:: View topic - The bangers & mash

Kelvin.... Great looking skis. Looking forward to seeing the dimensions & the intended use/improvement description!

these skis are amazing. they skied great:

http://www.skibuilders.com/gallery/bangers.shtml

Not made in China.

Made by chinese.

Broke in on China Mtn.

I love it !

I'd be interested to hear you comments on a couple of things.....

Can you appreciate any performance improvement from the addition of carbon fiber? Was it a bi-axial mat?

I noticed that you didn't bother with ABS side walls. My assumption is that since ski dimensions and construction techniques are a work in progress and the skis aren't getting enough skier days to warrant the extra time and expense of the ABS or UHMW sidewall. Will you be using the plastic sidewalls in the future?

We've made a bunch of skis with wood (maple and poplar) sidewalls and they hold up really well. I tend to ski with my feet too close together and the insides of my skis get beat up as a result. The wood sidewalls have taken a beating and they don't look much worse than the skis with abs sides. If you want them to last years and years, I would varnish/seal them every so often and make sure you dry them after use. Bottom line: They are much quicker to make and seem to be durable.

-kelvin

hose-man.

we used the CF to stiffen the ski. the core thickness was 10.5mm underfoot. some of our other skis of the same shape had slightly thicker cores, between 11-12.5mm. by adding the CF, we were able to reduce the wood core thickness slightly. to be honest for the Bangers, a core thickness of 10mm would have been more ideal, but they are amazingly fun to ski. the 25m radius sidecut makes then very versatile.

the CF fibers were only in one direction...along the length of the ski.

In your opinion do you prefer the carbon fiber or titinal for extra snap/reinforcement. What are the advantages of each? Maybe I missed this earlier, but did you use carbon fiber tape (i.e. 2 inch width) or did you trim a larger roll of carbon fiber to your dimensions.

By the way I love the solid color graphics.

Titanal doesn't really add pop, it works more in dampening or smoothing out the ride. I use it on my highest end boards & results have been great. You have to be careful how much you use though or you'll have a really smooth ride with no pop. I use carbon to add pop, but for the big mtn/hard charging ride I go without the carbon

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so, we pressed pair number two a few weeks ago and had a lot more success than our first pair, but still a few problems.

1. We pressed our skis for 26hours at a declining pressure of 40-25psi overnight. We pulled the skis which immediately lost almost all camber, and about half of the tip and tail rise. I am stumped why this happened, all I can come up with is that it is the epoxy. we used west systems 206A and 205A just like you guys, although the temp was around 40* by morning (the epoxy should cure in 10hrs or so at 32 though? ? ? ?) any ideas?

2. Skis were SUPER SOFT---understandable since we used 4oz glass and hemlock cores (unlaminated)---these were our lower benchmark skis to see what a minimum amount would ski like (min. glass, soft wood, two layers glass per ski, nothing fancy) my question here is this: wil doubling mass of glass double stiffness? (ie two layers of 8oz glass?)

3. BIGGEST PROBLEM! we mounted some alpine bindings (look p 8.0 demo). The toe piece ripped out after one semi-aggressive run in th BC in soft snow, stripped right out of the wood. Some ski shops told me ALL skis use metal sheets for the binding to screw into, i dont believe them, what do you recommend? (thicker/more layers of glass under-foot, perhaps some glass matte?)

4. Bases were concave and convex all over!, I took them to a ski shop, and in order to get them flat, they took off so much base that it was non-existent in some areas---what cause such a thing? (epoxy buildup, glass crinkles, MDF ribs?????)

Thanks for any help

2. 4oz glass seems too few. Usaully people uses 20/30 oz./sq.yd.

If you double the glass it will much more than twice stiffer. If I remeber well the stiffness is proportional to the cube (maybe only the square) of the glass layer.

3. I do not think you need metal sheet: a thick strong wood core would keep the screws.

4. Base can be slightly concave or convex, but just few tens of mm. Is the core smooth? Did you lay down the glass flat? Check maybe the press.

I would suggest you do some trails, laminating a wood slab (maybe 10cm wide, 50cm long) with glass and a piece of base, just to get more experience. Then you can use these pieces to make flex tests, so you can learn how much glass you need to get a certain stiffness.

1.) In our unheated press, the skis will probably lose half the camber. If you want 10mm of camber in the final ski, your mold should be about 20mm. I'm assuming you meant 105 resin and 206 hardner. The 206 is there slow hardner and they recommend 60f minimum, the 205 hardner is faster and works to 40f. Even at those temps 206 takes about 9-12 hours to become solid and 1 -4 days to reach full strength. If you are working in cold temps you should use 205.

2.) More fiberglass would probably stiffen it up, but a thicker core would stiffen it up more. Another problem could be your epoxy not fully cured.

3.) Hemlock is a softwood and isn't very strong. It is pretty similar in strength to pine. You probably want to use a hardwood that is dense and strong, like maple or birch, especially where the bindings attach. Not all skis have metal and I think a nice chunk of hardwood would hold a screw better than a thin sheet of metal or extra fiberglass.

4.) Check your mold, core, and layup to make sure everything is smooth to begin with. It is possible that your mold or press is not stiff enough and is deforming with pressure.

Send some pics if you can. thanks.

-kelvin

I mount alpine bindings straight into the skis, without a metal binding sheet, and I have only had one screw pull out (I drilled the hole oversized though, so it was to be expected), I have not mounted with softwoods though (just maple, ash, and mahogony). One trick you can do is to load up the mounting holes with glue before you screw the screws in. This really helps keep everything together. Other than that, all of my bindings have stayed on really tight, and I am extremely tough on my skis.

What I have found though is that the easiest way to delam a ski is to spend time in the terrain park. The hard landings on the jumps really can do a number on your tips and their lamination (I think rivets should solve this problem though).

its the hemlock that has no stiffness or ability to hold a screw. I come from the northeast usa originally, where the best "hardwoods" from. (yes, I know the northwest has nice softwood lumber species) hemlock is considered useless back east, it not good for woodwork, doesn't burn worth a damn, and will find any pipe underground carrying any water and bust into it with very powerful roots. I assume you are looking for a medium stiff ski from what I have read here so far. most ring porous species are very stiff, ash, oak, hickory,... etc. From what I have read here so far these would be suited for old style double camber type ski's unless you were going to make a thin ski and take camber power out of it by thinning the ski height. I see here the ski makers talking about poplar and maple mostly and I would think that would make a good core strong enough to not tear a binding out and stiff enough to hold some camber too.