number two!

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plywood
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Joined: Fri Oct 13, 2006 2:13 am
Location: wilen, switzerland
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number two!

Post by plywood »

as i contacted davide to get some base and edges of him for my first skibuilding project, i ordered stuff for 2 pairs of ski. just in case something went wrong, i had material for a second one ;)

but, as you may know, my first ski was a success and i honestly would not know what to improve on these skis, even if i had to. well, at least at the moment after 2 days of riding :D maybe time will show me some opportunities.

so i still had material for one ski laying around. because of this i decided to build a second one. even though i`m a student and have more freetime than others, i can`t ride 3 pairs of ski and 2 snowboards. and that`s the reason why i want to build a ski for my girlfriend.

well, it also has some egoistic reasons: first of all she has a season-pass for a local resort and is riding there 2days nearly every weekend. so she could use them often. secondly, until 1,2 years ago, she was in an alpine racing team. so she can ski and maybe could give me some differentiated feedback about the skis. all in all it would be kind of an acid test for my skis :D

but now for the hard facts:

at the moment she`s riding a rossignol scratch with 173cm. as she told me it`s a bit too long for her, a too wide radius and too narrow for being confortable for longer excursions in the powder.
so first of all i sized the scratch: 173cm long, 108-78-101, running lenght 147cm (nearly as long as the one on my own ride!), tip is 14cm long and 44mm high, tail 12cm long and also 44mm high.

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then i reflected how to change the geometry to fit her wishes.

out came a ski with 164 overall lengt, 136cm effective edge, a 15cm long tip with 55mm of height (as on the "swallow") and a 12,5cm long tail which is about 50mm high - because she likes to ride switch time by time. then i increased the sidecut and out came 132-98-122. this should also be enough for powder.

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here the cut out bases. i`m thinking about doing some die-cut grafics again, but i`m not sure up to now...

because of the shorter running lenght and the thighter radius of the tail i had to shorten my mold. this was done by putting a block of hard foam into it. i cut it with a bandsaw, but it would also be possible to cut it with a hot wire. then i covered it with 2 layers of 1mm birch plywood to distribute the forces. and it hold up to 1,5bar. so maybe this would also be a cheap alternative for building a mold. a sheet of this foam costs 35CHF and it was about 1,2m long, 0.5m wide and 15cm thick. an yes, i nailed the foremost part of the plywood to my mold to keep everything in place.

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as i went to my veneer supplier, he was sold out of 1,5mm ash veneer. so i took veneer with 0.9mm thickness. the price for the cores stayed the same, but now it has more layers of veneer: 12plys in the middle.

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so, bases are cut out, core nearly done - just need to bend the edges and figure out how to lay everything up!
plywood freeride industries - go ply, ride wood!
plywood
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Re: number two!

Post by plywood »

i just pressed the first ski.

as my skibuildingskills grew with the first pair i wanted to do some sidewalls on this pair. but i didn`t want to use ABS - it seemed to be a potential source of delamination and complicated to glue...
so i wanted to try something different. i based my plans on the kam`s idea with the epoxy sidewalls. since they wrote that such sidewalls were not as durable i thought to reinforce this construction with fibreglass would be a good idea.
but i don`t wanted to use some sinle roving above the edges because this would have changed the flex of a ski too much. that`s the reason why i took some fibreglass flakes. my plan was to cut out the core 4mm thinner than the base with the edges. the leftovers of the core would be used as some kind of dam, positioned with a little setback besides the base. so this would create a flute which i could fill up wit an epoxy/fibreglass flakes mixture.

in theory it seemed to be a great idea.

but once again practice showed it`s ugly face! creating the flute was no problem. but then troubles began. so i filled the flute with some flakes, soaked them with epoxy....flakes sticked to my gloves, i went out of epoxy but the flakes were still nearly dry, mixed again epoxy, the flakes soaked up everything, epoxy all over the woodcore, flakes swimming ON it.... but not in the damn flute!
well, somehow it went better as i widened the flute - with the result that i needed more flakes and even more epoxy! so all in all i needed nearly 1kg of epoxy just for the sidewalls. (on my first ski 1200g were enough for the whole ski).

all in all it barely was doable.... so i`m just hoping that everything comes out usable.... or i`ll be really pissed of.
well, i dread to think about doing this whole procedure once again for the second ski. :?
plywood freeride industries - go ply, ride wood!
plywood
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Re: number two!

