time the foam is flexible enough to do that it won't be useful as a core anymore.
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upriver
upriver

October 31st, 2011, 3:58 pm #10

we've come to the conclusion that foam isn't an appropriate core material for this app.

By the time the board is flexible enough to have nice pop the foam is suffering excessive shear and failing, leaving you with a suddenly limp board. Thinking about trying balsa with the grain going across the deck (for torsional rigidity) or possibly an aramid honeycomb.

As far as edge capping - we'll be lasering the core material, so we can laser it undersize and then laser a sort of stencil that the core presses into. That way all the edges have a nice wide, durable cap. It also allows us to support the truck mounting positions with the stencil, and just core out the non-critical areas.

The lamination is done with an oversize blank, and the finished product can be routed, lasered, or water-jetted to the final dimensions. That way I can get a nice sharp edge and I don't have to worry about poor wet-out at the extremities.



This one is actually an old board I had built and broken a while ago. I planed it down super-thin and then added those ash stringers to bring it about halfway to full strength. Laminated way over the edge and re-routed the excess off. Hand finished it with sandpaper. I have a pattern I use with the router - this is the sixth variation of this board.




I'm mostly doing this to learn more about building structural composite parts. It's been interesting so far. Amazing how much effect the core has on the properties of the finished piece.s
If you want any real data I have an entire materials test lab (and the knowledge of how to use it) at my disposal. I recently finished up a bunch of testing on two inch thick end grained balsa cored composite panels. By end grained i mean that if you peal the composite skins off you are looking at the growth rings. I think someone already mentioned this but the shear resistance of balsawood is not that great.
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