In the press today - as Swiss as it gets :)

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pmg
Posts: 435
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

In the press today - as Swiss as it gets :)

Post by pmg » Mon Mar 06, 2017 7:51 am

Hi,

some fotos of the skis I put into the press today - hope they come out fine, if they do this will be my future way of building.

Highlights:
- self-routed ski ends made from ABS
- hollow tip
- thin Sidewalls, only 2.5mm thick
- each stringer of the wood core was routed to match the sidecut: Every string is slimmer in the middle equally
- a design austrians will hate :)

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burnside
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Re: In the press today - as Swiss as it gets :)

Post by burnside » Mon Mar 06, 2017 9:58 am

pmg wrote: - each stringer of the wood core was routed to match the sidecut: Every string is slimmer in the middle equally
Do you have more photos that elaborate on this? I'm having a little trouble wrapping my head around it.

Does this replace your usual method of core construction, where you add the final stringers after routing the sidecut?

pmg
Posts: 435
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg » Mon Mar 06, 2017 10:10 am

Hi, unfortunately photos don't really show it, at least not in my bad workshop light.

But yes, I changed my usual method of just "bending" the outer stringers along the sidecut. Now I use the planer jig to have all stringers in the same shape, reproducing the sidecut when glued together.
In this ski, the middle is 90mm wide, the tip 128mm. Its 6 stringers per ski, 4 poplar, 2 ash on the outside.
In the middle, each stringer is 15mm wide, widening towards the tip, reaching a width of 128/6 = 21,3mm.
Then I routed away good 2mm from each side to make space for the sidewalls, also tilting the wood 8°, the same tilt the finished sides will get.

2.5mm sidewalls are really thin, I hope to find 3mm thick material long enough to use in the future. 3mm should suit my needs perfectly.

burnside
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Location: Brooklyn, NY

Post by burnside » Mon Mar 06, 2017 10:18 am

Interesting. Thanks for elaborating.

Can't wait to see the finished product and hear how they ride!

pmg
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Location: Sonthofen

Post by pmg » Mon Mar 06, 2017 1:43 pm

First impression is really really good :)

2 little issues I saw on first glance which don't really bother me:
1) One of my base-in-place-keepers moved a little little bit under the edge and lifted it by maybe 0,2mm -> will be gone after the base grind, if not its the outer side of the ski :)
2)I used 320g/m² glass fibres and 120g/m² white flax fibres below the transparent top sheet. The resin was colored with 5% white. Even now on some places the white isn't perfect, so next time I will paint the backside of the topsheet white, my supplier skibaumarkt.de offers a color specially for that.

Compare these 2 issues with the dream I had the night before layup: I dreamt I forgot the hardener in the resin, noticing it when pulling the skis out of the press... That dream sucked!

Tomorrow I will cut the skis out and finish them expect the base, then there'll be pictures.

Cheers
Philipp

SleepingAwake
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Post by SleepingAwake » Mon Mar 06, 2017 10:00 pm

pmg wrote: Compare these 2 issues with the dream I had the night before layup: I dreamt I forgot the hardener in the resin, noticing it when pulling the skis out of the press... That dream sucked!
Happened to two of my buddies that they mixed hardener GL2 with hardener L instead of resin L, which sucks about equally :)

satch
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Post by satch » Tue Mar 07, 2017 1:32 am

So your sidewall thickness is just 2.5mm? I hope you have found a good way to align your cores.
Still I wonder how you deflash your cores and how you manage to bevel the sidewalls.
Why do you build your cores in such a complicated way?
It seems overly complicated.

pmg
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Location: Sonthofen

Post by pmg » Tue Mar 07, 2017 10:39 am

SleepingAwake wrote: Happened to two of my buddies that they mixed hardener GL2 with hardener L instead of resin L, which sucks about equally :)
Ouch! Could happen here too, have these 2 hardeners here as well. Though I replace L with GL1.

