Ski Builders Forum

Hello,

as some of my friends frequently ask me how I build my skis, it's time to make a detailed documentation of the next build.

Building the ski template

As I don't have a CNC router, I do create my ski template off the computer. Well, half way. I have written a small program that calculates the sidecut: It tells me how wide the ski is at each point. So, I use the results of the program, and draw them on the wooden template (in this case 22,222 meters radius). The tip and tail are drawn free hand:




Next, I roughly cut the shape with the jigsaw:




Making the sidecut nicely is the hardest part. I built a ruler for it (Some L shaped aluminium with some holes in it) - using it creates quite a nice even sidecut:




Both sides of the sidecut routed:




For the tip, I use another ruler which is bent:




And the same for the tail:




To smoothen transitions, tip and tail sections are sanded using a selfmade 90° sander:





Building the other templates

As the template will never be exactly symmetrical, it's time to create some more templates:

1) The ski template already built
2) one more having the ski shape (for making perfect symmetry and as a backup)
3) one for the base (having 2mm less on each side)
4) one for the woodcore (having 9.5mm less on each side - with the router bit I use for routing the wood core it makes the woodcore 6mm thinner on each side than the ski - leaving 6mm space for the poured sidewall).

So, how to make the template perfectly symmetric?
After routing template 2 using template 1, template 2 is turned around (so what was on the left before now is on the right and vice versa) and connected with template 1 again. now, template 2 is routed again using template 1, and template 1 is routed using template 2. This step only takes away very little material on some points, and the result is that both templates are symmetrical (left-right symmetry).

After having template 1 and 2 finished, routing 3 and 4 is an easy job.

All 4 templates lined up, from left to right: 4, 3, 2, 1

Quite the process. Truly handmade.

I use only one "haldftemplate" for cutting bases and cores. Then you can count with symetrical shape. Just do one side then flip and cut the other side :) For me it is easier, because I use wooden sidewalls, which I glue to the core after I cut the shape according to the halftemplate....

But I really like your way with L profil bridge to cut the exact sidecut..... I use the method aka brush it and check it until it is absolutely perfect for your eye. Fortunately my eyes are quite ok for now... But in the future, maybe I ll inspire with your method. Very similiar method use guys from community skis. They have thing called shaping table and there they can via screws and iron profiles make lots of shapes.....

Hi,

used the halftemplate method as well- But I had trouble imagining the final shape, so after seeing the complete template for the first time I did quite some adjustments on tip and tail.

So for this ski, I decided to go full template again. A bit more work to start with, but you exactly see what you get.

Regards
Philipp

I spend a lot of time with drawing skis in Microstation PowerDraft V8i ... We got "free" license of this software in school and nobody want us to uninstall it.... So I am happy I have such a software for free. And you can intuitively draw there skis according radius, dimensions.... Very powerfull for imagine which shape you want to get.

But I ve done so many shapes I couldn t decide which choose :D That is my problem, many ways but can t do the decision for the right one....

pavelbozak wrote:But I ve done so many shapes I couldn t decide which choose

Same thing here

Making the sidewall pouring mold

Next, I create a mold for pouring the sidewalls. A bit of extra work, but imo worth it. I'm sometimes thinking of doing it like all the others, but well... more work, less PU used.

The mold consists of a base, a polystyrol layer for creating the 0.8mm rabbet, and a top having the negative ski shape as hole (Who can give me a nice english expression for this?)

So, the top first:
I use a 15mm thick wood which is later planed down. I draw the outline of the ski on it, about 1,5mm wider on each side. Like this, the core can shift a bit in the press (though that shouldn't happen the way I do it) and there is still sidewall everywhere.




I also add 4 bays where the resin for the sidewall will also go in. This is used later for aligning the core in the press.




After cutting out the inner part roughly using the jig saw, I rout away everything inside the drawn line free hand:




The middle section (where the ski is thick) and the bays are beveled for easier mold release:




Checking if everything fits: The ski template has a bit of space on each side of the mold.




So, lets go for the 0.8mm polystyrol:
The sawn out middle of the 15mm thick wood is quickly routed down to be 11.5mm thinner on each side than the ski.
Then it is used to cut out the polystyrol:




Finished cutting:




After this, all 3 parts are laminated:

Making the wood core

For all my woodcores I use ash, as it is the only wood I can get easily. I buy 2m stripes 25mm wide and 15mm high. (correct me if stripes is the wrong word)

First thing I do is comparing the stripes and grouping them. I group them by bending stiffness and evenness of grain: The ones with the most even grain are used as the outermost stripes, the others for the inside.
You may think "why the ****, most of the outer stripes is routed away anyway". Well, not the way I do it. It is quite some extra work, but I want my outside stripes to be all the way over the ski (like a wooden sidewall). Why? When riding hard snow, the power transmission from the edges to the ski middle is quite important. And I think that the outside stripes help doing this if the are bent along the sidecut.

