my story of ski building

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

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novaskis
Posts: 27
Joined: Fri Mar 25, 2011 12:29 pm
Location: nova Scotia, Canada

my story of ski building

Post by novaskis »

i have been lurking on this form for almost two years, and all the while slowly constructing skis of my own. i finally turned out my first pair of skis and got to used them about two weeks ago, so i figured since everyone here has been such a great help i would post my story.

i started out thinking i would make a vacuum press and go from there. my mold was super basic and i was trying to make it as cheap as possible.

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the mold has 25mm of camber (alot i know) and 300mm radius tips, but i will come back to that. i how ever stalled out after competing this mold, i didnt like the possible product i would have verses that which i would get with a pneumatic press. how ever in my final semester of school (civil Engineering) a prof took us to a structural steel fabrication shop for a tour. after the tour i met our tour guide and spun him my tale of ski building. he gave me his card and told me to email him what i would need and we will see what we could do. a month later i have 4 8 foot lengths of 10" I-beam sitting in my parents driveway at no personal cost.

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after finishing my exams in december, i went to work building a press worthy of the likes of headmonkey. i spent a few weeks measuring drilling, drilling some more and then drilling a bit more to finally construct this :)

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it came in at a little more than 1600lb (725kg) of steel that according to my over estimated calculations would deflect less that 1mm at 100psi. not bad for paying almost nothing for the beams.

things picked up from there, modifying my previous mould to work with the increase load and making the cat-track bladder and top mold.

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while i was going all of this i produced my base template, profiled cores using a reverse router bridge kind of method, bent edges, cut base and generally setup to produce a pair of skis. i made a few other odds and ends that are on my flicker account if you would like to look, including an air system that i am pretty proud of.

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two weeks ago i put it all together and pressed a pair of skis, i had to use a big propane heater to heat up the garage so it would be warm enough for the epoxy to kick but i did it.

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and the final product turned out great :D . after 14 hating the garage and another 12 or so in the press i pulled this out

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spent a bit of time cleaning them up to finish with this

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they were far better than i could have hoped for. solid maple core, out door varnished sidewalls and fiber-glass tip spacers. 140-105-140 dimensions and 2.5-10.5-2.5 cores.

i mounted them up and took them skiing. to my total surprise and delight they worked phenomenally, stiff and responsive. carving hard at high speed and flexing about as perfectly as i could have dreamed. and all on hard icy snow.

they now have 3 days on them with minimal degradation (minus the slight de lamination due to a failed hand drag 360) and i have more people at my ski hill asking for a pair than i can count.

i want to thank everyone here doing what they love and talking about it to inspire me to follow in their foot steps. and especially plydude for all his tips and encouragement.

i am also not sure if my image posting worked but if i messed that up i apologize. i am kinda new to this form stuff


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novaskis
Posts: 27
Joined: Fri Mar 25, 2011 12:29 pm
Location: nova Scotia, Canada

Post by novaskis »

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i hope this one works
skidesmond
Posts: 2337
Joined: Tue Apr 07, 2009 3:26 pm
Location: Western Mass, USA
Contact:

Post by skidesmond »

That's a helluva press! You s/b able to press much higher than 40psi. Super job on your first pair. All that lurking really paid off. :)
novaskis
Posts: 27
Joined: Fri Mar 25, 2011 12:29 pm
Location: nova Scotia, Canada

Post by novaskis »

i feel really dumb for messing up all those pictures but i think i have got it.
so i will repost the pictures only in the order they came up in my first post

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again sorry for the screw up earlier
novaskis
Posts: 27
Joined: Fri Mar 25, 2011 12:29 pm
Location: nova Scotia, Canada

Post by novaskis »

yes skidesmond i my press would most definitely take alot more than 40psi.
my bottom mould however was build for vacuum bagging so it would not take much more than that. i had to make some modifications to get it to take the 45psi i pressed my first skis at.

and thank you i am pretty proud of the finished product.
novaskis
Posts: 27
Joined: Fri Mar 25, 2011 12:29 pm
Location: nova Scotia, Canada

Post by novaskis »

so i have left my thread alone for a while but i have been quite busy on the building front.

between work, girlfriend and life i have made three new pairs of skis, gotten a planer and jig for profiling and streamlined my finishing process.
i have to say i am rather impressed with my progress.

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from right to left
first pair made with maple core, second pair made with solid poplar core, third pair made with solid oak core.

i ended up getting a whole roll of base material as waiting for 2m sections was just too much for me so i descided to try something different on this last pair. i took a piece of base material and used it as a top sheet. i taped it as i would a base and pressed the ski with it included.

