Making my own ski

[Rsearle]

So I was thinking of making my own ski just for fun but I couldn’t find a lot of helpful material on YouTube so I was hoping someone here could help. I’d like to keep it cheap and was probably just going to use some sort of wood. Any tips, material suggestions or construction methods I should be aware of? Thanks.

[dchristman]

It doesn't get any cheaper or more fun than this Wood ski ... well technically I didn't make it, I found it.

[MattP]

@Rsearle I know this is not exactly what you are looking for but this is a great thread about homemade skis.

 

https://www.ballofspray.com/forum#/discussion/12147/the-how-to-build-a-water-ski-at-home-thread

[Andre]

@Rsearle

"...Eleeski is your father..."

-Darth Vader

[DW]

@eleeski ski - You have not commented on this and it is 2 days old ...

extend wing, cover @Rsearle :)

[loeweb]

I am currently in the process of making my own as well. I'm using oak that has been ripped down to 3/16" and cut into 1,2, and 3 inch strips. I have glued pieces together to make layers with differing joint lines and that's where I'm at right now. I have the rocker form made, and am trying to wrap my head around cutting the concave out of the bottom few layers with a table saw. Also need to find bindings and a fin.

 

So, in the end it will be a bent lamination which will hold form better and be more consistent than a steam bent piece of wood.

[klindy]

You can always try jump skis! The South Central regions very own Elgin Faulkner getting ready to jump at the 2016 Nationals in Idaho. My understanding these are the second pair he made in about a week.

 

 

[wilecoyote]

I highly encourage you to do it. I've built all my own windsurfers since the '80s and plan to make a ski at some point.

 

Don't expect a brand new Denali on your first try. Making your own gear is very rewarding, but it's a journey. I'm both a wood worker and a plastics (fiberglass carbon etc) guy, and my advice would be if you just want to build one without plans to build another, go wood, if you want to start building skis, watch some surfboard building videos to get a feel for how to use the materials and give it a go. Also google" how it's made" they did an episode on how modern slalom skis are made, I can't remember which factory, but don't obsess, you don't need a hydraulic press to make a ski. From that video you will get an idea of how many layers of cloth to use.

 

If you do go composite stick with glass. Carbon is not as strong as glass, and unless you really know what you're doing, mixing carbon and glass is a pretty much guaranteed fail.

 

Finally, try to make as accurate copy as you can of an existing ski that you have access to ski on. That way you can compare your ski to the factory ski to see how you did. Also make it heavy, if your ski weighs the same or less than the one you copied, it will almost certainly break.

 

Good luck!

[eleeski]

@DW I messaged him!

 

Eric

[eleeski]

@wilecoyote The goal is to make it lighter. See where it breaks and reinforce just there. Heavier is not always stronger or better. And carbon is a much better material than glass. Glass has its uses and mixes nicely with carbon if you use the right resin.

 

Denali made something like 64 different designs to get something marketable. Not an activity for those lacking persistence.

 

Eric

[Brewski]

Masterline has these for sale if you are really serious about building skis. I built the press. The molds came from the CarbonWorx Outlaw which was a decent ski back in the day

[BraceMaker]

Heck of a nice looking press! how much does that sucker weigh? Is the press itself pneumatic or is that just an air assist to open the press?

[wilecoyote]

@eleeski, I'm not disputing the advantage of using carbon or of making the ski lighter, but in this case we are talking about first attempts. I've broken a lot of boards with expensive carbon/glass/kevlar layups that I thought should not have failed.

 

The big mistake that people (I was one of them) starting out with composites make is using a mix of carbon and glass (and worse, Kevlar) without properly understanding how the different properties of the materials behave in a finished structure. The issue is not which resin you use but where things go in the structure. If you simply lay carbon over glass, because the carbon is stiffer, the carbon takes all the load until it fails, and then the glass takes the load. So the resulting structure is only as strong as one layer of glass and as stiff as one layer of carbon. For non engineers who cannot properly understand where all the loads will be carried (I fall into this category) the best product will result from sticking with one material. If stiffness is important to you, use carbon, if strength is important, use glass, if both are important, use a lot of carbon. Personally I think people gravitate to carbon (again me too) because they think it's better than glass. It isn't, it's just different.

