How are skis made? A 9-episode video series.

Cyrus Schenck

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PRECISE SCIENCE:
Renoun Founder Cyrus Schenck deconstructs a ski into its core elements to give you a behind-the-scenes look into what it takes to make a world-class ski.
We've put together a fun little 9-episode series on the different materials that go into making a ski.

I'll post them here as they come out.

Episode 1
Bases

Bases connect you with the snow and are your first line of defense against a wrong move. They also need to glide smoothly run after run, day after day. Even with this high bar, they still manage to overachieve.

 
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James

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How much worse are clear bases?
(Consider an outfit change next time. It’s creepy, at least on a phone!)
 
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Cyrus Schenck

Cyrus Schenck

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How much worse are clear bases?
Compared to black bases, they are slower and don't hold wax as well and are marginally slower. However, for general skiing purpose (so what 95% of people do) you're not going to notice it. If you're someone who waxes your bases 3-5x a season, sure, you'll notice that the clear bases won't hold wax as well, but unless you're really looking for that last 2-3% performance boost... it won't matter. Shiffrin? Yeah, she wants black.

So, short answer: black bases are better than clear bases but not in a significant manner for general skiing.

Note: other solid colors fall in between. Think of black as the 'best' and clear as the 'worst' with other solid colors being in the middle. Ultimately, you can get colored bases via a variety of methods, such as painting a clear base pink or adding pigments to the plastic before extrusion, so they all can fall on a spectrum. Also, the quality level of a base is going to matter more than the color.
 
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cantunamunch

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So, short answer: black bases are better than clear bases but not in a significant manner for general skiing.

Note: other solid colors fall in between. Think of black as the 'best' and clear as the 'worst' with other solid colors being in the middle. Ultimately, you can get colored bases via a variety of methods, such as painting a clear base pink or adding pigments to the plastic before extrusion, so they all can fall on a spectrum. Also, the quality level of a base is going to matter more than the color.

Have you looked at tearout differences between bases, at all?
 
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Cyrus Schenck

Cyrus Schenck

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Have you looked at tearout differences between bases, at all?
Thicker bases in theory will be better because there's more material (i.e. base) to absorb an impact before it gets to the edge but any perfectly placed rock will take out even the best of edges.
 
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Cyrus Schenck

Cyrus Schenck

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Episode 2
Edges


Hardened steel edges are key to keeping you on track at the mountain—but skis haven't always had them. Fun fact: without edges, we not only lose our ability to carve but also a great deal of the stiffness of the ski.

 
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Tony Warren

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The pigment used to make Black UHMW is carbon black. It has some similarities in morphology to graphite, in that it is a high-aspect ratio material. It is a chemisorbed material with many potential crosslink sites available as part of the UHMW matrix. It is both slick and hard to dislodge from the UHMW matrix. The result is that it is more slippery than virgin white UHMW.

The surface chemistry of the carbon black may improve wax adhesion to it, but I am personally skeptical about the permanence of wax applied to any extruded UHMW. Extruded UHMW does not have any apparent porosity available that large molecular chains found in waxes could penetrate. I have personally conducted scanning electron microscopic examination of virgin white extruded UHMW.

As you point out, sintered UHMW has different characteristics. The number of MOLs per gram of sintered UHMW is significantly lower in sintered products as opposed to extruded UHMW. Sintered UHMW does not have the same level of molecular entanglement and crystallinity as extruded does. Simply put sintering does not have the same properties of extruded UHMW. I have not personally examined sintered UHMW using SEM analysis, but I suspect that it would have some level of porosity that doesn't exist in extruded UHMW.

Sintering UHMW used to be a pretty simple manufacturing method, many manufacturers bought used plywood presses and made good UHMW with them. That seems to be changing and other sintering technologies such as High Velocity Compaction will close the gap between the two methods. This will be great in enabling the use of UHMW in what are essentially injection molded products.

I would encourage you to buy your own untreated rolls of sintered UHMW and contacting Inhance Technologies https://www.inhancetechnologies.com/ to discuss having them fluoro treatment of the plastic for adhesion. The treatment results in adhesion of UHMW to other surfaces that always results in substrate failure and never in adhesive failure. I know, I have run hundreds of adhesion tests to ASTME standards using a wide variety of different plural component adhesives.

The advantage to you, is that the shelf life is no less than 10 years, at significantly less cost. Your process doesn't change at all. As an additional benefit, all coatings adhere to the plastic provided they are polar. Far better decorating without the loss of any physical properties.
 

Tony Warren

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A question for you. Why do manufacturers like you, not use prepreg composites or in the case of metals, adhesive films? In the case of fiberglass, carbon fiber, aramids and other fiber structures, prepregs give far better resin/fiber ratios and with new out of autoclave process, fast turn arounds are possible. In the case of metals, assuming proper surface preparation of the metal, film adhesives are very easy to use and provide excellent results compared to wet laid up products.
 