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the result was way better than i could have expected :D

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for this last pair i built myself a router table and 15º bevel guide to do the sire walls. if it werent the first pair of skis i had done they would look professional.
twizzstyle
Posts: 2204
Joined: Tue Mar 07, 2006 8:25 pm
Location: Kenmore, Wa USA

Post by twizzstyle »

Those look great!

Interesting that you can see the tip spacers slightly through the top sheet, is the ptex slightly translucent, or is that just shadows?
novaskis
Posts: 27
Joined: Fri Mar 25, 2011 12:29 pm
Location: nova Scotia, Canada

Post by novaskis »

acutally for tip spacers i have used mat fiberglass built up to match the core thickness. the glass ends up translucent so you can kind of see through it.
the tips end up really tough though and delamination is really a non issue since it is one solid piece.
rockaukum
Posts: 558
Joined: Fri Nov 03, 2006 9:23 am
Location: Placerville area

Post by rockaukum »

Just visited your post, skis look great. Wonderful feeling when it all works!
One thing I see in your pictures that causes some concern for me. It has to do with your press. There is a rather complete posting on the use of Ibeams and how to utilize their full potential. The basics of it are that the Ibeam supports need to be around the Ibeams not attached via the center flanges. I picked up a press like yours, being used with success until it started to pull the beam apart (flange from center I portion). I rebuilt the press with the supports going around the outside of the ibeams. Anyway this is what I got out of the article.
Look for Kam's recent posting on his Kubali press and You will see what I am trying to say...
ra
novaskis
Posts: 27
Joined: Fri Mar 25, 2011 12:29 pm
Location: nova Scotia, Canada

Post by novaskis »

what size are the beams used in your press to start with ?

i ask because i am an engineer and when i designing this press i was taking both steel design and finite element analysis. for practice i did every possible failure mode and model i could think of on it and if i did my calculations right the bolts will fail before i get the rotational failure you are describing.
thats not to say i am infallible but i do appreciate the concern.

i am interested in the thread you spoke of though. i thought i had read just about every thread on this form (or at very least skimmed them while pretending to study:) )
skidesmond
Posts: 2337
Joined: Tue Apr 07, 2009 3:26 pm
Location: Western Mass, USA
Contact:

Post by skidesmond »

I'd be interested to know how the skis w/ the p-tex top sheet ski relative to being damp or not. Let us know.
rockaukum
Posts: 558
Joined: Fri Nov 03, 2006 9:23 am
Location: Placerville area

Post by rockaukum »

Here is the press (metal) that I was speaking of.
viewtopic.php?t=1349
I tried to find the postings on why you should build the bracing around rather than on the inside (as shown above) but have been unable to do so. I'm no engineer but do remember rereading that posting several times to ensure I did it "correctly".
Maybe someone else can chime in if they remember the posting....
My press...
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novaskis
Posts: 27
Joined: Fri Mar 25, 2011 12:29 pm
Location: nova Scotia, Canada

Post by novaskis »

interesting. i understand the theory behind what you are saying though. your set up works more like a simple beam where as mine does have other actions that could be problematic. that being said your beams look like they were sections of plate steel welded to for i beams. not a bad way to do it but if the welds dont run the whole length of the beam you will no doubt get failures like the one that happend. i could be wrong but thats what it looks like to me. my sections are rolled sections so they are one solid piece. the pull away action you saw is alot less likely with out destroying the web section as well.

again though this is in theory i could be wrong

skidesmond

i had not thought about that aspect it might make a difference
how ever i am not sure i have a good control to check against. while almost every aspect about the skis is the same as my initial pair there is one other major difference besides the ptext top sheet. now i know this is frowned upon because epoxy is a superior product but i had a ton of polyester resin left over from some repair wrk my dad did to his boat (a 10gallon pail was cheaper than 1 gallon of the west systems that is available locally by alot).
so far the bond has been alright. i did a test bond before laying up the skis and it is rock solid now.

with any luck they will turn out ok but as always with experiments its best to keep your fingers crossed anyway
rockaukum
Posts: 558
Joined: Fri Nov 03, 2006 9:23 am
Location: Placerville area

Post by rockaukum »

Correct, These are welded I (like you) think that this was the main culprit as to why their press failed. I continued the weld to the end after pressing the flange back into place. I just wanted to avoid any future possibilities.
ra
twizzstyle
Posts: 2204
Joined: Tue Mar 07, 2006 8:25 pm
Location: Kenmore, Wa USA

Post by twizzstyle »

There are lots of people with presses built like Novaskis's. See Happy Monkey's site...

http://www.happymonkeysnowboards.com/Mo ... nstruction

Should be no issue, especially since it sounds like you did some proper analysis before building it.
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