:: View topic - bamboo stringers

ninthward has skis with a bamboo stringer instead of carbon but wiuld bamboo give you the flex you need? if so how thick?

I've been playing around with some super seekrit skunk works ideas, can't tell or I'd have to kill you and all, or get laughed at

but...

Can anyone think of any issues with doing some laminating and then doing a seond pressing for, say base and topsheet? I can't think of anything, but I could be missing something obvious.

Part of it is because my "non-standard" layup ideas the option of adding composite if I end up with a too-soft ski (based on the oh so scientific flex it with your hands test) appeals to me.

I know that Option snowboards uses pre-cured fiberglass. This glass is cured under tension and pressure as a seperate peice. The cured glass is then used to build the snowboard. The bonus with precured glass is that you can use the top layer of glass as the topsheet.

Is this what you are thinking about?

That's not exactly what I was thinking, though it does sound interesting...

I was wondering if anyone can think of any issues with pressing the glass-core-glass part of the ski, and then pressing the topsheet and base in a second pressing. The only thing I can think of is aligning the base to the core correctly, but I think I have a way to make sure that works.

Maybe a better way to describe what I'm thinking about is adding composites to the core (which requires using the press) and then doing a regular pressing.

One thing that you might have to watch out for is that epoxy usually does not bond well with cured epoxy. You can either do your multiple layups before it fully cures or sand it before adding the additional layers.

kelvin

Instead of sanding (which may damage the laminate) you can use a special fabric (don't know the english word for it - a translation may be "tear off fabric"). It doesn't bond with the epoxy and can be easily removed from the cured laminate leaving a very rough surface that bonds perfectly.

I used this for my first ski because to make it possible to add some more layers later. Which i actually did with the carbon UD strips and the top layer.

peelply?

After 4 months on the project, I am getting very close to layup. To date, I have build all required tools for the job, laminated cores, bent edges, created base template and own all materials to move forward. I am hoping to press by the end of the month and get some days on them in March when there's good base and it typically snow in Maine/NH.

My questions are:

1) For those with West System experience, how many metering plunges of West Systems are you using to:

a) Wet base?

b) Wet 22oz glass?

c) Wet core, and do you look for absorbtion?

2) I will be pressing in a 60 - 65 degree basment, will 12 hours suffice in the press?

3) You don't flame prepare your bases do you?

I appreciate any help you can afford.

I did not use west epoxy but I would suggest only mixing a bit at a time, no more than 3 or 4 plunges, just go back for more. The reason for this is that in the container if the glue starts to go off it gets out of control. If it is on the ski it is spread out so it does not get hot.

When wetting out wet the base out then lay the glass on and try and squeeze the epoxy up from the bottom and then soak the top. It does not have to be thick and it is pretty obvious when the glass is wetted out. I use a flexible scaper to spread the epoxy.

In order to check your set time just glue some pieces of scrap wood together and set them near your mold. That way you can try and break them apart at various times and once you find the samples are glued you can release pressure on the mold

Are you using fast or slow hardener, I found that working by myself it took almost 1.5hours from the time I started until the ski was in the press and you don't want to have the cure start to early. I used medium speed MAS epoxy and vacuumed for 10 hours in a cool basement but I did have a radiant heater shining down on the mold assembly making it just warm to the touch.

I did not flame treat the base as this was already done by durasurf.

Good luck, Tony

Personally I would not depend on the pumps. The last time I used them the hardener pump would always have a bubble in the chamber. When I started weighing the parts I had a .10 oz error on the light side for the hardener.

I also found that I had way more waste when I used the pumps, because I was stuck with the pump ratios and had to mix 1 1/2 oz. at a min. (the last set of pumps from Raka would only do a 3 oz. batch min.) There was always too much resin mixed for the job.

When I started using the scale I had a better/more accurate mix ratio and less waste. Even if you just used one of those calorie counter scales from the local market, which I had to do once) you would be better off than using the pumps IMO. Try to find one that measures in grams and oz.

I can't help with amounts, but I did see measurements that the Kams have used. If you do a search you should be able to get a good idea of how much you will need per ski, and what tonyt said about mixing small amounts is a good ideas. It will take a couple of tries to get the amounts for each ski right. In most cases you could mix up some for the base and first layer of glass. Then mix more for the core and next layer of glass. You will have plenty of working time to do this.

If I understand some things I have read right you could mix the same amount of epoxy as the glass weighs + some for the base wet out. That would set you up for a 50-50 ratio glass to epoxy by weight in the composite.

Good luck. If this is first time you've used epoxies be sure to read the directions well and mix completely. Its very critical to mix completely or the final product will have problems.

Hafte