HB (Hansen Boards)

Document your personal work here. Show photos, movies, and share your secrets.

Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp

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Akiwi
Posts: 370
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Location: Olching (Near Munich) Germany

Post by Akiwi » Thu Jan 19, 2017 7:53 am

chrismp wrote:Nice skis! What thread did I miss regarding the skibuilders get together?! I will be at Hochkönig this weekend. Any chance the meeting is there?
Hi Chris, the get together is organised by Georg from Skibaumarkt.de.
We will be in Der Tauplitz in Steiermark. Meetig between 8:30 and 9:00 on Saturday. Details on the website.
It's Much closer to Vienna than Hochkönig!! ;-)
I am nobody. Nobody's perfect, so I must be perfect.

Jonsn
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Location: Munich & Bregenzerwald/Austria

Post by Jonsn » Thu Jan 19, 2017 9:07 am

Nice skis Akiwi.

I built very similiar ones as well. Used 2.5 mm balsa for the thin parts. Used the laser cutter at Makerspace in Garching/Munich to cut them out. Unfortunately the core shifted a bit and I have some Balsa exposed after flashing. How smaller is you core compared to base with edges?

I will post some pictures as soon as I have enough posts.

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Akiwi
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Location: Olching (Near Munich) Germany

Post by Akiwi » Thu Jan 19, 2017 10:00 am

Jonsn wrote:Nice skis Akiwi.

I built very similiar ones as well. Used 2.5 mm balsa for the thin parts. Used the laser cutter at Makerspace in Garching/Munich to cut them out. Unfortunately the core shifted a bit and I have some Balsa exposed after flashing. How smaller is you core compared to base with edges?

I will post some pictures as soon as I have enough posts.
2mm a little more on the tip and tail.
I used the same template as I used for the bases without the edges.
I am nobody. Nobody's perfect, so I must be perfect.

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

Post by satch » Thu Jan 19, 2017 11:42 pm

Thanks for your answer!
I'm surprised your blade was able to deflash more than one ski. The Wood blade I used would not be able to cut that much fibers. Maybe I should give it another try.

chrislandy
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Post by chrislandy » Fri Jan 20, 2017 4:28 am

Akiwi wrote: Hi Chrislandy, When do you do that with the APF7? After the layup and before clear coating with time for it to dry?
yep, before clear coat think of it as a invisible pinhole filler ;) as it blends into the carbon. wait for it to cure then clear coat

mammuth
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Post by mammuth » Fri Jan 20, 2017 6:42 am

satch wrote:You can Transfer a printed image onto wood using acrylic gels.
Pls can you elaborate, sounds interesting
Tom

satch
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Post by satch » Sat Jan 21, 2017 12:36 am

https://m.youtube.com/watch?v=kMcgJOW7b1A

This video should explain it. I have never tried one of these transfers gels but seen results with photos and they were pretty good. You can also use acetone or paint thinner but the results are not as clean.

Dtrain
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Location: Prince Rupert/Terrace B.C.

Post by Dtrain » Sat Jan 21, 2017 7:04 pm

nice work on that profile table

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Akiwi
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Location: Olching (Near Munich) Germany

Post by Akiwi » Sun Jan 22, 2017 12:12 pm

I broke one:

Image

Was with some amazing skiers at the Skibuilders meeting on Saturday, and I broke one.
We were off piste at the top of the mountain skiing through the windblown waves, and suddenly I heard "Crack"
Looked down and there was a crack in my right ski.
I had to ski 1.5 hours back to my car with the broken ski.
Luckily I had a second pair with me.
I was also not 100% happy with the result, so I am not too upset.

Live and learn I hope.
Image

I see that the break was where I drilled and 8mm hole through the core and used a dubel to center the core on the base. probably wasn't the best place to do that.
I am nobody. Nobody's perfect, so I must be perfect.

satch
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Post by satch » Sun Jan 22, 2017 10:51 pm

Even if you didn't like the way it skied, it's always a pity if they fail.
Perhaps you shouldn't taper the core as much. For your next pair i Would recommend to widen the middle part of the core. The way you did it there is a pretty big difference in stiffness right in front of your bindings!

chrislandy
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Post by chrislandy » Mon Jan 23, 2017 1:40 am

I'd move the taper forward about an inch past where you cracked it, yes that may have been a weak point because of the plug but that looks like bending failure rather than core shear failure, so basically the compression side (top face) exceeded it's limit debonded and buckled.

I was going to say just basic bending failure of the compression "flange" but unless you changed the layup in that last inch or so then it would have failed probably a bit closer to taper

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Akiwi
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Post by Akiwi » Mon Jan 23, 2017 2:42 am

Yes, I intend to do a more gentle taper , and I will run an Ash stringer the full length of the ski with Paulownia left and right for lightness... and do without the plugs, or put the plug in the widest part of the ski.
I am nobody. Nobody's perfect, so I must be perfect.

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vinman
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Post by vinman » Mon Jan 23, 2017 8:49 am

I went back and looked at the pic of your cores. The finger joint in your core is right at the spot they broke.

A couple things I'd change
1. If you finger joint, make sure this does not terminate right at the binding.
2. Definitely make your mounting area not taper as quickly.
3. Possibly make your composite stronger and it add a second layer of lighter fiberglass under the binding mount that extends several inches past where your screws will be. Taper this binding may to a point for that it kind of "feathers" out the flex a bit and doesn't create a point in your laminate that is just suddenly stiffer.
4 if you use a dowel for base/core alignment don't put it anywhere near your bindings.
Fighting gravity on a daily basis
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Akiwi
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Location: Olching (Near Munich) Germany

Post by Akiwi » Mon Jan 23, 2017 12:29 pm

Thanks for the good tips.
1. The break is actually in front of the finger joint.
2. I will taper further along the ski, and run one piece of Ash, 2cm wide from tip to tail.
3. Good idea with the extra layer around the binding area. I will do that.
4. I'll try to do without the dowel completely. And if I use one I'll get some thinner 6mm ones. Is also easier to get the fiberglass around them.
I am nobody. Nobody's perfect, so I must be perfect.

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chrismp
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Post by chrismp » Tue Jan 24, 2017 12:51 am

Akiwi wrote:1. The break is actually in front of the finger joint.
Afaik finger joints themselves are not the weak parts...in fact the wood usually fails before the glue joint does. You can think of the glue joint like a knot in the wood that is harder to break, so the softer wood surrounding it is what gives way under load.
Last edited by chrismp on Tue Jan 24, 2017 1:14 pm, edited 1 time in total.

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