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Cap vs sandwich construction


Dr D

Which is better and why  

54 members have voted

  1. 1. Which is better and why

    • CAP construction
      5
    • Sandwich construction
      38
    • Combo
      1
    • could give 2 ****s
      10


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IS it all hype? I know several builders who use cap exclusively for specific reasons. I also know that big snowboard company X says that cap= cheap junk.

The Dynastar legend is sandwich between the bindings and cap on both nose and tail with exceptional results.

what is your opinion and why.

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is that the cap boards have owned in the past and presently own are snappy and lively,but not as damp as the sandwhich boards in my past and present.It seems to me that a cap also may limit the precision with which ride characteristics can be designed into a board.I know that durability has been an issue for some riders on caps but I have yet to experience a difference.I am more likely to think that core construction has a greater effect on durability than whether a board is cap or sandwhich.But hey,I could be wrong...

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makes sense to me. John builds cap boards because they are livelier and because he can make them all the same easier. I guess the cross thing with the legend is that the dampness is in between the feet and the nose and tail are more alive.

John did say that mass producing cap boards is harder to control quality. they have to be exactly right in the press. I have yet to find an identity or garage that I didn't love. they are all cap construction. I really liked the dynastar legend as well but found it to be really heavy.

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IS it all hype? I know several builders who use cap exclusively for specific reasons. I also know that big snowboard company X says that cap= cheap junk.

The Dynastar legend is sandwich between the bindings and cap on both nose and tail with exceptional results.

what is your opinion and why.

caps are cheaper, this is the reason caps were first produced and this is the reason the vast majority of the low end skis and boards are capped but fairly few of the high end boards

That information was given to me by someone that was at solomon and also others in the industry have said it.

they are also harder to repair and tend to more failures that will kill the plank, the vendors like this idea as long as it happens after warranty

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Edge damage is more likely to be unrepairable on the cap,

I think combo like Rossi's dualtech would have the benefits of both.

He nailed it on the head.

This is the reason why I avoid caps at all cost. They're just a pain in the ass, since damages are inevitable and -will- happen one way or another.

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what edge damage specifically. I notice cosmetic stuff from lift lline etc that needed a little epoxy to seal. you cant shave sidewall after one to many base jobs as effectively. I have used epoxy and or super glue on the cap edge and sidewall of both types equally. Are we talking about serious damage like a delam?

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My preference is sandwich. I like the ride better and they are more durable to side impacts.

I currently have to fix a blown edge on my Tanker 200. A cap board would have been demolished with the force of the impact with a tree that my Tanker took.

A true cap board, with a structural cap, may have some significant benefits but most are lower end production to save a buck.

I will say that I do also like my Dualtec Rossi and make every effort to not cause damage near the edges.

Ink

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so maybe the structural cap thing is where the meat of this subject lies.

I am familiar only with structural cap. (My cap boards are tougher than my sandwhich boards) I never realized that there are differences under the cap. The indentities and garages are sandwhich that extends beyond the core and is trimmed to meet the edge after pressing. The topsheet and the fabric both cover down over the radiused core to the edge. Barring massive trauma thats as tough as a board gets. carbon and aramid fibers or even fiberglass trilam is tougher than a thin layer of plastic.

Now if you just layered the graphic topsheet down over the edge It would be a cheap piece of ****. I guess I never ran across one built that way.

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the board is thinner toward the edge and so if you blow out an edge there is less material to anchor to in that area. also, if the cap is structural (like salomon) once you have cracked it at the edge you have compromised the structure of the cap and you have a likely failure point...or so I hear...

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so really it comes down to core design and how well made the cap is as well as how thick the edge material is. I notice a huge difference between our handmade customs and the run of the mill boards in edge thickness. the metal edge on my garage is easily 2.5 times thicker than the edges on the dynastar legend I had. 3+ base grinds vs maybe one. thats gotta have more effect on board strength than a core thats radiused on the top edge.

I am no engineer but I like to think I can objectively look at the physics of something. having a flat sheet of fiber (triaxial lets say) lined up against something that has at least one bend in it or a radiused curve, the bent piece should be stronger and certainly stiffer(ie the above mentioned livliness)

I can see the cracked edge thing being a weak point but epoxy will seal a crack on a cap as easily as it does a crack on a sandwhich.

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so really it comes down to core design and how well made the cap is as well as how thick the edge material is. I notice a huge difference between our handmade customs and the run of the mill boards in edge thickness. the metal edge on my garage is easily 2.5 times thicker than the edges on the dynastar legend I had. 3+ base grinds vs maybe one. thats gotta have more effect on board strength than a core thats radiused on the top edge.

I am no engineer but I like to think I can objectively look at the physics of something. having a flat sheet of fiber (triaxial lets say) lined up against something that has at least one bend in it or a radiused curve, the bent piece should be stronger and certainly stiffer(ie the above mentioned livliness)

Kind of......

You can thank "the jibbers" for thicker edges. The standard has increased due to the market of these guys needing burly edges. Before them, it was all pretty standard (thin).

