Shopvac's Skis

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shopvac
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Shopvac's Skis

Post by shopvac »

After 8 months of building we finally have a pair of skis to show off. Thanks to everyone for all of the information. Great website.

Some specs and info:
191.5cm long
134mm underfoot
Bamboo cores (3mm, 13mm, 3mm) with bamboo sidewalls
Pau Ferro wood veneer topsheets with Minwax Helmsman spar urethane
22 oz triax fiberglass above and below from Raka (used Raka epoxy too)

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I fixed the picture... sorry about that.

My brother and I will post a full report soon. We used a cloth press frame like Plywood (thanks Plywood!) so we will show that to everyone as a nice lightweight alternative.
Last edited by shopvac on Mon Oct 13, 2008 4:00 pm, edited 3 times in total.
Nick's Sticks
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Post by Nick's Sticks »

Good job, those are nice looking boards. I like the matched pau ferro veneer. Great color. When do we get a TR?
"Powder days? Everyone loves powder days. You can ski powder days the rest of your life. I prefer ice, its faster." -Glen Plake
ben_mtl
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Post by ben_mtl »

very nice job !!

For the pics from picasa, the easier is to open the image in picasa, right click on it to get the link and that's what you paste between the "IMG" tags when posting. Hope it helps.
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shopvac
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Post by shopvac »

Thanks for the comments guys (and for the help ben_mtl)

We'll try to get a full TR written up soon. Between school, work and getting ready for ski season we're both pretty busy...

The skis were just sent off to Alpine Base and Edge in Boulder to get a base grind and edge. If Loveland decides to open this weekend they might just have to take their maiden voyage.
plywood
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Post by plywood »

dude, those skis look amazing! i really really like it. and i`m looking forward to your report ;)
plywood freeride industries - go ply, ride wood!
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shopvac
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Post by shopvac »

My brother and I started in late February getting the fire hose air bladders sealed. Thanks to some great information on Headmonkey’s website we knew exactly what to buy from McMaster-Carr and we were able to build a fire hose air bladder that does not leak.

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There are two things we would try if we were to build another set of air bladders in the future.
1. Buy wider angle iron. Maybe use angle iron that is 1.5”x1.5”. We used 1”x1” and it works … but let’s just say it was less fun than 1.5” angle iron would have been.
2. Try and buy angle iron that already has some holes drilled in the material. I think at McMaster this was an option and it would have saved a lot of time hovering over the drill (my brother wanted to get this and I said no, now I wish we would have).

Next, we sketched the tip and tail mold pieces up by hand. We are using a small tail that rises around 25-30mm in 150mm of length. Our tip mold has some tip rocker. After looking at my original drawing it looks like it has 20cm of rocker length rising 13mm before the regular tip starts. The regular tip has a radius of 15cm. We were hoping to create a tip that was going to be roughly 60mm off the snow.

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We made copies and cut them out. After gluing them to some ¾” MDF we cut them out to the best of our ability with a shaky hand and a jig saw. They came out pretty good and after a little light sanding them were deemed fit to copy with a router and a pattern bit.

First we rough cut the approximate shape with a jig saw.
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Then we attached the rough cut piece with double sided sticky tape to the template in a small nest we built that had some rails for the router base to rest on. This made life so much easier when cutting out the small pieces.

Here is the nest we built for the tip mold.
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My brother routing out a tail piece.
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The finished tail mold and tip mold.
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Tajma approves.
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The rest of the bottom mold is made up of 3 inch thick MDF that is flat. For our first pair of skis we wanted to do a flat or zero camber mold with some tip rocker and just see what we came away with. This was also the easiest mold to build. The top mold is MDF as well and can be adjusted in 8cm increments. I screwed up the length of the top mold template so now the shortest skis or boards we can build are 183cm. Oops. Measure once … cut twice … can’t fool me again … or something like that.

The press is starting to come together (missing the ¾ inch MDF middle section that can adjust the bottom mold length very easily while making the tip and tail molds intersections with the flat camber mold less sharp). The press cavity is 17 inches wide and can make skis 215cm long if we really wanted to.

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Now we needed a cattrack. We did some searching on skibuilders to see what people we using and after scratching our heads and emailing Plywood a couple times we went with a wooden cattrack. It was very easy to build and cost us nothing because we got the wood for free. We used a really nice router table with a round-over bit to clean up all four edges of the 1in by ¾ inch pieces. Then we decided to hold it all together with some climbing webbing we had from our old slack line. We ended up using the biggest staples we could find to make sure the webbing would stay. We spaced out the wood pieces near the tips and tails so that it would be able to conform to the tight radius in these areas. I think this worked out pretty swell.