@satch:
I think of how the "perfect" ski would be built like in my opinion and try to get there. In this case, I want thin sidewalls because I just need them for humidity protection. Thick sidewalls add weight, remove quite some wood in the core. And yes, I think I have a good alignment method, tomorrow will prove if I am right or wrong - my girlfriend was ill today, couldn't continue building.

satch
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Post by satch » Tue Mar 07, 2017 11:04 pm

I'm really curious about the outcome!
It looks like you have a full thickness sidewall from tip to tail. Is there a reason you don't use the semi cap construction anymore? Do you still Laminate in two steps? What's you lay up going to be?
Sorry for that many questions, but with your Elaborate plans your asking for it ;-)

mammuth
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Post by mammuth » Wed Mar 08, 2017 2:37 am

You do sublim with vacuum? No problems getting wrinkles in the topsheet?
Tom

pmg
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Post by pmg » Wed Mar 08, 2017 9:31 am

Hi satch, no problem, I will answer gladly (lets be honest, if you post something in the journal section and no one is interested - that sucks!)

I skipped the semi-cap design for one simple reason (and I will soon know if the cap really is the reason for it): When getting colder the cap skis start to have more camber, quite notabe. Another reason is that the 2 press cycle really is additional effort and produces extra waste. And I try to produce as little waste as possible.

And yes, the sidewall is full height, but only 2.5mm thick.

@mammuth: I don't do the sublimation myself.


So I deflashed the ski today, really curious how they turned out. Well, lets be honest: They look great, but they won't last forever because on one side the egde is pretty thin and on the other side the sidewall :)

So really some core shift happened, I still have no Idea how. The interesting thing is that only the middle section moved, which leads me to a theory:
I was afraid of air entrapments under the top sheet when the vacuum pump started to suck. So I tried to "press" the air out by hand, pressing on top if the vacuum sheet. Of course I pressed more in the middle than on tip and tail because thats where the topsheet gets bent over the top edge of the core the most. So maybe my pressure was not only from top but also a but from the side, causing the middle section of the wood core to move a bit.

Also one middle section of the topsheets shifted to the side, no idea how that happened: Tip and Tail are not shifted. You will see it in the photos later.

pmg
Posts: 435
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Location: Sonthofen

Post by pmg » Wed Mar 08, 2017 1:27 pm

Hi,

some photos always help :)


The finished ski: on one the protection film is already removed, colors are nice and bright. On the other one you can see the topsheet shift in the middle... looks a bit strange.
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Here you can see how thin the rest of the sidewall is - wood showing trough... Won't grind the edge often :)
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The white is not perfect despite so much white resin and fibres - will definitely paint the back white next time.
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Same here, a bit of the black carbon showing through on the tips. The hollow tip comes pretty nice.
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Akiwi
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Post by Akiwi » Wed Mar 08, 2017 2:33 pm

Jeez mate.. you have been busy.
I also need to investigate sidewards preasure when using vacuum bagging.
In my last skis where I used thoes nails to center the cores. I was amazed at the dimples that I got in the bases which shouldn't have been possible without loads of sidewards preasure.

I took steps to prevent that too, by introducing a fold in the vacuum bag between the skis, so it baffled me too.

Nearly forgot to add.. Great looking skis.
When are we going to go for a ski together?
I am nobody. Nobody's perfect, so I must be perfect.

pmg
Posts: 435
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg » Wed Mar 08, 2017 2:38 pm

Hi Akiwi,

hopefully soon! I am in Garmisch from 16th - 19th on skiing instructor exams. If you happen to be on the mountain give me a call. Will ride these skis, its my skiing instructors model - a ski for everything.

I used thumb tacks to position the core again, no dimples at all.

satch
Posts: 49
Joined: Wed Mar 28, 2012 5:38 pm

Post by satch » Wed Mar 08, 2017 10:51 pm

Great looking skis! That's a pretty similar layup to what I used in this years free tourer. I just used the heavier UD flax. Up to now I only Hand flexed them and gave them a knock by Hand to hear how they sound. To be honest it sounds pretty much the same as the all carbon ski from last year.
But I don't really mind that. Last years ski work great. And I'm pretty sure that the Wood core plays a much bigger part in terms of dampening
It's a bummer that your positioning didn't work out the way you planned. "Hate to say I told you so" ;-)

Maybe you should use 5mm sidewalls with the next ski. It'll make a ski about 40g heavier but I think it would be worth having that bit room for error.

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