Post by plywood »

oh yeh, i nearly forgot the best part of it.

guess where the 1kg of epoxy i used did flow during pressing?!


YES!
all over my mold and "pressframe"! rivers of epoxy floating everything. a little tsunami over my workspace. so i`m really looking forward... i not only have to hope that the skis come out usable, no, i also have to hope i don`t have to build a new pressframe! (as you may remember, my press frame is a bit special, it`s made out of cloth - and that doesn`t work well with epoxy because then the cloth is glued to the mold. :| )
plywood freeride industries - go ply, ride wood!
davide
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Post by davide »

Yours parents will be quite happy to have a new epoxy floor...
plywood
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Post by plywood »

finally they are done

as i wrote in a further post i had to use really a lot of epoxy for the sidewalls on the first ski.
and so it was on the second ski - with a tiny little difference. because it needed so damn much i nearly ran out of epoxy on the second pair. and if i say "nearly" i REALLY mean nearly. at the end there was not one single gram left and i had serious problems to get the grafic layers wet. so this were some scary moments, i already saw my time of failure and in my head the ski already was on it`s way to the trashcan.
but the hope dies at last and so i did my best to turn the situation to my side. so during pressing i increased the pressure up to 5 bar (in comparison: the other ski i pressed with 1,75 :D )

but all things come to an end, somehow. out of press the ski didn`t look as bad as i feared. well, it was visible that the layer under the topsheet was not that wet...there were a bit more little air locks under the topsheet. but nothing serious...

so i cut them out with JIGSAW:

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hehe no seriously. i really took (a) jigsaw, but not the one from SAW. but back to topic. so i tried several saw blades...and the sidewalls killed them ALL. with some blades i hardly managed to make a cut of 5cm lenght, then their teeth were gone and they were blunt. the blades that worked best were some made for cutting hard wood, made out of HSS (highspeedsteel). they hold out pretty long: up to 30cm! :D

as you can imagine it was a big a pain to cut the skis out. so i was prepared for the worst as i began to bevel the sidewalls. but beveling went surprisingly well! was really fun to do it. the dust looked like little snowflakes, so it created a feeling of winter all over my workspace - if the climate won`t produce any winter i got it at least there.

during beveling i recognized that my woodcores had shifted a bit. so on one side i became really nice looking black fibreglass sidewalls - on the other the woodcore is just covered with a small layer of epoxy and a few fibres, so the wood is visible. fortunately it`s symmetric on both ski, so on each ski the outer sidewalls are black and the inner sidewalls (the ones facing each other if you put the skis side to side) are wooden.

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and now for the grafic. after my first pair i wanted to build green skis. so i started searching for a green cloth in my mothers working room. there in one box i found this nicely painted green cloth and i knew this was what i was looking for. so i did some tests with it. these tests showed me that i had to put white paper behind the cloth so that it would get a bit brighter and get more contrasts. i really like the result - even if the colour of the cloth faded a tiny little bit.

oh yeah, and my mother got this cloth from...somewhere far east (i don`t remember where exactely) about nearly 30years ago. so i finally freed it :D

below you can see some more detailed views. sorry for the large pictures - but they have to bee that big, otherwise you couldn`t recognice the full drawings.

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plywood freeride industries - go ply, ride wood!
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RoboGeek
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Location: Middle of a cornfield...

Post by RoboGeek »

love that cloth! Now get skiing and report back!! 8)
I used to be a lifeguard, but some blue kid got me fired.
collin
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Joined: Sun Oct 23, 2005 10:19 pm

Post by collin »

Looks like Indonesian batik to me.

Nice skis man.
------------------Take nothing I say as expert advice------------------
G-man
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Joined: Sat Mar 25, 2006 3:58 pm
Location: northern sierra nevada

Post by G-man »

Amazing as usual. The cloth is so great... what a score. Quick thinking in crisis mode.

G-man
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