BOARD DESIGN AND LOTS OF OTHER TECHNICAL STUFF
(if you dig deep enough)

The board design evolved through discussions with various riders
and drawings done on scraps of paper.
The major contributors to the shape were
Chris Bainbridge, Dave Hackston and Lewis Wilby.
Deck construction
Jim Cambello provided advice on combining GF with Carbon.
Advanced Composite Group provided much help with layup advice & correct materials.

Below are some of the more legible sketches:

(click on pics for enlargement)

Chris Bainbridge's  idea for carbon binding mount

Lewis's original concept design with integrated trucks.

Dave Hackston's boned design

Chris Bainbridge's  original  Manticor shape 2005

LB03 Based on a Jum Cambello Design of GF & Carbon

LB03 being tested at Brancaster by Lewis Wilby 2006
Photo provided by Peter Archer

DECK CONSTRUCTION

The construction of CKB decks has evolved over a period of 4 years.
The first land deck LB01 was constructed in the same manner as the
kitesurf boards I made. This made a very light deck of 800 grams as it
used a sandwich construction of carbon prepreg skins on a 10mm core
of Herex High temperature structural foam.
(The higher spec temperature version of Airex).
The high temperature version was needed to allow the resin to be cured
under pressure at 120 C.

The thickness gave a very stiff but brittle deck and was tested to destruction by
several riders simultaneously jumping up and down on it.

Under some guidelines from Jim Cambello I made all subsequent 30 odd decks
( apart from a few concept decks), from solid carbon or carbon and glass.

Basic Method:
Carbon Prepreg is an Epoxy resin  infused  into the fibres of woven or non-woven
carbon fibre in a gel like state.
The resin remains in a semi set condition until raised to a certain temperature.
There are various resin types which I use:
LTM Low temperature cure > 65 C
MTM Medium temperature Cure 120 C
HTM High Temperature Cure > 120
VTM Variable Temperature Cure. 65- 130 C
The chemistry of prepreg resin is quite complex as various things are added to
help with UV resistance and to give toughness to the higher spec versions.
The ratio of resin to fibre Vf % is often specified as the Volume fraction which
is dependant on whether the curing process is done at very high pressure in an
autoclave or lower pressures in a vacuum bag.
Generally more resin is required at lower pressures as the resin diffuses less easily
into the voids. Resin films can be added to boost resin content and co-cure with
the lay-up.

The reinforcement fibre is either carbon or glass.
This can come in various forms also:
BD=Bi Directional, UD=Uni Direction and Triax = Tri Axial
The individual fibres are bunched together into tows.
So a 12K tow has 12 thousand individual fibres.

Prepregs are made into various thickness which gives the GSM ( Grams per square metre)
or weight of the material. This can vary between 150 gsm to 700 gsm.

Generally the thinner materials are used for surface finish.
Different grades of carbon  give variations in cost to  strength and modulus (flex) ratios.

Strength of carbon composite  is also mainly due to the direction that the tows lies in relation to the force
applied so for a composite thickness of typically 6-7mm several layers ( up to 30) have to be laid up
on each other arranged in various orientations to provide the right amount of stiffness and strength.

To create a product in carbon prepreg, a tool has to be constructed as a mold
to hold the carbon prepreg together whilst it cures.
I construct my landboard and skateboard tools from 5mm Aluminium sheet formed into
the desired shape. The finished surface can be polished and coated in a release agent or
covered in a thin PTFE sheet reinforced with glass fibre. Best results have been obtained
using the PTFE sheet as this allows trapped vapours to bleed out.

To calculate the number of layers I use a spreadsheet into which formulae relating GSM,
Vf%, Resin & Carbon Density can be entered. The results give final cured thickness and
weight value which can then be used to calculate flex for a given width.

I lay down each layer of prepreg  onto the tool   making sure non of the plastic backing
is left behind. After several layers have been pressed down the assembly is sealed in
a re-useable elastomer vacuum bag (RVB). Vacuum is applied to consolidate the layers
and remove any trapped air. This is done several times as the thickness builds up.

Finally the completed lay-up has a caul plate applied to the upper surface which is a thinner
aluminium plate shaped to the upper surface and covered in PTFE. The whole assembly
is wrapped in release film held together with flash tape. ( Nylon sticky back tape).
This is  placed inside the RVB with a thick breather fabric either side which helps vacuum
consolidation.
The RVB is sealed and vacuum applied  via a breach valve to give 15 psi pressure.
A vacuum drop test is performed using a vacuum gauge to check for leaks.
The RVB is placed in a thermostat controled oven and the temperature ramped up slowly
through a pre defined rate to 120 C. This is held for 1-2 hours depending on the resin type..

After a slow cool down the vacuum is removed and the bag un-sealed.
The deck is released from the tool easily using a plastic card and finally given a rough trim.

A flex test is carried out on the deck which can then be entered into a spreadsheet .
This allows calculation of the final width to give the correct flex.

Boards with thickened spine

Click HERE for slide show and description of oven construction & complete lay-up & cure.
Click HERE for slide show and description of drilling procedures
Click HERE for pics and Video of shaping and cutting