Vacuum infusion for ski building, Core Matters and Cold Cure

Bloefeld · Post by **Bloefeld** » Mon Mar 28, 2011 7:49 pm

I have a lot of experience in composites with several patents for industrial applications. I am an ex-ski racer and I am really old.

I have been looking at some of the materials on this site and think it is really interesting and innovative the work that is being done by basic new-comers to composites.

I am un-convinced that the best way to build skis and boards is with unheated presses, and would like to know if anything much has been discussed about vacuum infusion under heat.

This is not a trivial technique, but it is easy enough from what I've seen for most of the sites builders.

I am also completely unconvinced that wood is the best core material available today. I am old enough to remember Hexcel Skis. They were OK skis in their day. However, there have been some incredible advances in the core business segment of composites.

The other big issue that I see is that most folks seem to be using non-heat cured epoxy systems. This greatly reduces the physical properties of any epoxy system.

Am I missing something?

Cheers,

Bloefeld

twizzstyle · Post by **twizzstyle** » Mon Mar 28, 2011 8:56 pm

Greetings! Seems like you could really provide a wealth of information to our humble forum here!

I'd say most folks on here use heated presses with heat-cured epoxies. The biggest driver for folks to do room-temp cures is just that heat blankets and controllers can be very expensive.

Same reasoning goes for wood cores. A few people on here have experimented with other core materials, but wood is (relatively) cheap, and very accessible.

The majority of home-ski-builders try to do it on the cheap, so more advanced techniques don't typically get utilized. In fact, most of the large production ski/snowboard companies use virtually the same techniques most of us have adopted here, which in my mind seems to justify how we do things - although I am sure cost is the biggest driver for the big production guys too.

If you think vacuum infusion is feasible for some of us, I'm all ears! I've done lots with composites as a hobbyist over the years (not just skis), but that's something I've never tried.

OAC · Post by **OAC** » Mon Mar 28, 2011 9:51 pm

I've been thinking of vacuum infusion could be a good thing in this area. But I didn't come to any good conclusion. I remember me coming to the conclusion that the setup would be more complicated than necessary. But it will probably work and the use of epoxy would also be more economic....maybe.

MontuckyMadman · Post by **MontuckyMadman** » Tue Mar 29, 2011 11:28 am

by vacuum infusion do you mean dry layup and then bag and force epoxy through the layup?
Wood is the best IMO because it lasts for so long and has such excellent elongation at break.
Nature has some sweet stuff happening out there.
I have not seen a core material that can take such extreme flexing that doesn't get tired and wear out.
That and the strength to weight ratio is tough to beat.
Thank for the ideas.

skidesmond · Post by **skidesmond** » Tue Mar 29, 2011 2:52 pm

Unheated press is not the best way to make a ski/board... but it's an affordable way and it does work.

I didn't know what vacuum infusion is so, thanks to GOOGLE I found this: http://www.fram.nl/workshop/controlled_ ... on/cvi.htm At least it gave me an idea of what it is.

I don't see how the resin will get pulled into all the layers adequately when the layers are compressed by the vacuum. I can see how it works if you have a mold and you use the vacuum to suck in the resin... like making a boat hull, or a bathtub... etc Can you elaborate?

btw- I had a pair of Hexcel skis, super light but the honeycomb lost their camber after a couple years.

Not to hi-jack your thread but the other day I was researching damping materials and thought I came across something revolutionary. Turns out the material was polyurethane and pvc. A horse trainer found that coating an AL horseshoes with pvc provided a shock absorbing material for the horse and a drastic reduction in injuries to the horse. Sheets of polyurethane maybe useful.....

MontuckyMadman · Post by **MontuckyMadman** » Tue Mar 29, 2011 5:08 pm

pretty sure the dynastar legend pros have either polyurethane or abs or uhmw sheets in the layup.

skidesmond · Post by **skidesmond** » Tue Mar 29, 2011 5:24 pm

HHmmm.... I'll have to find that link again. Maybe do some test with it. I'll pass it on if I find it.

MontuckyMadman · Post by **MontuckyMadman** » Tue Mar 29, 2011 6:21 pm

it was in a pic from a engineering deconstruction of the ski.
It looked like plastic type material. Older legend not the new one we see the vid of.
Maybe it was rubber and I didnt know it.

Richuk · Post by **Richuk** » Wed Mar 30, 2011 3:52 am

I suspect this kind of finish is really quite acceptable

If OAC went into production, supplying pre-cured topsheet, I would buy from him

Richuk · Post by **Richuk** » Wed Mar 30, 2011 3:57 am

I suspect this kind of finish is really quite acceptable

If OAC went into production, supplying pre-cured topsheet, I would buy from him

Bloefeld, I'm assuming you are in the US - so I guess you get the US franchise ; ) Not trying to be a trouble maker, but the results are quite stunning. I'm assuming the process has many other advantages too. Looking forward to seeing your progress!

OAC · Post by **OAC** » Wed Mar 30, 2011 12:07 pm

I suspect this kind of finish is really quite acceptable If OAC went into production, supplying pre-cured topsheet, I would buy from him

Wait and see...

How nice it would be if one could use glass to press against!

Richuk · Post by **Richuk** » Wed Mar 30, 2011 1:52 pm

I'm sending you materials, a big box!

skidesmond · Post by **skidesmond** » Wed Mar 30, 2011 2:09 pm

Here's the link I was referring to earlier:
http://www.earsc.com/HOME/products/Damp ... sp?SID=353

Horse Shoe application: http://www.earsc.com/applications.asp?i ... arentid=43

richie · Post by **richie** » Wed Mar 30, 2011 2:53 pm

I am close to doing my first build of ski's, these are prototypes mainly to test construction methods not on hill performance. My decision was made early on to use Polyurethane sidewalls, rather than UHMWPE. Polyurethane sticks like the proverbial, and also is easily machinable and I believe bonds well with epoxy. In terms of suitability for the purpose, it takes a pounding and is very durable while still being flexible and shock absorbing. Its used in automotive suspension bushes made me think its worth a try and I am pretty sure I've seen boards with Polyurethane sidewalls in the shops last couple of years but never ridden one - maybe its been out there longer that??

So guys , pro's and con's? Whattaya reacon? I'm sure this will get a few good responses.......

skidesmond · Post by **skidesmond** » Wed Mar 30, 2011 4:36 pm

I'd say go for it. Experimenting is what it's all about.

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Vacuum infusion for ski building, Core Matters and Cold Cure

Vacuum infusion for ski building, Core Matters and Cold Cure

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