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Posted: Fri Jun 25, 2010 6:30 pm
by skidesmond
Nice! I made a pair and used them for beer-league racing also. Had a great time on them. They were more of an all mtn ski than a racing ski but they did the trick.

viewtopic.php?t=2188&highlight=

I have some new designs in the works, geared more for GS.

So far all my lay ups have been fairly basic:

ptex base
egdes
vds rubber of the edges
22oz FG
ash wood core 12mm
22oz FG
top sheet -either cotton cloth or veneer

I use an all wood core, tip to tail and side to side. No plastic tip/tail spacers or plastic sidewall. Trying to keep it simple for now. But I may try more complex builds later this year. But so far I've been very happy with the results.

Posted: Sat Jun 26, 2010 11:51 am
by dorabito
skidesmond wrote:Nice! I made a pair and used them for beer-league racing also. Had a great time on them. They were more of an all mtn ski than a racing ski but they did the trick.

viewtopic.php?t=2188&highlight=

I have some new designs in the works, geared more for GS.

So far all my lay ups have been fairly basic:

ptex base
egdes
vds rubber of the edges
22oz FG
ash wood core 12mm
22oz FG
top sheet -either cotton cloth or veneer

I use an all wood core, tip to tail and side to side. No plastic tip/tail spacers or plastic sidewall. Trying to keep it simple for now. But I may try more complex builds later this year. But so far I've been very happy with the results.
woow a ski with out plastic!
How are they on durability? I´m looking for a construction with hight durability so I don´t know if this construction is good for me, but thanks for sharing!
P.D.: viewtopic.php?t=2188&highlight= : THESE GRAFICS ARE AMAZING!!!!! I just loved them. How have you done them?

Posted: Sat Jun 26, 2010 6:40 pm
by MontuckyMadman
desmond. If you had no plastic what were your dims at tip and tail? 2mm?
or atleast 1o mm back from the tip?
Those must be some insanely stiff skis. Do you weigh 250lbs?
I guess cause they are so skinny at the waist it must work out.

Posted: Sun Jun 27, 2010 2:54 pm
by skidesmond
dorabito - The skis held up very well. I raced on them all season except for 1 or 2 races where I used my Volks as a comparison. The top sheet is cotton fabric from JoAnns. It was left over material from a NASCAR quilt my wife made for a friend of ours. I used epoxy over the cotton fabric.

Montucky- The tip/tail are 3mm and 11m thick at the center. They're on the stiff side but have a nice even flex. No chatter, carves really well on hard pack. Holding steady 195-200lbs...... so far.

I think I used maple and poplar on that ski. I noticed for racing they were great in the turns, the more you leaned on the front the more responsive they became, but when it came to the straights they were a bit slow... could have been me also :D

My new "GS-Comp" design will be 114-68-100 in 170cm, 175cm and 180cm. I'm going to try to soften the ski a little this time, with 2mm tip/tail and 10mm at the center. I think design will work well when I'm not racing too.

Plan on using the same type of layup using ash for the core.

What do you think about this construction?

Posted: Tue Jun 29, 2010 3:03 am
by dorabito
Do you think this construction will be too stiff (I wheight140lb)?

TOP SHEET CLEAR
CARBON FIBER
BI-DENSITY WOOD CORE, ABS SIDEWALLS and TIP/TAIL SPACERS
TRIAXIAL FIBERGLASS
TRIAXIAL FIBERGLASS
CARBON FIBER
RUBBER (anti vibration and edges bonding)
P-TEX BASE and EDGES

I am using an epoxy resin with this adherence: 350 kg/cm2

Posted: Tue Jun 29, 2010 3:35 am
by skidesmond
Depends on the core dimensions. But IMO I think that will be a stiff ski. I haven't built as many skis as others in the forum but my skis have been running on the stiff side. I've made variances in the core thickness from 10-12mm and different lengths and shapes to see how these differences feel. All are torsionally stiff, which I like, and have a firm flex which I'm looking to soften just a bit.

food for thought - I went to buy a racing ski for my daughter last season. The owner of the ski shop recommended a jr racing ski for her since she was under 140lbs. He said she would have a really hard time bending an adult racing ski.

We would all like to build our first ski/board perfectly but there's so many variables. You may want to think about skipping the CF for your first try. Also core design/thickness can make a huge difference.

Obeche (Triplochiton scleroxylon) Core

Posted: Wed Jun 30, 2010 12:02 am
by dorabito
Do you think it is a bad idea build a core completly of obeche with this shape: 10mm. under foot, 2 mm. tip, 3mm. tail?
Probaly I will use the layup at the first post
Image

Posted: Wed Jun 30, 2010 9:59 am
by OAC
How much material do you have? I terms of fiberglass and epoxi.

Just a suggestion: Make some test pieces of your core (or reg. lumber) 60 - 80 cm long, preferebly tapered, 10 cm (or so) wide, 2 - 3 mm thick and reinforce them with fiberglass on both sides and you will get an idea how your tip and tail will be. Just a suggestion...

Posted: Wed Jun 30, 2010 1:57 pm
by skidesmond
Making test pieces is a good idea. You'll get a general idea how soft/stiff the ski will be. I never heard of obeche wood so I can't say one way or the other. Look for it on the Young Modulus (do internet search) and see how it compares to other woods like ash, maple, etc.

Like others have warned, be aware that you may get funky results/warping when you do an asymetrical layup. I haven't used CF yet and I would leave it for the first time around.

Posted: Wed Jun 30, 2010 5:35 pm
by Damon
Concerning the asymmetrical layup: assuming you're using uni exclusively as additional reinforcement, you'll only see changes in camber - no 3 dimensional warping (twist).

Edit to add, uni in the 0* direction of course...

Posted: Thu Jul 01, 2010 8:23 am
by dorabito
skidesmond wrote:Making test pieces is a good idea. You'll get a general idea how soft/stiff the ski will be. I never heard of obeche wood so I can't say one way or the other. Look for it on the Young Modulus (do internet search) and see how it compares to other woods like ash, maple, etc.

Like others have warned, be aware that you may get funky results/warping when you do an asymetrical layup. I haven't used CF yet and I would leave it for the first time around.
Unfortunately I only have enought material to build the pair of skis (excluding the very small amount of wood that will be cutted of)
I am thinking of use only fiberglass but I wonder if it won´t be strong enoght to resist aggresive turns at 30 MPH...

Posted: Thu Jul 01, 2010 12:10 pm
by skidesmond
IMO, If you're using 22oz tri-axial FG I think you'll a get ski that is stiff. Assuming the core dimensions haven't changed from previous posts. Also check the Young Modulus of the wood you are using. If it's soft you may want to add 1 or 2mm to the core but I think 2mm in the tip and 3mm in the tail will be fine.

Idea for Grafics

Posted: Thu Jul 01, 2010 1:24 pm
by dorabito
What do you think about this grafics?
Image

Posted: Thu Jul 01, 2010 1:57 pm
by skidesmond
Looks sweet! Time to start building!

Use only Fiberglass

Posted: Fri Jul 02, 2010 5:10 am
by dorabito
Hey everyone:
what do you think about this layup:

TOP SHEET
FIBERGLASS
DUAL HARDNESS WOOD CORE
FIBERGLASS
FIBERGLASS
FIBERGLASS
BASE

should I remove one layer of fiberglass from under the core?