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Hi!

Finally I have all the materials I need to build a ski. Thanks to all of you that helped me!

Now I started to build the press. A vacuum press is too expensive for me. I'm going to build a press of wood with 10 threaded bolts on each side. I hope that works.

I have some air-dried ash shelves. do I have to build the ski out of strips? The problem is, if i cut them into strips, i will not have enough material! The ski will not be wide enough.

I already have a name for my skies:

"You'll never find friends with salad."

It's a quote of a Simpsons episode.

karsten

I like the wood press, but I suppose you must really design it carefully, to be sure to have a uniform and sufficient pressure along the whole ski. I did some trails oressing longboards.

I would use three rows of bolts (10 or more per row) to press a pair of skis.

Maybe I will send you some drawings.

hmm i don't think that vacuum presses are expensive and its easier tio build

i payed 0$ for it

the press don't need to be that robust as if your use a fire-hose press so its enough if you use about 5 ribs of wood and one sheet of plywood over the ribs

I have been thinking about making a pair of skis without cutting strips for the core. I am curious how they would turn out. As for the ash, I have a couple cores set up that are made of ash, and they are really stiff and pretty springy (which is a good thing). One thing you might do if you make solid cores, is to use extra layers of fiberglass. This would give you a little extra strength. The only worry I would have about a solid core is that it might warp significantly when you profile the core. But then again, it is hard to tell how a piece of wood will move around when it is shaped.

the press is nearly done.

i'd like to insert a pic... how does that work?

check out my photos:

http://www.stud.uni-karlsruhe.de/~uryo/karsten/

In the middle i used a plastik plate. every 10cm there are two threaded bolts (8mm). at the ends of the press i will use the cut-out from the lower part of the press.

I wanted to use the whole cut-out, but i think its very difficult to make it accurately, because the thickness of the ski varies.

I hope that you understand what i want to say....

Do you think it could work like that?

It looks nice. I suppose it should work.

Maybe just do some tests, like laminating some glass on a wood board, to be sure that you manage the whole process.

It is very nice that you are trying something different.

Good luck.

i think it may work. maybe try using a torque wrench to get all the nuts tightened down somewhat uniformly? how do you plan on pressing the tip and tail sections? i like the simplicity of the press.

thanks for your feedback! now i am more confident.

@ littleKam: i think its a great idea with the torque wrench!

I will continue with the press in a few weeks after returning from france (les Arcs) :-P

then i will show you the whole press with the tip and tail section. i tried to explain it, but it seams to be too difficult...

cu in a few weeks!

karsten

My press is ready!

But building the ski takes a lot of time. An i have several problems:

1. How can I bend the edges, so that they fit EXACTLY to the base?

I put the ends of the edges into our fireplace and they started to glow. Check out a picture (its not exactly!!) http://www.stud.uni-karlsruhe.de/~uryo/karsten/04%20base%20with%20edge.JPG

2. Before I cut the base, I taped it with double-side tape at the template. Afterwards, it was very difficult to take off the tape! Next time I will use another one. With which kind of cleaner can I clean the base from the rest of the glue?

3. My old planer broke! The bearing became to hot... damn.

more pictures:

http://www.stud.uni-karlsruhe.de/~uryo/karsten/

rock on,

karsten

I hope you dont try to press the skis with the base turned the way it is on picture 4. The rough side is the one treated for bonding to epoxy.

are the sides really different? i thought bouth sides would be the same. thank you for the hint!

I sold you the base, right? That one has both sides rough. so it does not matter which side you put up.

Where are you building the skis? I will visit a friend in Koeln next week (Karneval...), so I can maybe come to have a look at your skis...

hi davide!

i'm building the skis in Ulm. but next week i will go skiing in austria.

How did you bend the edges?

Usually I do not put edges at tip and tail.

Here I flame treated the edges, to make them softer, then I bent them by hand. But they did not fit perfectly.

I've been dreaming of making skis for a long time. That dream is now reality. A partner and I will be constructing a few pairs of skis as a final research project to our education.

The first pair of skis will be dimensioned at 125-96-116. We will be using a vertically laminated birch core, with durasurf topsheets and bases (Thanks, Dave)

Here are the following materials we will be using and the price of each in CAD

- 1 Gallon West Systems 105-B Resin. $110

- 1 QT West Systems 206-B Hardener. $44

- 6m Durasurf .048", 6m Durasurf .025" HyperClear $TBD

- Edges: We are having to harvest edges from old skis and from botched layups form a local ski company. Cost is our time

- 14'x50" (58 sqft) Vectorply EBXM 1708 $20 (half price. He liked our project)

- 2 Sheets 3/4" MDF for the mold $Free

- Kiln Dried clear Birch $Free (friend works at a mill)

Today we cut our mold from the MDF. Here is a picture:

Tomorrow we'll be laminating our cores and coming up with our desired profile. Once the adhesive has cured we will plane to a maximum thickness, attach the sidewalls and use the CNC to profile the cores.