The biggest factor in board flex characteristics is the thickness of the core. i.e. the distance between the composite layers. The next is the thickness of the composite layers themselves. The composites charateristics make up the "characteristics" of the ride. In the FEA models I have seen/done, cap vs. sandwich have basically the same numbers given all variables alike (except for the sidewalls). This is WAY simplified, but pretty close.

If you REALLY want to know...... There is a really good book: http://www.amazon.com/Physics-Skiing-Triple-Point/dp/1563963191

Check it out!

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so maybe the structural cap thing is where the meat of this subject lies.

I am familiar only with structural cap. (My cap boards are tougher than my sandwhich boards) I never realized that there are differences under the cap. The indentities and garages are sandwhich that extends beyond the core and is trimmed to meet the edge after pressing. The topsheet and the fabric both cover down over the radiused core to the edge. Barring massive trauma thats as tough as a board gets. carbon and aramid fibers or even fiberglass trilam is tougher than a thin layer of plastic.

Now if you just layered the graphic topsheet down over the edge It would be a cheap piece of ****. I guess I never ran across one built that way.

It's not about the strength of the fibers as much as the brittle behavior of the epoxy matrix. If you've ever purchased a fiberglass motorcycle helmet, you've been told that dropping it on pavement once will render it useless. The same holds true for a cap construction snowboard. Hitting a rock once fractures the epoxy matrix above the edge. It's unlikely that you'll even see the damage, but it's there. The cracks will wick moisture which freezes and thaws as you go up and down the mountain. Every time it does so, the crack is widened. The board becomes weaker and weaker with time in that area and that one little tap on a rock becomes the eventual destruction of the board.

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makes sense to a point.

why wouldn't a sandwich board do the same thing? same materials. I understand that the sidewall material has a certain elasticity to it that would mediate an edge strike somewhat. The epoxies used would seem to be a bigger factor. certainly snowboard epoxies are more resilient than the stuff used in helmets. Helmets aren't designed to flex rapidly back and forth for extended periods of time.

Careful maintainance and profilactic epoxy applied to even minute cracks would be a good idea then?

As a manufacturer could you honestly say there is a dramatic difference in the two? assuming we are talking about two boards of the same quality otherwise.

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makes sense to a point.

why wouldn't a sandwich board do the same thing? same materials. I understand that the sidewall material has a certain elasticity to it that would mediate an edge strike somewhat. The epoxies used would seem to be a bigger factor. certainly snowboard epoxies are more resilient than the stuff used in helmets. Helmets aren't designed to flex rapidly back and forth for extended periods of time.

Careful maintainance and profilactic epoxy applied to even minute cracks would be a good idea then?

As a manufacturer could you honestly say there is a dramatic difference in the two? assuming we are talking about two boards of the same quality otherwise.

Brittle fracture is directly related to thickness. This is why a glass fiber can be tied in a knot, but a pane of glass shatters if you bend it. Cap construction incorporates a verticle fiberglass laminate component, effectively making the fiberglass laminate as much as 10 times thicker at the sidewall. Stress varies as a cube of the thickness. Stresses from impacts in thin laminates are relatively small, but at 10 time the thickness, you've increased the stresses as much as 1000 times. This is a dramatic increase in the likelyhood of brittle failure.

I've only seen one cap construction that addressed this issue effectively and that company is out of business. As a result I'm unaware of a cap construction currently on the market that could be compared to a sandwich construction from a durability standpoint.

The next issue for this community really is cost effectiveness in a small market. Cap construction is a component and labor saving assembly process that requires substantial capital investment in tooling. Given the size and fickle nature of the alpine market it is difficult to offset that tooling cost on a very small run of boards.

There are techniques for pressing cap without the tooling, but they have significant drawbacks when it comes to consistency and quality control. It would be extremely difficult to produce a one off cap construction board and then reproduce the exact same result a week, month or year later. With sandwich construction it is possible to duplicate results time and again without the tooling expenses. From and economic and consistency standpoint sandwich construction is vastly superior in a custom market.

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excellent thank you. any qualms telling me which now defunct company had it figured out? I can definitely see your small custom shop tooling cost point. We have a hard time getting jon to get on board with new ideas for that very reason.

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excellent thank you. any qualms telling me which now defunct company had it figured out? I can definitely see your small custom shop tooling cost point. We have a hard time getting jon to get on board with new ideas for that very reason.

John who? Is it John Carpenter? He called it a radiator cap. I think Scottybob still uses that technology.

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more than saying which one is better and why, he explains why different companies choose one or the other for different reason, i would hate to demo a board, like it, order one, and end up with a different board then the one i tried

The next issue for this community really is cost effectiveness in a small market. Cap construction is a component and labor saving assembly process that requires substantial capital investment in tooling. Given the size and fickle nature of the alpine market it is difficult to offset that tooling cost on a very small run of boards.

There are techniques for pressing cap without the tooling, but they have significant drawbacks when it comes to consistency and quality control. It would be extremely difficult to produce a one off cap construction board and then reproduce the exact same result a week, month or year later. With sandwich construction it is possible to duplicate results time and again without the tooling expenses. From and economic and consistency standpoint sandwich construction is vastly superior in a custom market.

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