 

The other reason I recommended glass (specifically S glass) is it is a very good CHEAP material. Plus, because it's transparent when whetted, it's easier for a novice to see voids where the cloth is not fully saturated.

[DW]

@Rsearle : good source for composite materials: US Composites.

[wilecoyote]

@eleeski, I'm not disputing the virtue of carbon, or the goal of making a good light ski. But I stand by what I said. I've built a lot of combination layups that failed when in my mind they should not have. Building something, breaking it, then reinforcing the spot that broke is just a very long tedious game of whack a mole. The problem of mixing materials is that they have different properties, and if you don't understand where and how the load will be carried, you can literally be adding weight without any benefit.

 

I've only recently been educated on the problems of mixing materials, and I wish I had known 30 years ago. Carbon is stiff, glass is strong. That's an oversimplification, but it's a good starting point. If I put a layer of carbon, over a layer of glass, the resulting structure is only as stiff as one layer of carbon, and only as strong as one layer of glass. The carbon will take all the load (because it's stiffer than the glass) until it fails, then the load will be transferred to the glass.

 

This is why I advocate that a novice to stick to simple layups of one material. If you want it to be stiff, use carbon, if you want it to be strong use glass. If you want both, use a lot of carbon. The other big advantage to a novice of using glass (specifically S glass) is that it is transparent. This makes dry spots in the wet out much easier to spot. It's also much cheaper.

[mwetskier]

@loewb -fyi, back in the 60s and 70s the prevailing method for building prototype test skis was to first laminate three layers of mahogany in a curved press. then the tunnel was cut in using a table saw and running the rectangular ski ' blank ' side ways across the saw with fixed guide rails to keep it centered over the crown of the blade. after that a pattern was used to lay out the top profile and after cutting it out on a bandsaw bevels were added with a 45 degree router bit.

 

the whole thing was sealed with lacquer and then they took it to a lake for testing, along with a fistful of files and sandpaper. i was just a kid when i saw some guys from o'brien doing this so i think most of the experts on this that are either retired or dead by now.

[loeweb]

@mwetskier thanks. I'm trying to get a flat spot in the middle of the ski so I'm using 2 separate glue ups and will cut the cove out of the bottom and glue the top to the bottom. Then I plan to cut the bevel on the entire ski. Hopefully I can get it finished.

[BraceMaker]

@mwetskier - interesting about the cross cut, i'd suppose you could render it in CAD and do manual numeric machining where you'd compute out the depth and radius of the bevel at each point linearly along the ski then mark the ski every 1/8 or 1/4" and note the dimension of the bevel.

 

Then you'd cross cut and dial the blade up down and maybe occasionally switch blade sizes, then hand sand to blend the transitions. Man things are easier now ;)

[mwetskier]

i was in a pattern shop in south seattle in the 80s looking into having some cast iron prototypes made for a company I worked for, and the owner was showing me around. At one point I noticed an odd assortment of stuff that looked an awful lot like pieces of a waterski mold.

 

I asked the guy about it and he told me those were initial experiments they did before completing the first mold for the very first fiberglass o'brien. I believe that was the one that had a bright red bottom and sidewalls, a pointed tip, and an inset rubber bumper strip along the top edge of the sidewall that ran all the way around the ski. It looked similar to the red and blue mach 1 ski with the aluminum top skin, but this earlier model had a white fiberglass top with red and blue graphics. the only thing aluminum was the fin.

 

The part i found most interesting was when he showed me what they had used to form the concave tunnel portion of the mold. it was a section of 10 inch heavy wall plastic pipe! yeah, the science of ski design and manufacturing has certainly evolved over the last 4 or 5 decades.

[Chef23]

@mwetskier I bet Kris and Bob Lapoint still have some experience working with files and sandpaper to fix a ski.

[BraceMaker]

@wilecoyote makes sense, I would assume in engineering a combined material structure one would have to be able to account for the material properties through the entire deflection of the combined laminate as there is a zone where the neither of them have failed and both are contributing something.

 

What is the impact of two layers of carbon separated by a heavier glass fabric for instance compared to two layers of carbon not separated and functionally laminated together. Does the one provide additional stability due to the separation or would you consider that to be pointless?