Action skibuilding photography.
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Putting the pieces together.
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Now comes the fun part. We have looked high and low for some cheap I beams without any real luck. After scouring the forums for alternate press frame ideas we decided to go with the cloth bag style press “frame” like Plywood has used. He has been building some very nice skis so we figured we should give it a try. We went to the local fabric store and bought $30 worth of duck cloth. I think we needed 4-5 yards at 50 inches wide. Neither my brother nor I know how to sew or have access to a sewing machine so we took the fabric to a seamstress here in town who was very eager to help us out. He made us two bags or tubes of the same size for just under $50. For Around $80 total we had our press frame. We brought it home in a backpack on our bikes (not many press frames that can be transported in a backpack). The duck cloth is sort of like the material they make Carhartt jackets and pants with. It was the best cloth we could find but I think other fabrics would have worked as well. We have filled our press to just over 40psi without any problems.

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We have since built a rolling cart for the press molds to sit on which makes life so much easier. The entire press lives in the corner of the garage now totally out of the way. We just wheel it out when we are building skis so can work/lay-up skis from both sides of the press.

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I think we had the cloth tubes sewn a little too large because we have to add a lot of 2x6’s above the top mold. Overall, we are very happy with the press. We do have a couple problems but we are sorting those out. The tips didn’t get pressed all that well on our first build and I am thinking that we needed to add even more wood above the top mold so the distance between the top and bottom mold is decreased. I think there have been some posts about this already but any insight would be helpful.

That’s all for now as it is approaching midnight … I will continue with more photos and the build log from our first pair of skis.
Eight
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Post by Eight »

Wow. I'd not seen that cloth method before - that's amazing.

I'm tempted to try that.

Edit: the more I look at it, the more I can't believe it stands up to 40psi. Great work guys.
kfarrar
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Post by kfarrar »

Can you tell us more about the method of creating the cloth bags?

I have a sewing machine kind of remember how to sew.

How did you find out about this method?

I have some webbing from restoring furniture. I'ts quite strong and I wonder in the same could be accomplished by creating like 8 bands to wrap around the press.

Why aren't more people using this method if it (1) Is cheap(2)Does the job?
Norwegianskier
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Post by Norwegianskier »

I too hot really interested in using cloth instead of building en expensive steelframe.

Can anyeone come up with som pros and cons?
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shopvac
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Post by shopvac »

Thanks for the comments.

Eight -- it is amazing it works. We were very pleased with the outcome.

Kfarrar: We found out about this method from a post by Plywood. http://www.skibuilders.com/phpBB2/viewt ... c&start=15

He has since built another cloth bag ski press frame and it looks like he has been busy making some nice skis on these two presses. We emailed him a couple times to find out about which material we should use and just gave it a try.

Plywood was not sure what type of cloth he used. My brother and I just went to the local fabric store and found the thickest material we could find. It seems to work. I would guess most stores will have something similar that will work. Again, we are using "duck cloth" that looks and feels like the material they make Carhartt jackets and pants out of.

I would not use thin bands because that wouldn't distribute the pressure over as large of an area as we are doing. If you think about it, our cloth bags have to hold a lot less per sq inch than a small thin piece of webbing would. I don't have any calculations for this system but I did do all the calculations for an I beam press so I have some ideas on what these cloth bags are holding.

Norwegianskier -- Great idea. I will list a few we have found.

Pros - Cheap, light, easy to construct (no welding or drilling through thick I beams), can still use a cattrack, can add heat later easily.

Cons -- Can't see inside the press to make sure everything looks good, it is a little tricky to pull the bags over the molds because we made the molds out of heavy MDF, with a two wide ski press it can't really be done alone, I-beam ski presses have everything like the bladders and top mold already aligned and where they need to be which would be nice.

Overall, I think the bags are a decent way to go. I would make the molds out of a little bit lighter material if we did it again and maybe would just make a single ski press with heat.
plywood
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Post by plywood »

awesome, so glad that it worked out for you too!

my biggest concern was that the mold could snap in two pieces lenghtwise if you build 2 skis at a time. but i think your 2x6 really helped prevent this.

i made a little illustration ;)
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version A is a regular, flat mold for two skis. yellow things = firehoses, blue = clothen tube.
so if you inflate the hoses there results a load on the clothen frame. on the outsides it`s no problem as the cloth takes up the load. the problem lies in the middle. there the mold has to take all the resulting load as there is no cloth that could hold the two parts of the mold together. so there is some sort of shear force in the molds itself.
version B shows the better way to do it. by adding some 2x6 or whatever on top and bottom of the mold you can take up those forces in the middle and pass them on onto the cloth frame. this should really reduce the shearforces in the mold and prevent it from snapping in two pieces.

but in general clothen pressframes are sweet. they can be a bit bitchy to load, but they are cheap, light and do their job pretty well.

