b2therye's ski's

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falls
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Joined: Tue Oct 27, 2009 5:04 pm
Location: Wangaratta, Australia

Post by falls »

maybe heating them up caused trapped air to expand and started the blisters?
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gozaimaas
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Location: Nagano Japan

Post by gozaimaas »

Sounds like you had voids there and the heat turned them into bubbles. Cut slits and fill with epoxy.
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b2therye
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Location: Sydney, AU

Post by b2therye »

Update.

when i took them off the mold i didn't notice these blisters, i noticed them after heat treatment and the vacuum wasn't the best when molding.

heres one of the blisters:

Image

used a 1.5mm drill bit to drill some holes in the base:

Image

then a 10ml syringe and an 18 gauge hypodermic needle

Image

some clamps and blocks of melamine

Image

and hey presto, flat again!

Image

took them to the local ski shop for a good base grind. the guy there was really excited about them when i told him i made them myself. feels pretty good for someone to be excited about them.

just got to bevel the sidewalls, mount the bindings and coat in some clear.
gav wa
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Location: Perth

Post by gav wa »

What is the temp just above the surface of the ski during your heat treatment? What are you trying to achieve with the heat treatment too?
Those blisters look burnt in those pictures?
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b2therye
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Post by b2therye »

i tried to get 80ºC on the skis but one of the lamps dropped and scortched the top surface of the ski.

the heat lamps were only one the top surface.

the epoxy manufacturer recommended heat treatment of the epoxy after the epoxy has its initial cure at room temperature.

this heat treatment is designed to help the epoxy fully cure as there is no heat applied during molding.
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falls
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Post by falls »

Which epoxy did you use? Kinetix?
Post curing will improve the properties of the epoxy but if you cure under vacuum for a decent time (eg 12 hours) at at least 20C then you prob get a decent cure.
Where did you get the skis ground? Did they do a good job on a pair freshly pressed?
Don't wait up, I'm off to kill Summer....
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b2therye
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Post by b2therye »

Hey falls, I used Hexion L285 (EPIKOTETM Resin MGS® L 285)

This recommends 24 hr cure @ room temp then heat treatment of between 50 and 80ºC

http://ironbarkcomposites.com.au/images ... 160306.pdf

we'll have to see how they go with grinding them, they had a brand new ski grinding machine and the guys there were so stoked bout the skis i'm sure they'll take care of them. they said they'd do them either today or tomorrow.

i wouldn't mind looking at alternate epoxies, what do you use and who do you get it from?
sammer
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Post by sammer »

What I read from both the link you posted and the manufacturers site was...

"If high heat resistance or aircraft approval are not necessary, hardener 285 can also be
used without heat treatment afterwards. However, the indicated properties will only be
obtained after heat treatment at temperatures over 50 °C (122 °F)."

I would pass on the heat treatment. Just leave em in a warm room for a few days or so before you cut them out.

My bet with the blisters is voids in the layup and not enough pressure.
Then your heat cure or belt sanding caused the base to expand and bubble.

I've used the same method for repairing blisters but drilled a few holes so I knew the pocket was full.
Drill around the outside then inject epoxy in the middle until it comes out the outer holes.

Post some pics of the final base after the grind.

sam
You don't even have a legit signature, nothing to reveal who you are and what you do...

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b2therye
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Post by b2therye »

Yeah, I was considering skipping the heat treatment but I went on the side of caution as the epoxy may not cure completely without heat treatment.

the blisters are definitely voids from not enough pressure, several reasons for it but I'll definitely have better vacuum next time.

I drilled at least 2 holes in each blister (it doesn't show on the photo) so I would have some indication that the blister was full.

Will do, I'll pick them up on the weekend.
gav wa
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Post by gav wa »

Did they grind up all good?
I guess that's the main thing eh.

Photos mate, photos :)
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falls
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Post by falls »

I might pass on the heat treatment or create an indirect method of heating (eg. a box filled with hot air) rather than the one sided direct heat globe method.

People here in Aus have used :
Sicomin Sr8500/SZ8525 from lavender (http://www.lavender-ce.com/) - gozaimas I think and that's what I use. It is ski/board specific, but requires 80C primary cure. The lavender guys are easy to deal with in my experience.
Otherwise have used west system - ok but not the best - room temp cure OK (as long as around 25C - harder in winter to get good cure). Available everywhere (or from ATL composites). ATL also have the kinetix range which I have also used and blueroof uses I think. IT is room temp cure but can be post cured at 30-80C for vayring periods.
Bioresins from entropy are available in aus now too - http://www.surfinggreen.com.au/?product ... er-sap-clr or other sites on google search. Just confirm with the other guys on the forum which one they use - I think may be CLR but possibly could be another of their resins. I think entropy resins go better with heated primary cure.
Don't wait up, I'm off to kill Summer....
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falls
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Post by falls »

http://www.samsarasurfboards.com/E17673 ... er-Sap-CCR
Might actually be this super sap 100/1000 but ask the others who use it - vinman?
Don't wait up, I'm off to kill Summer....
gozaimaas
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Post by gozaimaas »

Yeah I use sicomin and its fantastic but you must have heat mats. Also its $100 dangerous goods freight from bris to syd.
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b2therye
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Post by b2therye »

I could use sicomin if i got a silicone vacuum bag.

did you make your heat blankets or buy them?

Also i'm finding it hard to source a bevelled router bit for the sidewalls...

which kinetix did you use falls? R104? was it any good?
gav wa
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Location: Perth

Post by gav wa »

Hey mate, I'm new to all this too and am in the process of making my own heat mats. I have already made a small test blanket and it works awesome, was a piece of cake too.
About $30 of fiberglass, $120 for silicon and $30 for a 94 meter roll of nichrome wire. That gives me enough for two blankets.
Heaps of guys here know heaps about them and have made heaps of them so go for it.

I bought two PIDs and SSRs too but I already think I didn't really need to, the dimmer like chrismp uses looks like a good cheaper idea or I even saw 3000 watt voltage regulators on ebay for $10 each from china, although I don't know if anybody has tried this way yet, you could be the first :)
The DIY heat mat thread has all the info you need.
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