By the time we have done this, we should have our base and topsheet material. We will use the CNC to cut this as well. We will be using a vacuum press to press our skis.

We were unable to get any triaxial glass unless we wanted to order a whole roll. This was way out of our price range. We ended up purchasing some marine biaxial glass with random matting on one side. It weighs in at 31.42 Oz. these will be heavy, damp skis.

We plan on sacrificing one pair in the name of testing. We're working in a pneumatic longitudinal flexing system with strain gauges embedded at different locations within the ski. We are also trying to come up with a way to test the ski's torsional rigidity as well as vibration properties. We plan on programming a PLC to run the test system automatically for a long period of time and record the results. We'll be looking for any fatiguing, breakage or significant change in the flex and internal stresses of the ski.

Time permitting we'll also draw up 3D solids models of the skis and use COSMOS, an engineering design validation software to virtually analyze and stress test our designs. This has no real purpose but to look good in a fancy report.

We will probably rig a strain gauge to some part of the ski in the press and monitor the pressure it produces, and how consistent it is. We'll find a way to graph it in realtime.

This project started out as a personal interest project, but with the addition of some automation and electronics I turned it into a school project.

I'll take more pictures throughout the process and post them here. We plan on having a few pairs done by April 17. We'll then go on a road trip to test them in the gnarliest spring conditions we can find. Pictures of that will also be posted.

I'll also eventually get around to posting the CAD files for our core, base, and mold.

Wish us luck

Rock on! It looks like you have some great toys to play with building your skis. Best of luck, and I really look forward to seeing what your results are.

I apologise for the poor quality of the pictures. My phone is the best we've got right now. We are still waiting for our topsheet and base material, so in the meantime we are working on an automated testing system for our skis.

We're going to compare the difference in flex in relation to core stiffness using birch and biax glass.

This is the equipment we will be using to test the strength/flex of our skis.

2 small pneumatic actuators to clamp the ski in place at each end.

1 large pneumatic actuator to apply the force.

2 Electronically controlled DCV valves

1 pressure regulator

2 Photo proximity sensors. These will measure the deflection of the ski

1 Pressure transducer. This will tell us the amount of force being applied to the ski.

1 Allen Bradley PLC This will allow us to automate the testing process and trend the results to a graph for later analysis. This will come in helpful when we have to leave the shop for the night.

1 Start/Stop button. Buttons are fun.

Will will construct a heavy duty frame out of MDF for this. We've got the pieces cut out. All we;ve got to do now is assemble it and take care of all the wiring and plumbing.

Here are our birch cores being laminated together. We used epoxy.

Here is our mold. As mentioned it'll be used in a vacuum press. Since this photo was taken we've cut out more MDF ribs and filled in all the gaps.

Due to an edge material shortage we were forced to salvage the edges from old skis. This was not easy. I only hope our skis are as tough to destruct as these old Salomons.

If all goes well, our base, topsheet and edge material will arrive sometime this week. We will lay up a few pairs of skis and test them out before the hills close in the beginning of May

Nicely documented.

I hope you can keep documenting your work like this.

Is your mold a fixed size mold? From your description I would say it is.

Regards,

Geoff

Yes, our mold is a fixed size mold. Due to time constraints we didn't put much thought or time into our mold. We hope to construct another that is adjustable.

I received the base and topsheet material last night, and if all goes well we will lay up our first pair sometime this evening.

I finally made it!!!!!!!

Two weeks???

The epoxy L+L needs at least 12 hours under pressure plus 8 hours.

In 24 hours they are done.

Go skiing!!!

The 100 years old balance is too cool!!!!!

I know, but I'm back in karlsruhe and the press is in ulm. I had to go to university...

On Sunday I have tested my new ski. I only finished one ski, so I combined it with a 1080. (171cm)

It really worked well!!!

I want to thank you for your tutorials, advice, pictures and materials! Especially to davide. without your edges and base I would have never build the ski.

check out the new pictures and videos at http://www.stud.uni-karlsruhe.de/~uryo/karsten/

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Super!!!

That means that bith vacuum pumps and pnematic presses are not necessary to build skis. The wood/clamp press can be a real, cheap alternative.

yeah, it was really cheap!

i payed 25 euros for it, but i already had some materials, for example the plastic plate. but you could also use a wood plate.

So, at the end, you made the skis with a single ash board, rather than using vertical lamination, is it right? Did you pre-bent the board with hot water? How thick was the core?

yes, i used a single ash board.

2mm thick at the tips, 11mm in the middle.

i didn't bend it before, i just put it in the press and it was alright.