[eleeski]

@wilecoyote Proper selection and application of all the components in a product is Material Science.

 

Carbon is light, strong and stiff. It is (only relatively) weak in compression. I haven't found a good polyester resin to work well with carbon (maybe that caused unforseen problems) so I found a good epoxy. While not cheap, carbon is by no means expensive. When I've done it right, it mixes well with other materials.

 

Glass is reasonably tough, works easily and is widely compatible. High quality glass is almost as expensive as carbon - but a long way from the glass used in a chopper gun.

 

@BraceMaker In my skis, I mixed glass unitdirectional, balsa and carbon unitdirectional to make top stringers to address the weakness of carbon in compression. The glass took the compressive loads and the carbon took the tensile loads. It was a pretty good synergy (but a pain to actually build). It was a way of getting some of the top skin compressive loads to be carried in tension so I didn't have to have lots of the heavy glass or mass quantities of carbon.

 

I now use unitdirectional boron fibers to carry the compressive loads. (As strong in compression as tension and very strong. But, horrible splinters when working with it and it makes carbon look cheap!). Mixes quite well with the carbon.

 

The unitdirectional is just one aspect of the loads on a ski. The other factors like mounting bindings or keeping feet from crushing through dictate different materials (like carbon - even if you want glass stringers).

 

If it doesn't break, I take material out - until it does. Then you know the critical loading and durability spots to reinforce. The learning curve should be fun.

 

When done right, mixing materials is what gives composites their advantages. Hence the name, composite.

 

Eric

[wilecoyote]

@BraceMaker and @eleeski, I think we're all on the same page. We've all worked with these materials, (admittedly I've never used boron, Holy Crap Eric!) and with careful thought and trial and error you can build something pretty good and certainly you can build a ski that will, at minimum match a top end production model but likely exceed it. (from a structural perspective) My point was, and still is, that for a novice, building their first thing ever out of composites, best results will come from sticking to one material. Or, doing a ton of research first. I think both of you guys likely have more experience than I do with composites and for me I was building my boards based on previous failures and hearsay as to which material was best where. My next structure will be very different now I have a better understanding.

 

One video that turned my head a while ago was this, for anyone working with or thinking of working with composites, it's a pretty good watch:

 

 

Chris

[wilecoyote]

And this one speaks directly to my point about mixing materials.

[eleeski]

Interesting video. It reflects the early days when marketing added some graphite into a ski and claimed performance changes. Those changes were real for a run or two but would fade after a couple nasty overloads. But skis and carbon understanding have come a long ways since then.

 

Now, carbon is cheap enough to use it exclusively in the construction. Carbon is excellent in tension and its use there is straightforward. Controlling flex is a bit more challenging but understanding bias plies and skin separation makes it work. Dealing with the compressive weakness of carbon in a real world layup is a lingering problem. That's where clever layups, adding glass or boron becomes an art.

 

Many products are not critically strength limited. Often a well engineered stringer will carry the structural loads. Holding the rest of the product together in place is where a lot of weight can be saved. The video guy's glass fenders might be lighter and cheaper with a glass skeleton for a carbon skin.

 

I mix kevlar in my skis. Not for strength but it makes great spot reinforcement to retain binding screws. It's horrible structurally and impossible to finish (don't sand it!) with the resins I use. I got better results with prepreg but that was an expensive experiment. But the spot mixing of cloth types is easy and really works.

 

Core choice is an entirely new factor - and critical in a ski.

 

Eric

 

 

[usaski1]

Can someone build me a ski? Seriously. I need one 10 inches wide, and about 75-80 inches long... Carbon. If you know skis, and have the resources, lets talk.

 

[eleeski]

@usaski1 The airport fire marshal went on a rampage against anything non aviation stored in our hangars. The Kanski copy mold didn't survive. Probably not a bad thing as the ski that came out of it wasn't magic. So much goes into ski design - and you add variables we can't fathom. 66" is the biggest slalom I can make. And Texas is a long way away for the inevitable tuning. Might be a good project for you!

 

Eric

[Andre]

@usaski1

Curious to see you current stick up close Mark.Is it homemade or is there something commercial out there?

[usaski1]

 

 

 

https://liquidaccess.org/shop/phoenix-ski/

 

@Andre