A picture of my ghetto style bending stiffness test:




After the wood is sorted (I buy wood for many skis so I get a lot of even stripes) its time to glue some wood together:




A quick run through the planer afterwards to have nice surfaces again:




So this is the inner part of the core. Now I'm doing some simple math and use the ski template to draw the sidecut of the ski (in this case 22,222 meters) over the whole length of the wood (without tip and tail, just a single line for the radius - have to use the template in 2 positions to achieve this).
Afterwards, it is roughly sawn with the jigsaw:




The same way I'm using the template to draw the radius on the ski I'm using it to rout the radius:




Finished the first one:




The first one is used as a template for the second one:




Both cores finished:




Now its time for the outer stripes - some more gluing. After the outer stripes are attached, the core ist about 3mm too wide on each side - it will be routed away later.




After gluing the outer stripes, one side of the core is planed carefully - it is the lower side of the core and won't be machined any further.




Now its time to bring the core into its final shape - roughly sawing is first:




Routing it down to its final shape is done in 2 steps. Why? Because wood likes to move. If I would take away the 3mm on each side in one step, the wood would move more (as the outer stripes are not in a relaxed position, they bend the whole core a bit - if wood was steel, they would do exactly the same amout equalizing the effect. But as wood is a natural product, the 2 outer stripes don't exactly behave the same).
So I take away about 1.5mm first using the template made for the base and a router bit taking away 2mm.




Finally going for the final shape using a beveling bit and the template made just for this:




Finished shaping:




2 things are missing before the core is really complete:
- routing a 0.8mm rabbet in the lower side for the teeth of the steel edge
- planing the wood down to the final thickness

Making the rabbet

As the sidewall will be 6mm thick, 6mm of rabbet need to be routed in to woodcore to have a total of 12mm rabbet. I want this much rabbet (only 8mm would be needed if you lay up superprecise) for 3 reasons:
- If the core shifts a little bit, I have 4mm "buffer"
- with this much extra rabbet, the fibres are hardly bent at all by the teeth of the edge => fibres work best if they are dead straight, and with this amount of extra rabbet I get close to that.
-The VDS rubber I get is 13mm wide. As the rubber overlaps the edge a bit, the rubber should fit completely in the rabbet

Ok, lets go:

I built a simple depth stop for the router. It is fully adjustable as it is made of 2 M10 screws. Using this I can rout the 6mm precisely.







The result:

Nice work. I'm a big fan of a consistent width stringer on the outside of the cores as well.

I also agree with consistent wood stripes above the edges....

Additionally ,my opinion is that there is no need for plastic sidewalls if you have nice stripes of wood to place them above your edges. I have not tried ash for sidewalls yet but my girlfriend´s dad has a pair of really oldschool ash skis (maybe 60 year or more old) in his cellar and the wood is still in super condition. The ski is still flexy.... It is made from only one piece of wood and without glue/fiber reinforcement, so wooden sidewalls seems to me much better than any plastic...

Wood handles impacts badly. Nice journal.

Making Bases

As some of you surely read somewhere else or experienced yourself, the base material likes to warp. That is why I do the base work in 2 steps:

First, I use the ski template cutting the base using it. This leaves 2mm extra on each side of the base, so even if the base warps I can still get to the final shape.




After this is done, I let the bases rest for at least one more day. Then, they are routed to their final shape using the base template.

Attaching the base to the template using double sided tape:




2mm extra on each side:




After routing it I use the stable template below to sand the sides and edges:




In this case, one of the bases warped more than 0.5mm after cutting it - before routing. I want my work to be precise, more than 0.5mm off definitely is not. After routing them with the base template, I can not detect the slightest warping.
That's it for the bases already, bending and attaching edges is next.

Bending and attaching edges

I only do full wrap edges - I like it this way. As I think of all my skis as touring skis (though some get a normal alpine binding), I want to have edge everywhere anyway (sticking the skis in the snow for putting on/removing skins).
I use 4m long edges, so I only have one "seam" in the entire edge.

For bending the tip I like moving from the workshop to the living room - I like doing this in front of the TV :)




I start marking one tooth as the middle tooth - it will always be in the middle of the tip:




For bending, I use a modified nipple plier:




After some work it looks quite good (by the way, this is the base template I use of course)




Then its time for the workshop again. The edge is glued to the base on about 2/3 of its entire length. I do not use superglue but fast curing epoxy. I just don't want to have the much weaker superglue in the final ski.
Below the base and edges there is the original template of the ski. Nice method of aligning everything the way it should be.






When the edge is glued on 2/3 of the base, it is time for bending the ends. Now base and edges are aligned properly and the result will be precise.




Ends trimmed and ready for getting glued to the base

Very tidy looking work there pmg, I'm impressed.

I also bend the edge to the base mold and then clamp to it when gluing on edges, stops any base warping from affecting the final ski.