Ski Builders Forum

Was very busy the last few days.
I got some new aluminium to make my mould. This time I used 3mm. Holy cow it is difficult to bend. I was happy my bender was able to handle the weight I had to use.
I also made a new vacuum bag and fittings out of pipe fittings, washers and a cut up bicycle tube to make the washer.
Works perfectly.

Now the wait for the epoxy to cure.
Tomorrow night I'll see how they came out.

Pulled the skis from the press today.
Am pretty stoked with them.


Tried to add a bit off bling, showing off the Carbon tips.
But, I got the HB a bit crooked.
I think I can live with it.. but it will annoy me every time I look at it.



I cut them out tonight.



Camber Rocker came out well.



Next I need to sand them, and clear coat them.

Leiwand!
They look great. Is that .6 mm veneer in top?

Nice Camber/Rocker!

Hannes wrote:Leiwand!
They look great. Is that .6 mm veneer in top?

Yes, 0.6 American Walnut veneer.

pmg wrote:Nice Camber/Rocker!

Thanks. Not sure if I need more Camber in the middle, but then I would have the danger of pushing the tips too far in the air when I step on them and they are pressed flat. I would probably get flappy tips.

Last night I clear coated the Skis and a new Snowboard.
Brings out the grain and colour in the veneer.

Now to take them in for a base grind. Hopefully they can do them before Christmas.

Ooooh Faaaaarrrrrkkk!
I just broke one of my skis!!!
I had it on the radiator for about an hour curing the clearcoat I put on last night and while it was hot, wanted to check the flex. and CRAAAAAK!!!!

I take it that when the epoxy is hot it isn't so strong.



Guess these will have to go in the bin, or just be hang on the wall!!

I guess I can still try them to see how they perform.. but :-(

I'll save the cost of the base grind.

How did you Flex them?
What core material and thickness?
What Areal weight of fibers did you use?

I'm pretty sure that a ski which you can break by Flex testing is probably too weak to be skied anyway.

satch wrote:How did you Flex them?
What core material and thickness?
What Areal weight of fibers did you use?

I'm pretty sure that a ski which you can break by Flex testing is probably too weak to be skied anyway.

Grabbed at the tip, and pushed away from me in the middle.
Core material was Birch Plywood.. so not the most expensive core out there..
Thickness was 3mm at the tip tail, 12 in the middle.
I used 750g/m² Triaxial top and bottom.
Tips had an extra Carbon layer.

the break is well back from where the carbon ended.

I assume it is because the ski was heated, as I flexed it when it was cold, and it was much stiffer.

I would also say I probably will invest more time and money on creating cores from a higher quality wood. I have a load of Ash.

From your photos I'd say that your skis are abut 100mm wide. I would say that a 12mm plywood core with 750g/m² triax on both sides is rather soft. So when flexing the skis you'll easily reach the Point where the top Skin starts buckling.

A couple of weeks ago I made a pretty similar sample to test vacuum Infusion. It had about the same dimensions as your skis regarding width and thickness of the core with 750g triax layers. I flexed the samples after demolding and got the same result. when flexing the sample, the longitudinal fibers of the top layer started buckling.
where did you put the longitudinal fibers? Next to the core or on the outside? My guess is that the second variation wouldn't be as buckling resistant as the first. But up to now it's only a guess. Haven't been able to find anything about that in literature.

satch wrote:From your photos I'd say that your skis are abut 100mm wide. I would say that a 12mm plywood core with 750g/m² triax on both sides is rather soft. So when flexing the skis you'll easily reach the Point where the top Skin starts buckling.

A couple of weeks ago I made a pretty similar sample to test vacuum Infusion. It had about the same dimensions as your skis regarding width and thickness of the core with 750g triax layers. I flexed the samples after demolding and got the same result. when flexing the sample, the longitudinal fibers of the top layer started buckling.
where did you put the longitudinal fibers? Next to the core or on the outside? My guess is that the second variation wouldn't be as buckling resistant as the first. But up to now it's only a guess. Haven't been able to find anything about that in literature.

The ski dimensions are 136 / 94 / 122, so pretty close to 100.
I also didn't pay attention to if the longitudional fibres of my triax were against the core, or away from it.
Thinking about it I agree that having them away from the core should add a bit of stiffness to the skis.
As I can detect a bit of a cross pattern under the veneer, I am pretty sure the Longitudinal fibres are against my core.
I've decided to toss these, or hang them on the wall and put it down to a learning experience. I have enough materials for another set, so I'll start building the cores tonight, then I have Friday night to start building a new pair, and if I am lucky should get them in the press in the weekend. The hard work with the profile table, mould and ski template are all done.
Maybe I should use my own suggestion to someone else here on the forum to drill a bunch of holes in the skis and use it as a Schnaps / shot tray. (Problem is I hate Schnaps!)
I am going to do a full Ash core.
Does anyone else think that one layer of 750g/m² triax on either side of the core with a 0.6mm Veneer top layer is not enough?
I could add a layer of 440g/m² Unidirektional to the bottom also. Or would this be too stiff?

Well, depends on what kind of skis you like to ride. For me it would be too soft, I like hard planks.

If you want to put extra longi stiffness in there I think its better to put even amounts on top and below the core, otherwise camber/rocker might change. You can get Uni stuff in almost every weight you want.

Cheers

And is the whole ski broken or just the veneer?

pmg wrote:And is the whole ski broken or just the veneer?

That is a good question. It could be just the veneer, but I suspect it is more as it has a bit of a permanent bend.