The Hoff WW140 - wave twintip

[rynhardt]

Would get the core down to 7mm maximum , if you are less than 60 kilos better 6mm thickness going down to 2mm in the tips. What density does the corecell have ??
You have a great rockerline, will be an interesting twintip.
http://www.nomadkiteboarding.com/

I'm 85kg in my birthday suit, so I thought 10mm with carbon would be a good starting point, going down to 5mm in the tips.
I'll probably use the M80, see table below.

Experimenting is so much fun!

PS. Nice carving pic! Makes we want to get this thing done and see how she rides!

[plummet]

I agree with board dude. Get the core down to 8mm max taper out at the tips 2-3mm. If you roll with 300gm db carbon 10mm to 5mm core at tips will be WAY to stiff!.....

[rynhardt]

I agree with board dude. Get the core down to 8mm max taper out at the tips 2-3mm. If you roll with 300gm db carbon 10mm to 5mm core at tips will be WAY to stiff!.....

Well I'm kinda committed to 10mm/5mm unless I do a bunch of extra work. Maybe go with glass instead of carbon then?

[rynhardt]

Got my ABS pieces back today. Feels like christmas

The 5mm ABS sheet 1000x660 was USD 12.00
The waterjet cutting was USD 38.00

So got my rails and stringer sorted for USD 25 per board.
I have a little bit of solvent welding to do this weekend to make it homogenous, but ABS is nice to work with in that respect.

And once this is done, it will also form the template for the foam cutting.

[downunder]

Dude, this is one over engineered board One thing tho, if using a CNC it's not DIY any more

Kidding, use whatever floats your boat. The water cutting would cost me at least $150, abs >$100, etc. Can't afford any of this...

[board dude]

Looks great, the abs work is first class, very clean and professional,
Looks like you are using some 3d software, we use the Rhino software ,all my cnc work is on 3DM files, if you need anything let me know.
I am using 6,7mm thickness for standard 80 kilo rider weight boards, the more flex the better the board will work , you should be in the 2 to 1mm thickness in the tips, the more flexible it is the less chance it will break. Have confidence in well laminated carbon, its mega strong. I am using 100d Airex core, the pink stuff, same as F1 and the Americas cup boats.

Have a look at this stress test - basically no load in the tips. Direction of travel is too the left.

[rynhardt]

Looks great, the abs work is first class, very clean and professional,
Looks like you are using some 3d software, we use the Rhino software ,all my cnc work is on 3DM files, if you need anything let me know.
I am using 6,7mm thickness for standard 80 kilo rider weight boards, the more flex the better the board will work , you should be in the 2 to 1mm thickness in the tips, the more flexible it is the less chance it will break. Have confidence in well laminated carbon, its mega strong. I am using 100d Airex core, the pink stuff, same as F1 and the Americas cup boats.

Have a look at this stress test - basically no load in the tips. Direction of travel is too the left.

Yeah the outfit that does the cutting did a great job at a good price. A compelling option to have.

I get by with Blender, cannot afford Rhino or Solidworks, and would love some built in FEA capability. But for now feedback from the forum is filling that gap, thanks everyone!

What's your thoughts on keeping to 10mm centre, 5mm tips, but using glass instead of carbon?
Carbon's modulus is approx 3 times that of Eglass, so 3 times stiffer for the same thickness.
And bending stiffness increases with the square of the thickness, if I recall correctly?
So I reckon for the same weight and layup, the core thickness needs to be sqrt(3) more for glass. (1.73x)

That stress diagram is magic.. where have you been hiding that all this time?

[board dude]

What's your thoughts on keeping to 10mm centre, 5mm tips, but using glass instead of carbon?
Carbon's modulus is approx 3 times that of Eglass, so 3 times stiffer for the same thickness.
And bending stiffness increases with the square of the thickness, if I recall correctly?
So I reckon for the same weight and layup, the core thickness needs to be sqrt(3) more for glass. (1.73x)

Thanks we get a very good idea with computer programs how kiteboards work , but nothing replaces loads of test boards.

You should be okay with 10mm and a fibre lamination , its a shame though not to pursue that carbon beauty.
A quick idea would be to use a flat router of 16mm diameter set to 3mm and take a shave off the entire finished core, very precise and relatively easy. You would need to make 25 passes to work a 400mm wide board , a good days work for Sunday afternoon.

Keep an eye on my core thickness which is controlled by the large concave , the concave controls about 25% of the boards flex.

Pictures of a 146 showing concave before finishing. PS , I like the foam core argument on the other side of the Forum. I can think of at least 10 different chemical foam cores, most of them not suitable for kiteboards, might be more interesting if the foam core used is specified and its density, would give the forum a better idea of what is working.

http://www.nomadkiteboarding.com/index.html

[rynhardt]

You should be okay with 10mm and a fibre lamination , its a shame though not to pursue that carbon beauty.
A quick idea would be to use a flat router of 16mm diameter set to 3mm and take a shave off the entire finished core, very precise and relatively easy. You would need to make 25 passes to work a 400mm wide board , a good days work for Sunday afternoon.

Keep an eye on my core thickness which is controlled by the large concave , the concave controls about 25% of the boards flex.

Pictures of a 146 showing concave before finishing. PS , I like the foam core argument on the other side of the Forum. I can think of at least 10 different chemical foam cores, most of them not suitable for kiteboards, might be more interesting if the foam core used is specified and its density, would give the forum a better idea of what is working.

I'm too lazy to cut down the core. I'd rather get 3mm ABS next time round.

Corecell is a SAN based foam, which is supposed to have the best properties of X-PVC and Linear PVC (airex), especially in terms of impact resistance.

Those boards look real tasty, and they have a fair amount of concave on them. Very nice.
I assume the concave flattens out at the tips to enable them to be more flexible?

[board dude]

Corecell is a SAN based foam, which is supposed to have the best properties of X-PVC and Linear PVC (airex), especially in terms of impact resistance.

Corecell looks great, send me an email if you need more info, the Airex might be interesting for you.
Check out the picture of the f1 car, the hoop around the driver is made of the same pink Airex we use to build our hybrid cores. Have a look at our youtube channel and you can see videos of the same pink cores being machined.
Most F1 teams use this pvc type in aero components , floor pans etc.
Its critical that the pvc suffers no de-lamination, great impact absorption/distribution properties.

I assume the concave flattens out at the tips to enable them to be more flexible?

Back to kitesurfing and the wave-twintip uses a tunnel concave , to say the concave is the same all the way to the tips, it needs it for stability, we always design and test to make the boards mega easy to use.

Congratulations again on your abs rails, looking forward to see more pictures.

Quick video of Sergio doing his thing. https://www.youtube.com/watch?v=T6NcQR2TH4k