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For discussions related to ski/snowboard construction/design methods and techniques.

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MontuckyMadman
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Joined: Fri Jun 20, 2008 9:41 pm

Post by MontuckyMadman »

9 oz in a uni carbon in a 12k is super stiff.
Weird you wiuld need that above and below unless the ski is super narrow, like 70mm underfoot.
I think maybe you are iust overgrinding.
Have you done a few 100 grit passes to get the epoxy off then send then to a shop to do final grind, bevel and stone? You could be distorting the ski by pressing too hard when grinding.
Base high is perhaps just over rabbitl with such a beefy cadbon. Maybe this carbon is the issue. Try a 5oz uni.
Those metal plenum based grinders are not ideal. Everything now uses a rubber contact wheel. No more steel plenum.

Tc = thermocouple
sammer wrote: I'm still a tang on top guy.
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skimann20
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Post by skimann20 »

Next round of testing. everything the same but used the cassette and a .4mm and .80mm rabbet.

.4mm rabbet
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.8 rabbet
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both after light grind: .4 on L .8 on R. (.4 slipped out of my and and took a ride to the back of the grinder:
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0.4 this is with no pressure (slight pressure ski is very flat)
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0.8 this is with no pressure (slight pressure ski is very flat)
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0.4
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0.8
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So at this point I have found nothing as to why my full length skis are coming out base high. Its obvious from these test pieces that individual pieced on their own are fully capable of being flat. so what else: tip spacer affecting them this much... I doubt it. the middle2/3s of my skis come out real flat. I only see this in the tip and tails so that would still point me to not good compression in those areas if the middle section of my ski is not effected right? Do i remember someone putting strips of wood between the bladder and cat track at some point to increase pressure in these areas? thoughts?
skidesmond
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Post by skidesmond »

I put strips of 3 - 3mm hard board in the tip/tail sections of the press between the bladder and the top form. That gives me added pressure in that area. Other things I do is base grind with 80 grit, only 2-3 passes to get off the resin and get more/less flat. I may have to concentrate in a couple areas. I don't apply too much pressure when I'm grinding. Then switch to 120 belt and grind tip/tail maybe 3-6 times. Then concentrate on any areas that need it which is usually the tip/tail.

btw I don't rabbet the core. I use a "filler".
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vinman
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Post by vinman »

either not enough pressure or you have some irregularities in your molds or perhaps both.

I've shimmed under my top mold.over the cat track so that I get better mold conformity. I have some thick rubber matting I came across that works really nicely.

I pull my ski hot at about 140, cool them on their side to just above room temp and then flash them out.

I have to do a bit of extra grinding in the tip and tail sometimes but nothing too crazy. I use the 80 grit belt initially then use a worn 80 grit to take the hairs down a little before going over to the stone for a few passes.
Fighting gravity on a daily basis
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mammuth
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Post by mammuth »

Check if your press clamps tip and tail areas too early, means before the center is pushed down fully. Could be part of the problem
Tom
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skimann20
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Post by skimann20 »

vinman wrote:either not enough pressure or you have some irregularities in your molds or perhaps both..
First thing I checked (irregularities) three different times.

Skidesmond: do you have a pic of this set up?

Mammuth: interesting thoughts. i feel fairly certain that the middle engages before the tips and tails press out.
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