6oz instead of 22oz

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Bearik
Posts: 2
Joined: Fri Nov 27, 2020 6:05 pm

6oz instead of 22oz

Post by Bearik »

Good day. I am building skis for a snow trike of my own design. (For an example follow link https://shop.hillstrike.com/product/hil ... ke-rev-17/) I'm starting with one ski as a bit of a trial run. The question I have, is, is there any way I can make 6oz fiberglass cloth work instead of something a bit heavier? The skis are going to be 85cm long with a pine core.
If you don't watch where you're going you might wind up someplace else.-Yogi Berra
MarkRebuck
Posts: 1
Joined: Sun Jan 03, 2021 5:12 pm

Re: 6oz instead of 22oz

Post by MarkRebuck »

Disclaimer: My experience comes from building RC models and various other projects over the last 3 decades. I haven't built skis (but that's why I'm on this forum now... I need a project for this winter since I won't be doing any real skiing :-)).

I'm going thru a similar design consideration, because I have a lot of lighter fabric leftover from previous projects.

General thoughts on multiple-light vs. single-heavy layups:

1. Multiple layers allows you to play with the bias a bit, which can be handy. e.g.you do one layer at 0 degrees, and two at 45 degrees.
2. More layers means more work. This can matter if your epoxy/resin has a short pot life and you want to get everything done in one shot.
3. It depends on the specs for each fabric, but I wouldn't be surprised if 3 layers of 6 ounce fabric is as strong as one layer of 22 ounce. Look at http://www.cstsales.com/fiberglass_data.html for instance.
4. Lighter weight fabrics typically have smoother finishes, if that matters.
5. I'm used to doing applications where weight matters and people do extremely dry layups. Making light/dry layups is harder when doing multiple layers, but for skis nobody seems to talk about minimizing the weight of the resin. Folks seem to just slather it on and let the press squeeze out any excess.

Tl;DR: If I had 6 ounce fabric laying around, I would build something with three layers of it (biasing one or two layers at 45 probably) instead of 22 ounce, and see what happens.
Bearik
Posts: 2
Joined: Fri Nov 27, 2020 6:05 pm

Re: 6oz instead of 22oz

Post by Bearik »

Funny. I have a very small amount of fiberglass experience, from RC airplane as well. My dad is into it more. Him and a couple other guys here are building a couple quarter scale DHC Chipmunk from fiberglass. Thanks for the suggestions. I will try that out. Since I'm building three skis and I have material for four I have one I can wreck I guess.
If you don't watch where you're going you might wind up someplace else.-Yogi Berra
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