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lets make skis

Posted: Thu Dec 21, 2006 1:25 pm
by burny
So, as my project is finally working out, I thought, I'll post my progress here. But to begin, here are two different völkl skis I cut in half to take a quick look inside.
This ski is a usual Völkl P40. The woodstrips are 5mm wide.

The second ski is a racelab Slalom Völkl. You might notice the much weaker titanium sheet. I still wonder about that because this ski actually is stiff as hell an quite heavy as well. Maybe there is just a loooot of carbon in it.

Posted: Thu Dec 21, 2006 1:43 pm
by burny
Ok, but now for my own skis ...

first of all I'll introduce the press. To be honest, I'm really glad I can use all this equipment because it makes everything super smooth and easy. I'm working in the carpenter and joiner factory of my father in law. I usually help him out when there is a lot of work to do and then, after having worked for 10 hours, I do some whatever I want to build thinking and building. At the moment that are skis. The bad thing is, I dont have a lot of time and usually fall deadlike into bed even without helping him out.

Ok, heres the press. In fact its a veneer press, but theres more than enough pressure coming out of it and its heatable as well.

here you can see what this baby can do

I use obachi wood (german: Abachi) because its super light (lighter as poplar, heavier than balsa, I dont have the exact figure at hand at the moment), has long fibers, is realatively resistant against physical abuse, AND its fairly cheap. I still have some planks.
I cut the planks in strips of 7 millimeters and then planed them with a planing machine down to 5 millimeters on each side by 1 mm. Worked out really fine.

heres an image of the strips

and here a detailed view of the wood ... already planed.

this is the planing machine, the one in the middle that looks like a big box. the planing knifes are at the bottom, on top I have several rubber rolls and I can actually go down to 1,8mm thick strips. you put the workpiece into it like a letter into a postbox, kind of ... it gets sucked through automatically.

Posted: Thu Dec 21, 2006 1:57 pm
by burny
so, today I glued the strips together ...



the next steps will now be planing the up and downside of the woodcores, next I'll cut out a negative core profile out of some larger plank with this nice little helpful thing:
edit: the picture of the cnc machine messed up the thread ...

I'll place the woodcore into the negative and let it run through the planer -> profiled.

Next I'll cut out the actuall form of the core with the cnc machine again. Btw. the cnc/dxf files are already written, that work is done, and it was a lot of programming ...

But until now, thats it ... I'll continue after chrismas when I have some days off. God bless Ullr for not sending snow to yurp until now, else my skis would be finished in august.

and here a picture of some chairs you will certainly not find at Ikea. Note the back of it is bend into 2 directions, according to my father in law it was incredible hard to manage that, it took almost two weeks. Its a special customer who found chairs like these in an antique shop but only very few and needed the same ones again.

to be continued, hopefully soon ...

Posted: Thu Dec 21, 2006 2:30 pm
by burny
maybe this is also interesting to the sb community, I've cut of the stupid tail of my gotamas. (@alex: you can be relieved, although they now, beeing in andermatt without any snow except a meter of light pow, suffer from several coreshots I didn't retire them ... for now, hehe).

here are the pics. I've noticed, they consist of nothing more than 2 fiberglass sheets under and two sheets over the core. The sheets are quite crude, nothing like fine 240g "atlas" or else. Must be the least expensive stuff in china I guess they used. One sheet is bidirectional from tip to tail and from side to side, the other one is bidirection in a 45° angel, but I'm not 100% sure because epoxi bonds relly well and I really had to rip everything out by brute force. Next thing, there are just 11 carbon rowings, from tip to tail (it seems, because the rowings are woven into one of the fiberglass sheets.)

I just thought you might be interested.


and the cut gotama, its interesting to see, how far back the bindings really are ... thats the usual freeride mounting point


Posted: Thu Dec 21, 2006 11:51 pm
by littleKam
2 sets of pontoons?! Never really noticed how early the tips and tails start their curvature. Thanks for sharing the pics. Definitely very jealous of your access to that sort of equipment.

Interesting pics of the Gotama tails. Is that black stuff in the center a rubber/plastic layer (between the layers of glass) or did your saw burn the core?

Posted: Fri Dec 22, 2006 12:38 am
by burny
the black stuff is some kind of spacer ... the woodcore must have ended earlier.
only one pair of the pontoons are mine, I got a fairly good deal on them and the second pair is for a friend of mine.

I know, I'm very lucky to be able to use all that equipment ... I guess I'm less a hardcore skibuilder by using it all. :D

Posted: Fri Dec 22, 2006 1:56 am
by plywood
littleKam wrote:Definitely very jealous of your access to that sort of equipment.

so where do you live? in winterwonderland?! damn, what would i give to use such an equippment AND having 2pairs of pontoons! :D

sometimes life is just not fair ;)

so, if your skis just come out just half as good as your equippment is, you`ll become a pretty acceptable result.
i`m looking forward to read your progress!

Posted: Tue Feb 19, 2008 9:57 am
by burny
so, here they are ... actually they made it off the press much earlier (already in december) but if there is one thing I dont have its time.

I'm actually quite happy about the result, however the skis do have some minor faults. The topsheet shifted a little and gives you a little insight. Not that beautiful but well, I'm happy. The lessons are learned and the next pair will be better.

