Making a park ski- need some help with park specific things

[nick.iodice]

I am looking into making a park ski. here is what I have so far...

-about 190 cm
-butter zone in the tip (a thinner core making it so that the tip is flexy so you can play around with it in the park)
-100% symmetric (easier to build i am guessing, and they will be center mounted)
-maple, aspen, or poplar core (more on this later)
-rubber dampening strips along the edges

so here is what i need help on. I dont know if anything should be built differently for a park ski, so i need some guidance on the following
-tip spacer material- can it be some type of rubbery material? not necessarially rubber, but something that is soft and "rebounds" when hit?
-how thick should the core be? i weigh about 200 lbs and i want the ski to be poppy and responsive, but not so stiff that my shins die if i land in the back seat on a jump
- whats the best way to print onto a cotton fabric for the graphic?

[plywood]

first advice: don`t profile it symmetrical. the tails will feel way too soft. i`d recommend you to do some sort of flattish plattform that goes around 10cm in front of the center and 20cm to the back of it.

i don`t think you have to build anything different for a park ski. tipspacer can be made out of everything i guess. the only thing you might want to think about is that park skis get abused badly so your skis may suffer serious chipping of the topsheet. so i`d keep that in mind when doing the topsheet.

core thickness depends on how much fibreglass you want to use, so it`s hard to say.




- whats the best way to print onto a cotton fabric for the graphic?[/quote]

[nick.iodice]

first advice: don`t profile it symmetrical. the tails will feel way too soft. i`d recommend you to do some sort of flattish plattform that goes around 10cm in front of the center and 20cm to the back of it.

i don`t think you have to build anything different for a park ski. tipspacer can be made out of everything i guess. the only thing you might want to think about is that park skis get abused badly so your skis may suffer serious chipping of the topsheet. so i`d keep that in mind when doing the topsheet.

core thickness depends on how much fibreglass you want to use, so it`s hard to say.




- whats the best way to print onto a cotton fabric for the graphic?

[/quote]

yep- i should have made that a little more specific- i want the dimensions of the ski (tip/tail thickness) to be the same in front and in back of center, not the core thickness. The tail will definitely be thicker than the tip.

as for the topsheet, i have had similar problems with skis that i bought- is there any way to help reduce chipping?

and for the amount of fiberglass, i was planning on using triaxial 22 oz/sq yard, unless there is a better alternative for a park ski (from what it seems, people generally choose between 22 and 19)

[twizzstyle]

190 is long, crazy long. Especially for a park ski. How tall are you?

For park I like a ski that comes up to my nose (for me thats like 160, but I'm tiny)

22oz fiberglass will be fine, just one layer top and bottom.

For the skis that we make, generally we have 12-12.5mm thick core at core center, going down to 2mm on the tip and tail to match the tip spacer material we use (p-tex from either skibuilders or snowboardmaterials.com).

Then we play with the linearity of the taper to control ski flex and "feel". A linear taper from center to tip will give a stiffer ski, while a "curved" taper might make it feel softer. I prefer having a curved taper, it makes the ski solid at the center for good edge control, with nice soft tips for playing on.

I'm not sure how else to describe a curved taper... I use spline curves in my CAD program and play with the anchors to change how its shaped. You can see the core profile nicely on this side shot...



A 1" wide strip of uni-directional carbon fiber down the length of the ski top and bottom will give the ski a lot of pop without adding too much more stiffness (but make sure you do it on top and bottom, or you might get some camber loss/gain after the layup)

[nick.iodice]

^nice! thanks for that. should the carbon fiber threads be running the length of the ski or perpendicular to the ski (assuming that uni directional means that the fibers all go in the same way? if i am mistaken, please let me know).

i know 190 is pretty large for park skis- i have 181's right now and i really love them, but i would prefer something larger. i am almost 6'3 and about 200 lbs so its not too much ski, especially since they are center mounted. i do rails, but never really put too much time into them so im not worried that with the longer ski it will be harder to spin off of rails, especially since i probably wont use these home made skis on them too much.

as for the core profiling, i will try to post a pic of a rough draft that i have of it tomorrow. its too late now and i am far too lazy . i understand the curved taper, but honestly i dont know if i will do it on my first pair since it is a bit tougher. maybe i'll try it though.

EDIT: if anybody is interested, i found that this method for printing on fabric seems to work: (google printing on fabric and it is the first real link)

^it wont let me post links until i have 2 threads, sorry

i wanna use one/a few of my photos (i love photography!) and edit them a bit in photoshop to make a cool graphic.

[Dr. Delam]

That fabric printing method seems fine for letter size pieces but what if you want to print onto ski length fabric? I have used the iron on transfer sheets and they work well. Here is an example of some logos I ironed on to full ski length cotton fabric under Skibuilders' clear top sheet.

[nick.iodice]

i was planning on ironing many sheets onto the fabric, cutting it so it fits in my printer (width wise), and then printing it on a custom length (length of the ski)

[twizzstyle]

^nice! thanks for that. should the carbon fiber threads be running the length of the ski or perpendicular to the ski (assuming that uni directional means that the fibers all go in the same way? if i am mistaken, please let me know).

Yes, the carbon should be running the length of the ski. Remember that the stiffness from a composite goes in the direction of the fibers, having fibers go side to side does basically nothing for a ski. Having fibers at 45 deg however gives you torsional stiffness (hence using triax fiberglass).

[Dr. Delam]

i was planning on ironing many sheets onto the fabric, cutting it so it fits in my printer (width wise), and then printing it on a custom length (length of the ski)

You must have a nicer printer than I have. The longest length my printer will allow me to input is 26 inches. It seems like I should be able to do a custom size larger but no matter what I try to configure, it won't work. My old printer was the same way. I get my full size templates printed at the local office store for this reason.