UHMW is UHMW is UHMW?

[falls]

I am wanting to step up to plastic sidewalls and contacted a local plastic supplier. I initially enquired about ABS plastic, but the thickest sheet they had was 4.5mm. I then asked about the dreaded UHMW.
Questions:
Do you think you have to buy sidewall material from someone like Crown Plastics or will UHMW from a normal plastic supplier do the job?
What is a reasonable price? The quote is for a 2m by 1m sheet for about A$540 (that's as good as $550US for reference). Can get black or "natural". 12mm thick. If I use 10mm per sidewall, with loss from cutting I guess I can expect to get a pair of skis done with 50mm of material width. So 20 pairs from this sheet all going well. That's $27 per pair for UHMW sidewalls. Unfortunately waste a lot of material as general sidewall length is around 170cm, so 30cm on the end unused. Free chopping board with each pair purchased? It seems expensive to me (skibuilders store sells enough 12.75mm thick PTEX for a pair, 60mm wide for US$26), but material costs are high in australia in general.
Any advice/thoughts welcomed
Falls

[MontuckyMadman]

what are you looking to get from plastic that you cant get from wood?
Dampness? Durability? Aesthetics?
Is it worth it?
Most failures in skis that I see happen at this interface, a delamination.
Seems urethane to be a better and more viable option to get all the material characteristics that plastic provides in more bondable form rather than the incredibly inert UHMWPE.
That does sound high.
I think the quality and bondability of these plastics is determined by several factors. The amount of recycled and or virgin material used and of course the process.
If it was all the same, we have thousands of plastics suppliers in the states why choose to get it from crown? Prolly because they offer high quality and multiple color options suited specifically for our purpose.
Perhaps its all smoke and mirrors. I sure dont know.
Crown also provides the service of preprofileing and flame treating for ski and snowboard makers.

why does google think delamination and or bondable are NOT viable words?

[falls]

I guess I have the perception that from a customer's point of view plastic sidewalls are more professional and durable.
Also don't have to epoxy/poly the sidewalls after bevelling.
Also don't have to worry about protective coating coming off sidewalls over time.

Delamination is a mode of failure for composite materials.[1] Modes of failure are also known as 'failure mechanisms'. In laminated materials, repeated cyclic stresses, impact, and so on can cause layers to separate, forming a mica-like structure of separate layers, with significant loss of mechanical toughness

you using google chrome and getting spell check error?

[chrismp]

like MM said, i think you're better off with using PU sidewalls. i pour them myself into a channel that i route into the core blank. very little work to get a seamless and durable sidewall / tipspacer that bonds really well. using the resin is just as easy as working with epoxy. another plus is that you can give your customers a choice of color since it can be pigmented with regular epoxy pigments.
plus it's cheap. i can get 4kg of resin for 40 EUR, which lasts for 8-9 boards (400-450g used per board with sidewalls 8mm thick and 13mm wide).

[Brazen]

Damn Falls, that is just crazy expensive for UHMW. I would check the USPS website and just order the stuff from Crown...I think it would be way less money for you.

[Richuk]

UHMWPE - because the ski techs can fix them with a candle and it allows you to 'show' yourself to be as good as the commercial companies, which only really matters to 'joe' public.

You don't have to buy from Crown, but it would help to know what the specs are for the grade Crown is supplying. I'm guessing it virgin material, but some ski companies are talking about their use of recycled material. Is it worth running a few tests on a few samples to see if local materials will flame treat. Mapp gas appears to be the choice.

Oh, is it cheaper to consider buying it at 10mm thick and cut at 12mm - it certainly saves a % on waste. On the figures you have given you will get 17 sets. With the remaining sheet 100mm x 30 mm, use that as sidewall material for kids skis : )

I would question whether plastic adds anything to you product or does it take away. You using bamboo and doing a great job from what I can see

[skidesmond]

My 2 cents and my IMHO..... When I first started building skis I had a goal to build a ski that looks like a big brand name. You know, flashy graphics etc, plastic tip/tail spacers and plastic side walls. I thought by doing so I would show I was making progress. And it that would be progress in a sense, because my building techniques would have changed drastically as I learned. But then I realized I wanted to build "different" and "simple" (well as simple as ski building can be). So I stuck with wood. Mostly it's what I know, looks great, and simplifies building.

