My new free tourer

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SleepingAwake
Posts: 123
Joined: Mon Oct 11, 2010 11:06 pm

My new free tourer

Post by SleepingAwake » Sun Jan 29, 2017 10:03 am

Thought i might show my latest ski i finished a couple weeks ago.

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1850mm long, 105mm waist, little bit of tail rocker, long rocker in the front, bit of a pintail. Layup with flax and glass fiber. Balsa/Flax hybrid core.

Jonsn
Posts: 18
Joined: Sat Jan 02, 2016 1:28 pm
Location: Munich & Bregenzerwald/Austria

Post by Jonsn » Mon Jan 30, 2017 10:10 am

Nice skis. Lightweight for these dimensions!

How much resin did you need for the flax? According to the datasheets of flax reinforcements it allways needs a lot resin what prevented me using it so far.

Did you put any reinforcement under the binding area?

SleepingAwake
Posts: 123
Joined: Mon Oct 11, 2010 11:06 pm

Post by SleepingAwake » Tue Jan 31, 2017 12:09 am

Thank you! I'm really pleased about how they turned out. Not perfect by any means, but they don't need to be. And the flex and shape is really dialed in the meantime.

Don't know the amount of resin for the flax alone. But you only need a lot of resin because flax has such a low density, which results in a thicker laminate. But if you look at the stiffness/weight ratio then flax is far superior than glass. And it calms the ski down which is a nice thing while skiing in crappy conditions.

There is a binding reinforcement. A pocket is milled into the core, then a patch of triax glass is placed in the bottom of the pocket, then 5 mm birch plywood. And the depth of the pocket is obviously adjusted so the top of the plywood is flush with the core.

I have a lot of video material which I still would like to edit to short clip of the build process...

gav wa
Posts: 370
Joined: Tue Feb 18, 2014 8:58 pm
Location: Perth

Post by gav wa » Tue Jan 31, 2017 3:49 am

Sweet skis, nice details and finish.
Did you make the cores yourself? I'd be interested in seeing photos of them.

SleepingAwake
Posts: 123
Joined: Mon Oct 11, 2010 11:06 pm

Post by SleepingAwake » Tue Jan 31, 2017 6:04 am

No I used the D200 cores.

Forgot to mention that I made the deck laminate with vacuum infusion and glued it to the core in a separate step. This assures a perfect quality deck laminate with better fiber alignment and a better fiber volume fraction. And you can use a toughened epoxy for the bonding to the core.

Jonsn
Posts: 18
Joined: Sat Jan 02, 2016 1:28 pm
Location: Munich & Bregenzerwald/Austria

Post by Jonsn » Tue Jan 31, 2017 8:35 am

Thank you for the infos.

Good point to use infusion to have less resin in the flax ;)

Just to get it right: You make the laminate above the core (including topsheet?) in a separate step, then glue this piece on the the core, that is already assembled with the base.

Do you do the infusion on a flat surface or e.g. the ski mold to get in the shape of the ski?

SleepingAwake
Posts: 123
Joined: Mon Oct 11, 2010 11:06 pm

Post by SleepingAwake » Tue Jan 31, 2017 8:55 am

Vacuum infusion with topsheet, laminate, peel ply on a flat surface. The whole thing is then glued up with the rest in one step with the lower laminate and base and core and whatnot.

However, if you have a pneumatic ski press on hand you will certainly get a better fiber volume fraction than with the vacuum infusion. A higher void content too, but still very reasonable...

Fvf depends more on the architecture of the fabric than the fiber type. With the stitched biax I use you can reach 50% fvf quite easily.

Hannes
Posts: 83
Joined: Wed Nov 09, 2011 2:20 am
Location: NRW, Germany

Post by Hannes » Fri Feb 03, 2017 8:53 am

Last night I was awake for some time and discused my next build with myself.
Why did you choose the 200 core and not the 250? Just because of the weight?
How did you cut the base? Is it CNCed or just cut with a knife to get the letters in there?

SleepingAwake
Posts: 123
Joined: Mon Oct 11, 2010 11:06 pm

Post by SleepingAwake » Sat Feb 04, 2017 2:18 am

Well, the d200 is the flagship with the best performance and skiability.

And for the base I made a dye cutter to cut out one "F". I basically just cut utility knife blades to length, glued them onto a board using super glue facing with the sharp side away from the board. To give it some more strength I then poured quite a bit of epoxy around it so they are well embedded.
Then I aligned them on the base and used a big clamp to force it down on the table and cutting the shape. Worked amazingly well and there is not the tinyest gap. I will post a picture next time I'm in the Workshop!

Jonsn
Posts: 18
Joined: Sat Jan 02, 2016 1:28 pm
Location: Munich & Bregenzerwald/Austria

Post by Jonsn » Sun Feb 05, 2017 1:13 am

Good idea with the cutter. I am looking forward to seeing the picture!

SleepingAwake
Posts: 123
Joined: Mon Oct 11, 2010 11:06 pm

Post by SleepingAwake » Fri Feb 10, 2017 1:33 am

Ok here is a picture of my dye cutter made from the utility knife blades as mentioned:

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And the result:

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The straight lines are cut with a scalpel which worked nicely, and then the rest with the dye cutter. If I knew it works so well I would have made it pretty...

Pro tip:
1. don't get too impatient and don't put the thing in the oven to cure the epoxy. With the thick layer it will heat up too much and might distort the cutter blades! This happened even tho I used a very slow curing epoxy.
2. cover it well when storing in a dark cupboard. Otherwise there will be blood...

Hope that helps... The videoclip is nearly done btw. Just have to get some clips of the things in use!

Have a good one!

SleepingAwake
Posts: 123
Joined: Mon Oct 11, 2010 11:06 pm

Post by SleepingAwake » Mon Feb 27, 2017 1:23 am

Here is a short clip of the building process, including the vacuum infusion of the deck sheet:

https://youtu.be/o11Q4Iv7LuI

Let me know what you think and if you can think of smarter ways to do things...

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backyardskier
Posts: 139
Joined: Sat Nov 05, 2011 10:26 am

Post by backyardskier » Mon Feb 27, 2017 8:57 am

That homemade drum sander is very cool, never thought about using one for profiling.

SleepingAwake
Posts: 123
Joined: Mon Oct 11, 2010 11:06 pm

Post by SleepingAwake » Mon Feb 27, 2017 10:12 am

It works well with the balsa cores. For denser woods I would probably use a planer for profiling and make the final pass on the sander.

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

Post by pmg » Mon Feb 27, 2017 10:24 am

Hi,

nice to see you work, you obviously like to do things precice :)

How symmetric are the skis? In a freeride like yours it won't matter much but I can think of 3 issues that can cause your skis to end up unsymmetric:

1) The template: You glued a print on the wood, right? if that print isn't 100,00% staight your template will be unsymmetric. My method to make sure the template is to create 2 (using the first as template for the second), flip the second around and again copy-rout both of them.

2) You cut the base straight to the end shape from full material. I (and some others) found a small basewarp happen after this. So I first cut the base a bit wider than needed (+4mm, let it rest and then put it in its final shape.

3) When you glue one edge first to the base completely and then the other (looks like this in the video), you also risk unsymmetry. A lot of people here clamp the base and egdes on the ski template when glueing the edges to the base - this gives pretty good results regarding symmetry.

Cheers
Philipp

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