The testdrives are done, too. Went to Chamonix to take favor of the perfect steep skiing conditions. By accident I run into Idris in the skibus. He has really nice skis, too bad we only had about 5 minutes to talk. Cheers Idris, was nice to meet you!

Hopefully there will be a skibuilders meeting in Europe, soon. As far as I know plywood is trying to organise something, my suggestion would be Andermatt, thats a place everybody can reach within an acceptable distance.

ok, now let some pictures speak.

pressing the forms. I cut them out by cnc and put them together using dowels. after the pressing everything was sanded on a band grinder, very exactly, very even.

cnc cutting the base. its done by taping the baselayer on some planks.

these are the cores, the trick to get the form, thick in the middle, thin at the ends, is by putting them through some kind of grinding machine that grinds down planks by 1/10mm. So I put the raw cores on a plank that got the correct convexity in some negative form and let the core, together with that negative patternplank through the grinder. Some rubber rotors press the core into the negative and the knives cut out the correct form of the core. kiss - keep it simple stupid.

next: building it all together ... I dont have the exact build up in mind at the moment but i wrote it up and will post it later. its: glass, uni and biaxial, some carbon strings, some glass stings, more glass, somewhere the core varnish and yacht paint.

and at last, the finished product. unmounted


in action (well yea, its always me taking the pictures, so there is only this rather boring one with a pretty lame move, sorry)

rappelling, at last this one shows a little bit of excitement

over all I'm satisfied with the result. they hold the edge very well in very steep and hard conditions, it was possible to ski down an icy 50° slope (alternative to the Rectiligne Couloir, the orange one in Baud's book :D ) and did everything well all week long. Also we had to manage some pretty rocky and tough conditions I didnt get any coreshots and the edge kept in place, although I ripped them out a little at some minor places. As soon as there is a little powder the ski starts floating instantly, the superlong and soft tip pays off, the bad side of this is some shattering on very hard snow and gonig at high speeds but still manageable. As I usually intend to ski pow I can live with that but the next skis will have a stiffer tip, will float as well and wont shatter as much. The torsional stiffness is just incredible and my plan to build something as stiff as this one worked out really fine, its done by 5mm woodstrips for the core and several layers of biaxial glasslayers going 45° towards the edge.
The skis are very light. 1600 grams each ... Size: 186 124-105-110 (about, I dont have the superexact figures in mind at the moment). The abachi cores hold the bindings very well, my concerns are resolved. But maybe that pays off because of all the glass and carbon layers, at last, it works. I'm happy.

Posted: Tue Feb 19, 2008 11:38 am
by plywood
nice to see some more pics over here ;)

could you make a picture of the camber/rocker? did i get it right that you have zero camber/very little camber underfoot and a big rockered tip with flat tails?

about the meeting: there is something going on ;) i`ll let you know as soon as we know more, up to now it looks like i`m organizing something together with dan graf (maybe you know him, he set up a page about building snowboards years ago, same stuff as we do, but wider boards ;) )

Posted: Tue Feb 19, 2008 12:43 pm
by burny
hmmm ... the rappelling photo shows it quite well.
here are pics of the form, maybe you can get a better image that way.



Posted: Tue Feb 19, 2008 1:51 pm
by Skierguy
First off burny, great looking skis. What veneer did you use for your top sheet? Are you happy with the durability of the finish? I am intrigued by you photo’s of sections through the two Volkl skis, specifically the area above the edges. The core appears to be routed significantly higher than the edge tabs resulting in a comparatively large amount of epoxy between the core and the edges. I noticed this as I am currently trying to determine the best depth to rout a relief in the cores for the edges. What depth did you rout under cores to allow for the edge tabs? Do you think that had anything to do with the edges coming loose in areas?

Posted: Wed Feb 20, 2008 12:10 am
by burny
i used markassa veneer ... I dont know if its the same in english, thats the german name.
I didnt rout out anything for the edges and it worked out fine. I guess the edges get pressed into the core, the obeche wood is rather soft and I didnt use any specific sidewalls, its just the core. it works, i wouldnt rout out anything above the edges. the woodcore might shift and then those carved marks wont to any good.
The edges coming loose (well, they still are bomber compared to other skis) results of stone contact, not the construction.

Posted: Fri Mar 28, 2008 1:48 am
by pau
hi congratulations for this nice looking skis!!

you used a veneer press, did you have any problems with it? are there any special things to be aware?

what i know:
-the mold has to be verry exact (yours look really graet)
- you have to put some "soft" layer between the molds to distribute the force constantly over the ski

Posted: Fri Mar 28, 2008 3:08 am
by burny
I had no problems using the veneer press ... as you mentioned i've put a soft layer between the press and the mold, I took a 1.5cm sheet of rubber. And my mold is very exact due to the cnc cut.
One thing that can happen is the veneer to not stick to the rest of the ski, this can happen any time pressing veneer onto whatever, not ski making specific. looks a little like bubbles and doesnt happen often. if you use more epoxy then minimum required it has no effects, otherwise you might get those bubbles and they, of course, happen to open up and fall away during skiing and it doesnt look as clean anymore ... doesnt do anything negative to the ski however.