Twizz 2011/2012
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- Location: Kenmore, Wa USA
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They look nice twizz. I like the green base and sidewall. The bamboo veneer looks sweet too.
Fighting gravity on a daily basis
www.Whiteroomcustomskis.com
www.Whiteroomcustomskis.com
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So after doing this for a couple of years, I had my first catastrophic failure of a home-built ski.
Landed WAY backseat off of a big drop at Hyak today, had a bit of a spill. Got back on the lift, then Kevin pointed out that my top sheet looked a little funny. Upon closer inspection we saw this...
Of course, the conditions were way too good to give up, so I kept skiing for another ~2 hours or so, this ski was just VERY soft in the tail
Now the mode of failure was actually the bamboo core that broke, not a real delamination of layers. The bamboo I used for these skis was a little different than the normal stuff I use. They were flooring boards like usual, but had a middle layer of bamboo with the grain running laterally instead of longitudinally. If you can imagine the profiled core, in the center of the ski where it's thickest, the bamboo fibers are longitudinal... as it gets thinner, you get to the middle layer with lateral fibers... then as it gets thinnest towards the tips, it's back to longitudinal fibers. The failure happened where the fibers are lateral, I think it's kind of crappy bamboo, the grain is very loose, and it just tore. Lesson learned, don't use that bamboo!
Only got 3 days on these skis, and they've been epic, so I've got to make a new pair as quickly as I can. Nothing wrong with excuses to make more skis!
Landed WAY backseat off of a big drop at Hyak today, had a bit of a spill. Got back on the lift, then Kevin pointed out that my top sheet looked a little funny. Upon closer inspection we saw this...
Of course, the conditions were way too good to give up, so I kept skiing for another ~2 hours or so, this ski was just VERY soft in the tail
Now the mode of failure was actually the bamboo core that broke, not a real delamination of layers. The bamboo I used for these skis was a little different than the normal stuff I use. They were flooring boards like usual, but had a middle layer of bamboo with the grain running laterally instead of longitudinally. If you can imagine the profiled core, in the center of the ski where it's thickest, the bamboo fibers are longitudinal... as it gets thinner, you get to the middle layer with lateral fibers... then as it gets thinnest towards the tips, it's back to longitudinal fibers. The failure happened where the fibers are lateral, I think it's kind of crappy bamboo, the grain is very loose, and it just tore. Lesson learned, don't use that bamboo!
Only got 3 days on these skis, and they've been epic, so I've got to make a new pair as quickly as I can. Nothing wrong with excuses to make more skis!
Ya know since I started hanging out here that's the first broken ski that I can remember.
Shouldn't be too hard to build another with a better quality core.
I think you have a bit of a quiver to keep you skiing in the meantime
sam
Shouldn't be too hard to build another with a better quality core.
I think you have a bit of a quiver to keep you skiing in the meantime
sam
You don't even have a legit signature, nothing to reveal who you are and what you do...
Best of luck to you. (uneva)
Best of luck to you. (uneva)
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Yes. They were flooring boards, but they had a middle layer with the fibers running laterally. The middle layer also seemed to be a very loose grain, almost like it was crap bamboo and that's why they used it as a core. I should have known better...Sherpa Burns wrote:So, were you using the bamboo ply that is the 3 layer cross laminated stuff?
Picked up more bamboo yesterday, the plan is to make another pair identical to these. I've still got some of the green sidewall left too
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HAHAHAHAHAHrockaukum wrote:An thus the "invention" of rocker.
ra
Did a little work today and yesterday after skiing... got the cores cutout for the replacements for the broken skis, tomorrow I'll epoxy on the sidewalls.
I'm working on a new all-mountain ski - I basically took the last bamboo-veneer skis I did, and made the tip and tail wider. Looks like an awesome ski! I got the cores cut out and epoxied the sidewalls on tonight. Thinking I might be ready to press a couple of skis next weekend.
What epoxy do you use to attach your sidewalls? Do you heat cure this? If so how do you clamp it and do the clamps get in the way of the heat blankets?
I've been thinking about using epoxy instead of PU glue but the lonny cure times and the clamps being in the way of the blankets have deterred me. I was thinking of building a full length sidewall clamp jig thing but haven't had the motivation since I'm not actively building during ski season.
I've been thinking about using epoxy instead of PU glue but the lonny cure times and the clamps being in the way of the blankets have deterred me. I was thinking of building a full length sidewall clamp jig thing but haven't had the motivation since I'm not actively building during ski season.
Fighting gravity on a daily basis
www.Whiteroomcustomskis.com
www.Whiteroomcustomskis.com
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- Joined: Tue Mar 07, 2006 8:25 pm
- Location: Kenmore, Wa USA
Yep, I'd love to use the heat blanket, but the clamps get in the way
I use the same epoxy I do for the layup (using supersap for this pair), and once it's clamped up I use a heat gun to get things nice and warm. After 24 hours it's cured enough to take the clamps off (at least this worked the last few times I did it... I'll see this evening if it worked). Then I'll remove the clamps and lay it on the heat blanket at a low heat (something like 130deg F) to post-cure it a little more. I'm not too worried about it being completely cured, that can happen during the layup, as long as it holds well enough for profiling (which it never does)
I use the same epoxy I do for the layup (using supersap for this pair), and once it's clamped up I use a heat gun to get things nice and warm. After 24 hours it's cured enough to take the clamps off (at least this worked the last few times I did it... I'll see this evening if it worked). Then I'll remove the clamps and lay it on the heat blanket at a low heat (something like 130deg F) to post-cure it a little more. I'm not too worried about it being completely cured, that can happen during the layup, as long as it holds well enough for profiling (which it never does)