I have good experience when constructing cores like yours in using two ash stringers running from tip to tail and place them where the binding screws go. Center and outside of the stringers is paulownia or fir. The short sidewall under the bindings is ash again.
For the taper I use a circular arc that is tangent to the narrow part of the core and ends in 45 degree angle to the sidecut. I would make the taper even gentler (larger arc radius), which also helps draping the fibres and topsheet in that area.
HB (Hansen Boards)
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
Thanks for the share. I had a similar break in a full paulownia core, (snowboard). Right between two reinforced areas. Strangely I have another board with the same lay-up but with veneer, and the veneer has prevented the topside from buckling. So maybe I would not only feather out your binding area reinforcements but also extend veneer a bit further and make the taper more gradual. (I mean don't have the tapered core as abrupt or right next to the rigid binding plate)
Bottom line though, a full Paulownia core asks a lot from the composite not to buckle in a deep bend. It just crushes fairly easily. I've thought about maybe a 2mm inlay of hardwood but will probably just stack more unidirectional composite with long tapers in the risk areas.
It's wild how the fracture in the carbon cloth runs up and down on the 45 axis as it crosses the ski. Oh I see, that is black basalt. If you can find it, Try a thin layer of Textreme over the Basalt and you get a real smooth finish without pinholes, looks really cool in the sunlight too.
Bottom line though, a full Paulownia core asks a lot from the composite not to buckle in a deep bend. It just crushes fairly easily. I've thought about maybe a 2mm inlay of hardwood but will probably just stack more unidirectional composite with long tapers in the risk areas.
It's wild how the fracture in the carbon cloth runs up and down on the 45 axis as it crosses the ski. Oh I see, that is black basalt. If you can find it, Try a thin layer of Textreme over the Basalt and you get a real smooth finish without pinholes, looks really cool in the sunlight too.
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SleepingAwake
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No, and that was my downfall.pmg wrote:Hi, they still look nice! Did you use the dovel method to keep the core in place?
I decided to try without, as that was where the last pair broke. I realize now that I could have easily aligned my cores using blocks glued to my press as these skis have sidewalls in the middle.
I'll chalk it up to learning and make sure it doesn't happen again.
I am nobody. Nobody's perfect, so I must be perfect.
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SleepingAwake
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Another pair of skis finished..
This is an everyday on piste cruiser.
It is my first ski with a full sidewall. Normally I did a cap.
Also I stained an ash veneer green and airbrushed the graphics onto that
Then used a 2 component Matt clearcoat over that..
Ash core 1.5 - 12 - 1.5
600 Triax & Carbon stringer layup top and bottom.
Fiberglass weave under foot.
Result is very stiff.
But for on piste blasting that should be OK
This is an everyday on piste cruiser.
It is my first ski with a full sidewall. Normally I did a cap.
Also I stained an ash veneer green and airbrushed the graphics onto that
Then used a 2 component Matt clearcoat over that..
Ash core 1.5 - 12 - 1.5
600 Triax & Carbon stringer layup top and bottom.
Fiberglass weave under foot.
Result is very stiff.
But for on piste blasting that should be OK
I am nobody. Nobody's perfect, so I must be perfect.
Yes, the core goes right to the tip about 3mm short.burnside wrote:Such thin tips! Excited to hear how these ride.
Does you core extend all the way to the tip and tail?
I changed to cap construction on the tip as I didn't want the core exposed where it was cut through the fibres of the wood. On the sides the grain runs parallel to the cut so it should remain relatively waterproof. On the end grain the wood would not be so water resistant, therefore I don't expose it there.
I am nobody. Nobody's perfect, so I must be perfect.
Here is a video of the skis in use.
They are fantastic to ski on.
Stable smooth and easy to turn.
https://www.youtube.com/watch?v=5Bn3rw8pTik
They are fantastic to ski on.
Stable smooth and easy to turn.
https://www.youtube.com/watch?v=5Bn3rw8pTik
I am nobody. Nobody's perfect, so I must be perfect.
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skidesmond
- Posts: 2338
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- Location: Western Mass, USA
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