I'm new around the forums, and I have a question.
I'm not going to build skis, but I am looking to build some snowboards.
I would like opinions on using polycarbonate for a core.
How can delamination be prevented?
I know the core will need some kind of longitudinal stringers to take out some flex.
Anyone??
James L
Welcome! About half of the folks on here build boards, don't worry it's not just ski building!
What is the reason you want to use polycarbonate?? Are you talking about the clear stuff that is heat mold able? Because good luck bonding that to anything. I've used it as a mold surface before (non ski project)
Why polycarbonate?
I've never done any gluing with polycarbonate, however curbell plastics mentions that, with at least the material they sell, its bondable, which i find rather surprising
-Jacob
Well, I figure it is easily obtainable, and can be recycled.
Also, the board would be almost indestructible.
Yes, I'm talking about polycarbonate sheet, like Lexan, but I would probably use some other brand to save money.
James
Well I've certainly never heard of anybody doing it, you'll probably have to do a few test pieces to figure out the stiffness, thickness, and weight. Seems like it would be incredibly heavy?
Yes, I do plan on testing, if I can overcome the lamination issues.
It probably will be heavier than a standard wood core. I hadn't thought of that. But the possibilities would be cool.
James
Just as a follow up:
I did some calculations, and the core would weigh: 5.66 lbs
I'm not sure, but that sounds very heavy for a core. I didn't calculate in the holes for the inserts, but the weight saved there wouldn't be much.
James L
It does sound very heavy, i belive my complete boards weight less than that
If you or someone else has a core, a weight would be nice for comparison.
James
figure 8-10 lbs per pair of finished skis depending on your core choice and composite and epoxy and pressing.
an acrylic core would also be very brittle, i would think.
Im sure its elongation at break is significantly less than say ash.
I'm working with a snow board, but I understand your reference.
But to correct the brittle issue: I was discussing polycarbonate, not acrylic. They are worlds apart. Polycarbonate @ 3/8 is bullet proof. I shot a 12 x 12 piece of polycarbonate (0.375 in) with a 357 magnum, and it stopped all five rounds. It was less than 6 feet away. It probably wouldn't stop a shot gun slug or a 50 cal. It is far from brittle. I have actually tied 1/8 inch poly in a knot.
The idea here is to have a board which would be very tough. I probably wouldn't even use a top sheet, and use cap construction. That would lighten the board a lot.
Also....I have found a PDF which says 80 grit sanding before bonding is all that is needed.
James
Sounds like some testing is in order. I say lay up some material and run some tests. It may bond ok but wonder how well it stays bonded after repeated flexing and twisting. Also put your sample in a freezer or outside on a cold day, then flex. See if it becomes brittle or delams.
I guess that is all I can do. I'll just go for it, when I get ready.
I have some other testing I must do before getting deep into the poly test.
Thanks for the idea, of the freezer or cold day. That would definitely be a good idea. I don't want the board to delaminate while I'm riding it.
James
Yeah will certainly be interesting so go for it!
But I'm not sure you need to worry about having a bulletproof board, what kind of scary mountain do you ride at? Doesn't seem to common that cores are the weak part of a ski/board (I say that, while I just had a core failure on a ski...
But that was my fault for using the wrong kind of bamboo)
Actually, it's all about clear, not bullet proof. I'll just leave it at that.
I'm just thinking about options, and possibilities.
Can I ask, where you got the bamboo?
James
I get my bamboo from a place called Bamboo Hardwoods in Seattle. It is just bamboo flooring boards. The issue I had was I used horizontal grain bamboo on a pair, and the middle layer of the boards had the grain running laterally, and it was a very loose grain with lots of gaps. I landed hard on the tails a few weeks ago, and that middle layer of bamboo ripped apart just behind my heel binding. Lesson learned - vertical grain bamboo only!
I'll just throw out some of my experience working with polycarbonate (PC). For my job we had an application where we had to bond several different types of materials to the PC. We tried several types of plastics and foils. Not much would work well to get a durable bond. We tried UV curable adhesives, silicone based glues, etc. None would bond well unless the surface of the PC was textured. This allowed the adhesive to create a sort of mechanical bond to the surface of the materials being joined (similar to applying teflon to a cooking pan, or better yet, think of velcro except on a microscopic scale).
However, as soon as the parts were flexed the components started to fail and separate. The only thing that seemed to work was plasma treating each surface with argon to change the surface energy. Then we held them together in a fixture and applied heat. Afterwards we couldn't pull them apart. The plasma treating was extremely finicky though. It took a lot of work to get it just right.
The take away from all this is, you may get it to bond, but I would be a little skeptical having it strapped to my feet when dropping into a couloir or something. To be fair we were using only a few grades of PC and there are tons of different flavors out there so maybe it will work. I totally think you should test it and see if it survives flexing. Do your research or call the companies and find a PC that has good bondability.
Thanks for the insight.
I was actually going to try a miniature version of a snow board without the edges with the same layup. This would tell me if it could be done.
The flexing is ultimately the test of the bonding.
James
