Wooden backcountry skis

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andrey
Posts: 6
Joined: Sat Dec 08, 2012 9:59 am

Wooden backcountry skis

Post by andrey »

Here is my build process. Any comments are appreciated.


JSquare
Posts: 102
Joined: Fri Sep 14, 2012 1:59 pm
Location: NH

Re: Wooden backcountry skis

Post by JSquare »

This is a really neat process.
The wooden base (and hot bending of), the rod tensioned press, and the DIY tools (bandsaw, belt sander), and general use of hand tools stand out as pretty unique and clever. Looks like a well thought out process all in all

Have you ridden them? How do they ride? Any issues you're looking for feedback on or areas you want to improve?

Because you solicited feedback-- and because i think its awesome you posted looking for it:

One thought-- I'd be curious about your finishing process. I saw a pretty big improvement going from dry to wet sanding for the edges--and i have to believe that you'd benefit from a wider/flatter sander for the base.

Are you getting some epoxy bleed to the base? If its raised off the base, you should be able to grind out. If its flat with the base, then it means there's a lack of flatness either in your press mold or in your wooden base. Does it disappear when you wax it?

andrey
Posts: 6
Joined: Sat Dec 08, 2012 9:59 am

Re: Wooden backcountry skis

Post by andrey »

Thanks a lot for your message.

Yes, my friends and I did ridden this skis a lot. They are designed for making a ski track in deep snow, going uphill in powder with backpacks and similar activity. The wooden base helps a lot when going uphill without using ski skins. Flat wooden base is faster than ski with crowns pattern like many backcountry skis have. And wooden base does not need to wax it.

You may see a clip from a trip with my skis in the team:
350 km distance of run in a very hard conditions.
IMG_20200302_120206.jpg
IMG_20200302_120206.jpg (314.84 KiB) Viewed 84 times
All people who used this skis cannot value their downhill and freeride qualities, mostly because they are not professional freeriders and special ski bindings are installed. I think a wooden base is not so fast as UHDPE for sure.

How a wet machine sanding looks like?

If a wooden base has cracks in it, some amount of epoxy may bleed to the base, but it does not create hills. I think it is a capillary effect, not the consequence of lack of flatness. Some amount of epoxy leaks out near the edges and I grind it out. Sometime I have gaps between edges and base, I have to fill them with epoxy before finishing. I do not know how to ideally fit edges without gaps.

What I would like to ask the community, how I can reduce the weight from about 1650 grams to about 1200 per ski.

I use an ash core 2mm - 12mm - 2mm thickness. Would pine core be a lot brittle and weaker than ash?

I use 120 gsm UD carbon and 311 gsm diagonal bidirectional glass layers beneath and above the core. Does it makes sense to use only carbon beneath the core?

Note this skis are not used for speed riding.

mammuth
Posts: 365
Joined: Tue Oct 28, 2014 3:48 am
Location: somewhere in the alps

Re: Wooden backcountry skis

Post by mammuth »

Cool!

If you like to go lightweight switch to full carbon fibres. You will have to make the core thinner as well (if you stay with ash) which will also shave off some weight...

But ... if your skis are not made mainly for freeride or high speed you can change to another more lightweight wood. This combination with carbon will give you less weight.

Pine core is fine, flexwise its not so far away from ash. But its much more soft, think about that in terms of binding screws.

Even more lightweight (and less strong) is poplar.

For the wooden base you need a hard wood like ash!

Regarding the edge gaps. You tack your edges with superglue?
Tom

andrey
Posts: 6
Joined: Sat Dec 08, 2012 9:59 am

Re: Wooden backcountry skis

Post by andrey »

Regarding the edge gaps. You tack your edges with superglue?
Yes, I use akfix superglue with spray fix.

mammuth
Posts: 365
Joined: Tue Oct 28, 2014 3:48 am
Location: somewhere in the alps

Re: Wooden backcountry skis

Post by mammuth »

On every tab of the edge (which is not good) or on every X tab?

If the base wood is soaking the glue too much, try a gel type. I assume the edges have no gaps when you fix them with glue, the gaps are coming during pressing?

And try just using the superglue without spray fix.

P.S. you clean your edges with acetone before?
Tom

JSquare
Posts: 102
Joined: Fri Sep 14, 2012 1:59 pm
Location: NH

Re: Wooden backcountry skis

Post by JSquare »

mammuth wrote:
Mon Sep 14, 2020 2:03 pm
Cool!

If you like to go lightweight switch to full carbon fibres. You will have to make the core thinner as well (if you stay with ash) which will also shave off some weight...

But ... if your skis are not made mainly for freeride or high speed you can change to another more lightweight wood. This combination with carbon will give you less weight.

Pine core is fine, flexwise its not so far away from ash. But its much more soft, think about that in terms of binding screws.

Even more lightweight (and less strong) is poplar.

For the wooden base you need a hard wood like ash!

Regarding the edge gaps. You tack your edges with superglue?

Strength and stiffness can be a weird concept. This might help.
Ash is pretty extreme in general. It is stiff, heavy, and tough. There's a reason its used for baseball bats. The comments on screwing into wood are on point. Some folks will make a core with a wood like ash under foot and lighter woods elsewhere.
Ash > poplar > pine
This might help-- all in one simple table, different strengths, flex, and density.

http://workshopcompanion.com/KnowHow/De ... rength.htm

I've made some boards with pine/ cores because i found a local source of it. Lighter and more flexible than poplar.
I would take a swing at estimating the weights of all of your components and seeing where all the weight actually is and look for a big driver.

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