Ski Builders Forum

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.