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Posted: Thu Jul 22, 2010 11:26 am
by twizzstyle
dorabito wrote: I am going to shape and profile it by numerical control cutting on an aeromodelling shop close to my house
:D Nice! Now you're talking! You'll have some killer cores! And yeah, at 10mm underfoot, 2 layers of fiberglass top and bottom won't be overly stiff actually. I do my skis 13mm underfoot, 2mm at the tips, with a single layer of triax top and bottom, and they're a little on the soft side (which I prefer for my kind of skiing).

I think you're on the right track, you just need to work out how to get even pressure with the clamp press (that will be your biggest challenge at this point). Keep up the work!

Posted: Thu Jul 22, 2010 11:28 am
by Richuk
You don't need to compressor for a pneumatic press, check your parents garage for a tyre inflator/foot pump. There's a thread here that highlights the right connector, so you can make this work.

Are you sure you can't get hold of hold of a bit of box section or angle iron - someone must have it as scrap. See what you can find locally - 1 metre or so from one place the rest from another. No money means getting creative!

PVC hose is cheap enough - I think the high pressure hose is red. Think 'samples'

Your parents will come round once they see some results.

Posted: Thu Jul 22, 2010 11:33 am
by dorabito
Richuk wrote:You don't need to compressor for a pneumatic press, check your parents garage for a tyre inflator/foot pump. There's a thread here that highlights the right connector, so you can make this work.

PVC hose is cheap enough - I think the high pressure hose is red.

Your parents will come round once they see some results.
Good Idea! I am not sure if it will create enough pressure, but I can try it.
Thanks for sharing

Posted: Thu Jul 22, 2010 11:42 am
by Richuk
Find the post and you'll see it working.

Posted: Thu Jul 22, 2010 11:43 am
by twizzstyle
dorabito wrote:
Richuk wrote:You don't need to compressor for a pneumatic press, check your parents garage for a tyre inflator/foot pump. There's a thread here that highlights the right connector, so you can make this work.

PVC hose is cheap enough - I think the high pressure hose is red.

Your parents will come round once they see some results.
Good Idea! I am not sure if it will create enough pressure, but I can try it.
Thanks for sharing
Even 20psi with a firehose is better than a clamp press. Lots of people use vacuum pumps, and with that you're only getting ~14psi (atmospheric pressure) at most. A tire pump will give you more than enough, you'll just want some kind of valve so once its up to pressure you can close it up and shut the pump off. Those pumps aren't meant to run continuously like a vacuum pump.

Posted: Thu Jul 22, 2010 11:51 am
by dorabito
twizzstyle wrote:
dorabito wrote:
Richuk wrote:You don't need to compressor for a pneumatic press, check your parents garage for a tyre inflator/foot pump. There's a thread here that highlights the right connector, so you can make this work.

PVC hose is cheap enough - I think the high pressure hose is red.

Your parents will come round once they see some results.
Good Idea! I am not sure if it will create enough pressure, but I can try it.
Thanks for sharing
Even 20psi with a firehose is better than a clamp press. Lots of people use vacuum pumps, and with that you're only getting ~14psi (atmospheric pressure) at most. A tire pump will give you more than enough, you'll just want some kind of valve so once its up to pressure you can close it up and shut the pump off. Those pumps aren't meant to run continuously like a vacuum pump.
I have some ideas. I'll see what I can do.

Posted: Thu Jul 22, 2010 1:25 pm
by skidesmond
Lots of activity today...

We're all here learning from our own mistakes and from others. That's why this place has become such a cool community. It takes a lot of knowledge and skill to make a "good" ski never mind a great ski. And we're all here to pass around that knowledge. Using top of the line, expensive material doesn't make a great ski. There's so much more to it and I think you're finally seeing the light.

People here are giving advice based on their experience and from that of others.

A wood core of ash vs poplar vs maple vs pine will all make totally different feeling skis even if everything else is the same. Like Twizz said also, a mm or 2 here or there can make a big difference.

Stick with your original plan. I think your original core of 2mm-10mm-3mm is good. If you're putting 2 layers of triax FG below and above the core you'll have a darn stiff ski. Once you ski on it decide what you like and don't like.