...i think i should patent my great and glorious invention and start earning millions with it ;)
plywood freeride industries - go ply, ride wood!
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shopvac
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Post by shopvac »

The cloth press frame failed tonight. I was testing it out again at 40psi and it ripped apart. It didn't rip at the seam but it looks like it ripped on the top edge. The duck cloth will NOT work. I think we are going to abandon the cloth press frame idea and try and make a steel press. If you are going to try the cloth press frame in the future PLEASE use some other fabric and be very careful!

The cloth bags lasted for at least 24 hours and then they failed. I think with some of the I beam style presses the factor of safety was 2 to 4 times higher than what we were thinking of pressing. One of the major drawbacks of using the cloth bags is that we had no way of calculating the failure pressure.

When the bags ripped the molds bounced off the stand and came thundering down to the floor. Nobody was hurt. If we were to try and use fabric again we might look into some of the fabrics from soller composites. Maybe zylon or something really beefy.
voodoo
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What about nylon straps?

Post by voodoo »

I think if you used nylon straps maybe you'd be ok with your press.

Like the tiedown ones that you can tighten down.

They can take a couple hundred pounds of weight so if you have 6-9 you should be covered.
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MontuckyMadman
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Post by MontuckyMadman »

Hey, I'm reinventing myself here. I was Wannabebuilder.

But I built a ski.
It's just like a 138 similar to your pics..
I work in a shop that makes items from 1000 Denier Cordura nylon. I think it would be great as a press frame. Cordura is super strong. We have tons of remnant.
Like 2 and 3 yard sections of material 58" wide. It anyone wants this stuff I would be glad to donate.
Hell, I'll even sew the bag things if you want to gunea your self.
I would double line them I bet they could go to 70 psi.
Let me know
awesome skis shopvac
I will get mine up soon.
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shopvac
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Post by shopvac »

Well we were down for a little while but not out. Montuckymadman sent us some really nice double thick 1000 denier Cordura Nylon bags and we are back in business. We have a ski in the press right now. I am very eager to see how this ski turns out.

Just to fill everyone in, we had a double wide ski press with some duck cloth sewn bags until they ripped and the press fell apart. I think I know why the bags ripped. I had a pretty sharp corner and edge on one of the top "fill" boards that caused the bags to rip. Since it was only single layer and it was just a canvas fabric it couldn't handle the sharp corners. For anyone planning on using a cloth bag ski press frame in the future please make sure to put a nice round-over on any of the edges that the cloth will see. We have now done this and things are looking very good.

Since then we cut everything in half and now have two single ski presses. The new single ski press is a little bit of a pain because it is hard to get the top mold to sit straight. When we inflate the fire hose the top mold sits to one side or the other. We did get it pretty close to sitting flat but it took some work. Otherwise the bags work great. A huge thanks to Montukymadman for the quick help.

The ski we built today is 113mm underfoot with a 38m turn radius. It should be 192cm long and have 25cm or so of early tip rise. I think it will be really fun. The cores are made from pallets I recycled from work. I think the wood was a mixture of cherry (you can smell it), poplar, and oak. The cores were profiled to 1.7, 12.5, 2.3mm. We are pressing just over 40psi (maybe 42psi or so). We built in a little camber to this ski with a camber mold we made. I haven't measured what the expected camber should be but I am hoping for 5-9mm. We shall see. For this ski we also used the dowels through the core method for alignment. I am so impressed with this technique. We will surely be using this again in the future. Couldn't have been easier. One snip of the fiberglass with a pair of scissors and just pop the core right into place after that.

My brother looking at the base we just routed out:
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Edges are on, think we have enough $1 homedepot clamps?
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We did a 3/4 edge wrap again but for this second pair of skis we are making the edges go much closer to the end of the skis. I think this will be very helpful. The last pair had the edges end right where the tip and tail bends up.

We are using the white tip spacer material attached straight across the core with double sided carpet sticky tape. The tape looks like fiberglass with glue in it after the top paper is removed. This makes aligning the tip spacer really easy.
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The ski is in the press:
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I am still worried we are not going to get a good press in the tips and possibly in the tails. I think the yellow fire hose is still being allowed to inflate too much. This might be hurting the tip and tails. I hope they turn out better than last time. Should I put more fill material above the top mold (I already have the two 2x6's up there) to help reduce the airbags height which could help the press in the tips and tails?

The tips:
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I will post some pictures of the ski when it comes out of the press.
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