Ski Builders Forum

Thks OAC - I will get it dialed soon. The edge bender is the key item. Picked up a bit more aluminium today from a local foundry ... never knew it existed.

If you get the itch to give it a try, feel free to shout. I suspect it is possible just to do the tips and with your vacuum press, you're ideally placed to cap those suckers too!

Takes a bit of time to get to this stage ... reduced the expansion gap to 0.45 mm.

Topsheet on the way, upgrades!

Very very professional and nice looking work their Rich!

Cheers Tom - I need to crack on.

Have solved how to locate the cassette top. Now I just need to re-build my press, cat-track, add another hose and bottom mould, then I'll be able to use it

Going forward, I'll test the topsheet against varnish and see where I end up - might have to PU the topsheet, as my fibreglass is quite course ...

Impressed by the way the ski rides out - its a solid base from which to modify and upgrade.

Great cassette!

Now I have a ski that I am happy with (as a good template for future development), I look a bit of time out to fix my planner crib - no glue. I key element is the accuracy of the sides - I had templates already, so they were made quickly. I think this could be adapted to allow for a variety of shapes, but I'm short on time. Sorry, the photo's aren't so great, but good enough?





The tape pressures the sides and will be quick and cheap to replace when it fails in the future. It currently binds the core to the shape of the crib - strictly speaking, I don't think it is necessary because the rollers within the planner will do this.





The 'stop' at the end is really basic, it will change shape soon, my poor little mind can only cope with so much change at one time : )

Templates - the ones used to attached sidewalls



SD - thks for your comment. Once I have the press together, I am going to face the challenge of making all these things fit together ...

A lot of this information is within the forum or generally hinted at, so I don't think I'm too wide of the mark- fingers crossed. MM - this is what I will be doing. I'm not saying this is all entirely necessary, but I believe these steps have their advantages.

Ensure epoxy is stored at a temp to avoid water in the epoxy - decrease the potential for void growth during the cure. Not a big risk given the small volumes purchased, but reduces the chance of bubbles. Currently stored at 15 - 20 oC using a 60W tubular heater and a time controlled socket, external temp 0 oC. Old cardboard box wrapped in insulation.

Pre-define the final pressure upon the basis 60/40 ratio fibre/epoxy, I think it is around 45 - 50 psi for my fibre, running tests a few tests.

Define the temperature for wetting out, Suspect from experience it will be around 35 degrees. Wet fibre and remove from heat to avoid reduced lay up time - I'm a bit slow. Fibre has been in airing cupboard over night prior to lay up to remove any moisture - the roll is currently stored in the garage : ( Mold will be pre-heated to same temp.

Define the rate for ramp - I think 10oC per min is OK from what I have read, but not sure if I can achieve this, as my heater are a little fragile. Pressure to 40 psi and bring up to around 60 oC, allowing excess epoxy to bleed. Not sure about how long to hold at this temp - not long I think, maybe a minute or two - will know more when the epoxy/fibre ratio has been worked out. Ramp to final temp and pressure - keep an eye on pressure and allow to soak until the required Tg value is reached.

It has been a matter of heating the fibre etc to ensure everything wets out well and then pressure. This appears to result in very good wetting out but above average amounts of epoxy, approximately 100g per ski including waste, so will see how this changes the result.

Search 'Google Books', 'epoxy kenetics' and 'epoxy ramp'. 'compression molding' etc has been helpful. Eg:

http://books.google.co.uk/books?id=ke7T ... le&f=false

http://books.google.co.uk/books?id=aCm9 ... re&f=false, pg 408 for compression moulding.

Again very tidy work, last picture not showing?

Worked through extending the press ... I-beams became HH, which means everything is bolted together.









The table top works well, wet out and then drop the materials into the cassette or put them to one side while and let the layer amalgamate







Wetting Out - 40oC is giving great results when wetting out, very little extra work required. It just pin points what I have been doing. 35oC is OK to, depends on surrounding temp at the moment.



The cassette works well with the core. All done by hand. Have been finally found someone with a slip roller for a reasonable fee. The core is a little tight at room temp, needs a bit of a heavy tap to get it in. The cassette expands by 0.2mm at 80oC, which means I will probably pull it out at 60oC and take the skis out then instead of waiting until it is cool - I think that this is the right thing to do?. Will find out over the next couple of days. The reality is a cassette is a lot of work, which I have done while ironing out other issues. Going forward it should be a matter of design and not process.

BTW, if anyone is looking at any of this and seeing their work or ideas. Sorry and thanks at the same time - you end up reading and seeing so much when researching, it all becomes a bit of a mush : )

Nice work Rich! I noticed your cat track has a layer of fiber board (or thin osb, mdf...) attached to it. I haven't noticed that in other cat tracks, but I like the idea. I just had an idea for a new style cat track I'll post it in a separate forum/post... Thanks for planting the idea.

How long before we skis?

It's hardboard - the method inspired by Folsom (again). I'm not sure how robust it will be long term, but it's a cheap solution to holding back the excess heat. The screws at the very ends should be drilled when under pressure, otherwise they will show signs of wanting to rip out. Looking forward to seeing your revision.

I've a few points to refine with the press ... mdf base doesn't like the heat and pressure. I will switch to ply and make it wide enough so it can slide out and create a shelf upon which I can rest the cassette. A piece of baton at the rear running parallel to press length will cantilever against the cat-track and creates a bit of clearance for loading

Hope to press this week!

This tray was helpful with loading



But I've not created enough space and things became a bit tricky, so I went with just one heater as I was getting pushed for time. Turning the heater up a little became the next best idea .... an extra 20 volts.



hmmm... crispy!

So, mid process - deflate, remove and replace ... oh yes, that's gonna turn out well



Errr



Oh



But at least I've learn how to make a flat ski ... would trade this experience in



So this could have been much worse! I hang around and watch the press. They came out of the mold and the edges look good; in terms of how they meet the base. I will remove the flash and see whether everything located correctly.

I should layup within a mold, but possible not this mold. Don't know right now, as this is a lot of work heading for the bin

Heading for the bin? They look pretty decent in the pics. The edges look real good, that's a tough battle right there. Post pics after you've cleaned them up. I like the veneer top sheet.

well, now we both have one burnt heat blanket

The cure was badly interrupted and has suffered as a result. I have cut one out of the flash and it cracks when flexed.

The edges have worked well, but going forward I need to change the tip shape. I'll take a few close ups SD, but like Twizz said, its easier when they reflect what the curve the edge bender creates ... I just need to iron out these last few kinks. The mold needs vents for the epoxy to flow away from the base for one.

The topsheet is borrowed. I'd like to give them a semi-natural finish. Ideally, rub in the mix of ski wax and white spirit used for the sidewall, as snow doesn't stick to the surface.

Chris - It's not a great club to be in, but at least the company is good.

Regardless of the heat blanket, that cassette is a work of art. You should be really proud of that, certainly the best cassette any home builder has done thus far.