Trust me you'll be making more skis. Maybe not this year but you will be. You'll want to get a job after school for $$$$$ to make skis.

I'm also building a GS ski for racing.

Posted: Thu Jul 22, 2010 1:51 pm
by dorabito
skidesmond wrote:Lots of activity today...

We're all here learning from our own mistakes and from others. That's why this place has become such a cool community. It takes a lot of knowledge and skill to make a "good" ski never mind a great ski. And we're all here to pass around that knowledge. Using top of the line, expensive material doesn't make a great ski. There's so much more to it and I think you're finally seeing the light.

People here are giving advice based on their experience and from that of others.

A wood core of ash vs poplar vs maple vs pine will all make totally different feeling skis even if everything else is the same. Like Twizz said also, a mm or 2 here or there can make a big difference.

Stick with your original plan. I think your original core of 2mm-10mm-3mm is good. If you're putting 2 layers of triax FG below and above the core you'll have a darn stiff ski. Once you ski on it decide what you like and don't like.

Trust me you'll be making more skis. Maybe not this year but you will be. You'll want to get a job after school for $$$$$ to make skis.

I'm also building a GS ski for racing.
You are right. We are all learning, often from mistakes.
Good luck with your ski

Posted: Thu Jul 22, 2010 3:48 pm
by MontuckyMadman
Image

Posted: Thu Jul 22, 2010 4:00 pm
by chrismp
lol, montucky!

@dorabito: no need to get angry...all of the answers to your questions could be found in this wonderful forum if you'd only start reading.
i read almost every single post on here before starting to plan my press and now i've got a press that works like a charm and produces great snowboards.
there's folks like you asking the same old questions every couple of weeks on here, so don't get mad when you're told to use the search function.

fyi my press cost me about 100eur (INCLUDING MONTUCKYS CORDURA BAGS!!!), which i guess should be in your budget. so i would recommend going the same route since it's the cheapest way to build a pneumatic press imho (have a look at the threads i posted and feel free to ask if something is unclear to you)

good luck with your project!

Update

Posted: Tue Jul 27, 2010 10:00 pm
by dorabito
Update:
I have designed a new layup, probably the definitive one. I changed it due to advices from people from this forum (thank you guys). It is posted at the first post.
This is the "sandwich":
Image

CLEAR TOPSHEET
750g/m2 FIBERGLASS
OBECHE/OAK CORE, ABS SIDEWALLS and TIP/TAIL SPACERS
750g/m2 FIBERGLASS
340 g/m2CARBON UD-TAPE 25mm. (twice)
VDS RUBBER FOIL
STELL EDGES and P-TEX BASE



This is the core lamination:

sidewall/obeche/oak/oak/obeche/obeche/obeche/oak/oak/obeche/sidewall


The heights of the core are:

Tip: 2mm.
Waist: 12mm.
Tail: 3mm.

Posted: Wed Jul 28, 2010 2:22 am
by chrismp
considering your wood config...i always thought people put in one strip of harder wood next to the sidewalls to get the best edge hold. correct me if i'm wrong.

Posted: Wed Jul 28, 2010 2:34 am
by dorabito
chrismp wrote:considering your wood config...i always thought people put in one strip of harder wood next to the sidewalls to get the best edge hold. correct me if i'm wrong.
I am doing this to have a better power transmission (as the binding/plate screws would fit in the hard wood, it would maximize the energy transfer, from tip to tail)

http://www.skibuilders.com/howto/skicon ... tion.shtml
There is an explanation at the bottom of the page

Posted: Wed Jul 28, 2010 2:51 am
by chrismp
yeah, i can see why you're putting oak in the middle, but why not also on the edges? (see last graphic on the link you posted)

Posted: Wed Jul 28, 2010 11:52 am
by dorabito
chrismp wrote:yeah, i can see why you're putting oak in the middle, but why not also on the edges? (see last graphic on the link you posted)
Well, mainly, because:
1- It would be too stiff (with 6 strips of oak), and especially because:
2- I only had that ammount of oak, and the only place I know who sells oak wood in Madrid is 40 miles away from my house :?
One more thing: when shaped, the core will have oak wood stuck to the sidewall at the waist.