Dave Petersen

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Episode 3
VDS Rubber


 
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Cyrus Schenck

Cyrus Schenck

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A question for you. Why do manufacturers like you, not use prepreg composites or in the case of metals, adhesive films? In the case of fiberglass, carbon fiber, aramids and other fiber structures, prepregs give far better resin/fiber ratios and with new out of autoclave process, fast turn arounds are possible. In the case of metals, assuming proper surface preparation of the metal, film adhesives are very easy to use and provide excellent results compared to wet laid up products.
Simplicity. I don't know very much about adhesive films for metal (didn't know that was an option in skis) but as for pre-preg, it's alot harder to work with. Everything has to stay frozen and if you have a power outage, your entire supply of glass goes bad. Swapping the entire factory over to this would be a huge undertaking. Not impossible, but our factory has become very good at the wet-layup process. Don't fix it if it aint broke. We've considered bringing on another factory to help offset some of the growth demand which would use pre-preg.... and if we do, we'll need to prototype those models separately which adds another complexity factor.
 

DerKommissar

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Episode 2
Edges


Hardened steel edges are key to keeping you on track at the mountain—but skis haven't always had them. Fun fact: without edges, we not only lose our ability to carve but also a great deal of the stiffness of the ski.

So, I love the honesty you use in your "choosing a ski" blog on your site. In the edge video, you point out that 1.8 mm edges are for weight or cutting costs. I saw that at least the endurance 88 and 98 have the 1.8 edge. Can you talk about that choice in those skis?
 

Tony Warren

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Simplicity. I don't know very much about adhesive films for metal (didn't know that was an option in skis) but as for pre-preg, it's alot harder to work with. Everything has to stay frozen and if you have a power outage, your entire supply of glass goes bad. Swapping the entire factory over to this would be a huge undertaking. Not impossible, but our factory has become very good at the wet-layup process. Don't fix it if it aint broke. We've considered bringing on another factory to help offset some of the growth demand which would use pre-preg.... and if we do, we'll need to prototype those models separately which adds another complexity factor.
In my experience using infusion, wet-layup, rtm, and pre-preg pre-preg gives hands down better products.

At one point, we used a resin impregnator that wet out 102 inch wide triaxial stitched glass 48 oz fabric in two layers for a total of 96 oz. Resin fraction was held at 45 percent, all over a honeycomb core that was complex. We layed up 10 units per shift using 2,000 lbs of resin per day. These were vacuum backed with the appropriate release and bleeder plies. We did a cure heat for about 60 minutes with 10 units in the oven, we then debagged and did a post cure heat for 8 hours.

We switched to prepreg, pioneering out of autoclave prepregs and developed our own b-stage resin package and subcontracted the application of the resin to the glass, with a 25 percent resin fraction. We were able to use our same ovens, and vacuum bagging methods, but had to revise our heat process. We reduced our resin use by more than 50%, but were able to lay-up 20 units per shift, with a much higher quality product.

We installed three large freezers and to prevent loss of power issues, installed stand-by natural gas powered generators. We never had to use them.

Handling the glass was much easier for our workforce. Our prepreg supplier cut our preforms with a laser cutter and we had zero edge fluff to deal with.

Obviously this was done on an industrial scale.

Prepreg in my opinion is a much higher standard of quality than any other method, which is why of course the aerospace guys use it extensively.

I disagree with you about them being hard to work with and labor savings when trimming your skis will easily make up any additional hassle. I am not sure if any large builders use prepregs, but Fischer is a legitimate aerospace composites company and skis are more or less a side-show for them.

I'm sure you make a great product, but the only real change to your factory revolve around building ovens and using vacuum instead of presses to make your skis.

I no longer ski having been forced to quit do to health issues a few years ago after nearly 60 years a skier. When I skied I skied on race room Nordica GS skis and their amazing Doberman pro line. So I do not know a thing about the sort of skis you make.

But I have occasionally thought about making skis to aerospace specifications, then I smack myself upside the head and realize that the building game is best done by people like you.

Thanks for the discussion, I learned a lot.
 

Dave Petersen

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Episode 4
Core


 

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Episode 5
Sidewall


 

Jeronimo

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Episode 2
Edges


Hardened steel edges are key to keeping you on track at the mountain—but skis haven't always had them. Fun fact: without edges, we not only lose our ability to carve but also a great deal of the stiffness of the ski.

Great series Cyrus, love the transparency. We've chatted before (via email) about selection of steels for edges, what is the landscape out there for edges on the modern day ski? Is this one of those items that there are a select few global players that make them and they're essentially standard across the business, or do you have any ability to specify/experiment with grades of steel/hardness/material/etc...? I've always thought it was interesting that DPS skis doesn't even hesitate to list the hardness of their edges (48 HRC) but I've never seen what grades of steel are being utilized.
 

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Episode 6
Tip/Tail


 

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Episode 7
Metal
Premieres July 5 at 5:00 PM


 
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Dave Petersen

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Episode 8
Fiber
Premieres July 9 at 5:30 PM


 

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