The draw back I'm waiting for is when a customer questions the ski because it has wood sidewalls vs plastic. Wood will require some maintenance over time so it will stay protected. And when the side edges are sharpened you run the risk of taking off the finish on the wood. That may be too much maintenance/worry/work for some people. Owner of commercial skis/boards don't have to think about wiping down their equipment because it's basically all plastic on the outside. So from that stand point a commercial board is virtually maintenance free.

I see a lot of aggravation people go through for plastic sidewalls and it would drive me nuts. Honestly the average or even above average skier/boarder wouldn't know the difference in performance between plastic and wood.

Falls, you're right, it only matters to "Joe" public. And maybe the maintenance is too much for Joe.

[MontuckyMadman]

the renagade from 4frnt is getting rave reviews and is highly coveted by "real" skiers and it has wood sidewalls. If you want to sell to joe public you better make your skis in china.

[bigKam]

About 35% of the skis I make have plastic-type sidewalls; the rest are wood. I try to use really nice and hard wood for the sidewalls, such as Jatoba and others on the upper end of the Janka scale. But keep in mind that these woods will chew up your tools. Anyway, they are expensive but look really clean. For the most part, I rarely treat the wood sidewalls, but I do tell my customers to give it a light pass with fine sandpaper and a quick coat of oil or PU every now and then. Before I send a pair out the door with wood sidewalls, I do treat them for good looks.

Sidewalls don't really contribute much to the dynamic performance of a ski, in my opinion. If you have good data that says otherwise, please share. Overall, it's really the look, so if you pick really nice wood, you can make some really nice skis. I agree that the bonding issue is virtually eliminated by using wood, but as you know, commercial skis mostly sport plastic sidewalls and maybe the average person prefers plastic because there is the possibility that it will hold up better.

But you can make nice skis with wood sidewalls, for sure.

I've been playing around with a lot of different plastics, testing and whatnot. At some point once all the data is ready, I'll share. I use the UHMW stuff from time to time, but I'm very careful about the flame treatment, just to be on the safe side. Because if a delam occurs, water eventually gets into the core and causes other problems. I've witnessed a few of these issues in my own skis, so work hard to avoid them.

Just curious, what are some of the woods you guys are using for sidewalls? I've tried: maple, bamboo, Jatoba, purple heart, hickory, walnut, pine, and fir.

[skidesmond]

MM- I agree. One of the things I hope to accomplish is produce a high quality ski at a fair price and skip all the BS.

Kam - I normally use maple, ash, cherry. Depends what the top sheet will be. I like the contrast in wood color and grain pattern.

[falls]

Mine have all been bamboo sidewall - really just an extension of the core all the way over the edges (wondering if I stick with bamboo sidewall whether I should actually glue them on as a "real" sidewall?)
Even with just a bit of linseed oil or nothing at all the bamboo seems to hold up well. It looks wet when you ski, but dries very quickly. Perhaps a bit of black spotting over time. This last pair I have done 3 coats of a water based polyurethane after masking off the edges and topsheet.
People seem to love telling the story of how the Gotama with bamboo sidewalls all blew out and rotted......
I like the idea of reducing plastic use and the aesthetic of wood sidewalls.

I think this cost I have for a sheet is pretty high. I think crown would be much cheaper. Trouble is dimension from crown plastics - too long and wide for USPS. I reckon though if I sorted out shipping from crown it would prob come in on par or even cheaper than buying locally - I hate that so much...

[MontuckyMadman]

there is no doubt that if you have a wood sidewall ski you cant just leave them in the snow all night or in the car. You have to bring them in and let them dry. Yes, and a treatment once a season is also required. For every 1 gotamas that fell apart there were 10 that didn't. No doubt about that.

We have used maple, ash and even poplar for sidewalls. The poplar doesn't have good impact resistance. the ash seems work work very well.

[Brazen]

Yeah Tim, the dimensions will kill you but the cost for a plank of sidewall is 40 bucks US...I can't imagine shipping would be 500, right?

[MontuckyMadman]

guess again...

[falls]

I got an email from crown about some base material. 100m long at 0.054 thickness. Estimate was 100 pounds. 14 inch by 20 inch by 20 inch box. Too heavy to go USPS (max 70 pounds).
20x20x14 at 70 pounds seems only to offer GXG (global express guaranteed) = $585US

max length for USPS is 46 inches
I have asked a sea freight company for a quote on this box of base material. Will see what it turns up. Had a DHL estimate of $350US for the 100 pound box. the actual material is only costing $220!