core question

[originskis]

hi, i am about to build my first ski and had one question. the skis im making have a 34cm tip and 24cm tail. the total length is 168cm so that means that between contact points it is only 110cm. should the core be only 110cm? longer? where should the tipspacer start? thanks!

[skidesmond]

Do you have a design of the ski you can show us? This a rocker design or something? Most of my skis are basically all mountain skis and have tip length of 120mm and tail length of 60mm.

[originskis]

i don't have a pic but it has serious early rise with traditional camber. i'm thinking the core should be part of the tip for a while.

[MontuckyMadman]

10-15 cm of tip and tail spacer seems pretty common.

[Alex13]

I don't know that much about skis, but my thoughts would be you'd want the core to extend a few cm at least past the running length (contact points) into the tip/tail.

What Montucky said sounds about right, which would make your core 138cm - 148cm.

[SHIF]

My rockered ski design is 185cm long and has only 90cm between the contact points with positive camber and sidecut underfoot. The early rise tip is 53cm long and the early rise tail is 42cm long. The tip filler length is 18cm long and 9cm in the tail. The core profile is exactly the same as on my fully cambered skis, just the ski footprint shape and press form is radically different.

Held base to base and de-cambered (squeezed together in the middle) the rocker naturally increases on both ends and the running length is reduced. The "weighted" ski looks almost like a full length rocker.

Cheers,

Some pics on my www link...

[originskis]

thanks a bunch all of you. i think im gonna go with 15cm tipspacer in the tip and 10 for the back. so stoked to get these done with!!!!

[falls]

I think you're already on the right track but will support the same views anyway.
I measured all my production skis and they tend to have 15cm of tip spacer.
I think in an early rise/rocker tip you definitely want wood core in the rockered part to provide strength. My design had a gradual rise of 2cm over 25cm then a normal tip shape on the end for a further 5cm of rise (tip height 7cm). I used only 15cm of tip spacer material in this. Total flat ski length was 173cm. My cores were 145cm long (tail early rise too).

I was reading about Gotamas (the new ones with tip rocker, I think it was them anyway, but the theory is the same) and they actually have quite a stiff flex in the tip. Their theory was that the tip is already "pre-flexed" by being off the snow. So making the tip soft is actually bad because it just adds susceptibility to being knocked around in crud. If the tip already curves up out of the snow, making it stiffer helps it plane upwards. The best way to increae stiffness is with core rather than heaps of glass on floppy plastic.

Long winded way of saying 15cm tip spacer and 10cm of tail spacer sounds good.

[originskis]

ya that makes sense. i am going to put carbon tape in the tips to make them stiffer