Hi everyone,
lots of people here seem to be touring skiers (right words ?...) but not many if us tell about the weight of their skis.
A bunch of friens and I have (re-)started the project of skibuilding and we're all touring skiers; thus the ski weight is a (very) non negligeable parameter, and so the choice of materials.
I'd like to know if some of you have weighted their skis, and what materials did you try (FG, carbon, kevlar-carbon ?) and also for the core (type of wood and thickness ?)
Last year we did a pretty fat and short ski ( viewtopic.php?t=842 ), and each weighted 1.6 kilogram. Not too bad but we used pretty expensive materials (carbon and kevlar carbon) and a core mixed of fir and ash.
I thought about that, because I am trying to build an Excel file with the caracteristics of all the skibuilders skis (http://www.skibuilders.com/gallery/) and apparently theses/you guys only use 22oz trix FG, one layer over and upper the core.
what materials do you use ? What's your recipe ? What is the weight you reached ?
many thanks.
ski weight
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Re: ski weight
good point! i`m also interested in making lighter skis.
my evil twins (177cm lenght, 152-125-138) were built with a horizontal ash core, 0.9mm thick veneer, 11mm core. one sheet unidirectional carbon 140g/m2, 2sheets of biaxial 308g/m2 and some carbon bands and partial reinforcements - 2250g per ski.
the latest ones, the cockaynes (182cm, 152-132-142) i built with a vertical fir core mixed with some ash veneer. 13mm core thickness - the core mainly consists of fir, 11mm. this fir part of the core could be used withouth the ash veneer for a ski and just the core weighted about 680g - really really light i think. on theses skis i used 2layers of biaxial 308g/m2 and 2 layers of 220g/m unidirectional fibres. - 2200g per ski.
i don`t know if fir is the best wood for cores - maybe poplar would be a little better...
maybe you can reduce the weight a little by using carbon, but the feeling i`ve got is that carbon is bad in terms of vibrations.
furthermore, if you use wood the weight of a ski is maybe 80% given because i think you have to place special reinforcements under the binding if you`re using a light woodcore. the same with honeycomb - maybe you can gain a few grams, but it`s a lot of work and your skis won`t be "bombproof"
my evil twins (177cm lenght, 152-125-138) were built with a horizontal ash core, 0.9mm thick veneer, 11mm core. one sheet unidirectional carbon 140g/m2, 2sheets of biaxial 308g/m2 and some carbon bands and partial reinforcements - 2250g per ski.
the latest ones, the cockaynes (182cm, 152-132-142) i built with a vertical fir core mixed with some ash veneer. 13mm core thickness - the core mainly consists of fir, 11mm. this fir part of the core could be used withouth the ash veneer for a ski and just the core weighted about 680g - really really light i think. on theses skis i used 2layers of biaxial 308g/m2 and 2 layers of 220g/m unidirectional fibres. - 2200g per ski.
i don`t know if fir is the best wood for cores - maybe poplar would be a little better...
maybe you can reduce the weight a little by using carbon, but the feeling i`ve got is that carbon is bad in terms of vibrations.
furthermore, if you use wood the weight of a ski is maybe 80% given because i think you have to place special reinforcements under the binding if you`re using a light woodcore. the same with honeycomb - maybe you can gain a few grams, but it`s a lot of work and your skis won`t be "bombproof"
plywood freeride industries - go ply, ride wood!
Re: ski weight
Here is a link to Bambi's ski flex program which I revised to add two features:alexisg1 wrote:ski weight is a (very) non negligeable parameter, and so the choice of materials
A weight calculator so that you could estimate the materials in the ski
A revision to the layers and materials so that you could investigate different types of material and different orientations of each cloth layer
Here is the URL for the revised spreadsheet:
http://eyemarine.com/skidimmsexeREV1.xls
Only edit the cells coloured yellow
I am also very interested in weight so I am targeting building a ski in the 1.6kg weight, my last pair of carbon/glass skis were 1.9kg but they are so stiff that you would need to weight 200kg to turn them!!
@plywood: whaow, I'm impressed of the relative light weight of the cockayne, considering that they are mega-FAT skis ! I am wondering why you used veneer as you made them "white" in the end ? Do you think using veneer add some interesting characteristics ti the ski ? end thus might replace some other layer ?
thanks tnoyt for the link. I'd seen it before but I thought it might be too much complicated ;-)
another question : plywood says he/she uses (for the cockayne) 2layers of biaxial 308g/m2 and 2 layers of 220g/m unidirectional fibres. Is it also a way to make skis lighter comapred to the triax 744 g/m² from skibuilders ? Or does the epoxy, on the contrary, make this solution heavier ?...
thanks tnoyt for the link. I'd seen it before but I thought it might be too much complicated ;-)
another question : plywood says he/she uses (for the cockayne) 2layers of biaxial 308g/m2 and 2 layers of 220g/m unidirectional fibres. Is it also a way to make skis lighter comapred to the triax 744 g/m² from skibuilders ? Or does the epoxy, on the contrary, make this solution heavier ?...
This are my lightest ones.
110-80-99 mm, length 178 cm, weight: 1.1Kg (per ski). Super soft flex, 10mm camber.
Ash woodcore (by Ludovic Lacroix) 3 mm thick at tip and 11 mm thick in the center.
Reinforcement: bottom layer: carbon UD 200g/m2 and biax (38.5°) 250 g/m2; top layer: carbon biax (45°) 250g/m2 only at tip and tail.
They are extremely soft, so the pressure on the edges at the tips is low; nevertheless, they are nice to ski on piste, after I got used. Off piste they are good, and super light for touring. By adding some carbon (less than 100g in toal) on top layer would increase the stiffness.
One consideration on weight: in a standard ski, the weights are distributed like this:
wood core (ash) 900g
base and edges 300g
glass (750g/m2) 250g
resin 200g
A balsa or Airex core would weight less than 250g, while carbon (triaxial 250g/m2) would be 90g, so only 150g can be saved when replacing carbon with glass.
The best way to go light, is to make the core lighter, rather than using heavy cores and carbon fiber.
110-80-99 mm, length 178 cm, weight: 1.1Kg (per ski). Super soft flex, 10mm camber.
Ash woodcore (by Ludovic Lacroix) 3 mm thick at tip and 11 mm thick in the center.
Reinforcement: bottom layer: carbon UD 200g/m2 and biax (38.5°) 250 g/m2; top layer: carbon biax (45°) 250g/m2 only at tip and tail.
They are extremely soft, so the pressure on the edges at the tips is low; nevertheless, they are nice to ski on piste, after I got used. Off piste they are good, and super light for touring. By adding some carbon (less than 100g in toal) on top layer would increase the stiffness.
One consideration on weight: in a standard ski, the weights are distributed like this:
wood core (ash) 900g
base and edges 300g
glass (750g/m2) 250g
resin 200g
A balsa or Airex core would weight less than 250g, while carbon (triaxial 250g/m2) would be 90g, so only 150g can be saved when replacing carbon with glass.
The best way to go light, is to make the core lighter, rather than using heavy cores and carbon fiber.