Core to Tip fill transition for snowboards

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n.marshall
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Core to Tip fill transition for snowboards

Post by n.marshall » Wed Mar 06, 2013 8:23 pm

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Unfortunately my friend Dain broke the tip on his splitboard last week. The nose became unhooked from his snowboard rack on his snowmachine, and the board was torqued and dragged up an icy groomer for a while before he noticed.

I hate seeing stuff broken, and it sucks that he wasn't snowboarding on it. But it just means that I will have to build it stronger next time. I am planning on laying up a new one sometime in the next couple of weeks.

This board has 19 oz glass to keep the weight down, I was thinking about going to 22 oz for more strength.

I was also considering cutting the core/tip fill line like voile's splitboards

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I also remember seeing in a lib tech layup video where the core was not a smooth arc, you can kind of see it here-

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What do you guys do for the core to tip fill transition? Any recommendations?

prospectsnow
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Post by prospectsnow » Wed Mar 06, 2013 9:07 pm

I think the transition is a real weak point.

I've seen a ton of boards start to crack where the tip fill meets the sidewall. In my opinion the ends of the effective edge take the most abuse so why put the transition there.

I started slanting my sidewall at the ends and meeting it with tip fill rather than perpendicular to the core. It helps? I haven't broken one yet.

Anyway. I think the possible weak point to that splitty is the straight line allows an excessive flex over the whole weak point (the joint) in a straight line.

I think making some curves and changing up the direction of the joint will cause the excessive force to distribute over a wider range of the glass fibers so the joint will be more durable.
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vinman
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Post by vinman » Thu Mar 07, 2013 4:27 am

I would agree that this straight line joint is a weak spot. An interlock style tip spacer would be much stronger. Some of our engendering folk might have some input on the strength of specific types of joints.

Although with the damage you describe anything might have broken, being dragged behind a sled like that.
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FigmentOriginal
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Post by FigmentOriginal » Thu Mar 07, 2013 5:12 am

I assume that is also where your sidewalls end. Sorry to see it broken.

A good reason to try pouring your own sidewalls like some of us do. IMHO the most durable sidewall material you can use, and totally customize-able with dyes/inks.

Here is an example of DTrain's split.
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twizzstyle
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Post by twizzstyle » Thu Mar 07, 2013 7:34 am

A straight joint is definitely the worst for a failure, a crack wants to propegate in a straight line, and this just helps that. But, it's also the quickest method, and that's why I do it on my skis, its a trade off.

I think you need more resin in your board, you can see a lot of the fiberglass. What pressure are you pressing at? Might be too much, too much squeeze out.

Also, why kind of tape is that holding the tip spacer in place? It kind of looks like masking tape. That may be a factor in this failure as well.

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vinman
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Post by vinman » Thu Mar 07, 2013 8:25 am

Twizz is right on as usual. For tape you want porous paper first aid tape.

To beef up your tip spacer joint you could also run some of your carbon across it in a few places.
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n.marshall
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Post by n.marshall » Sat Mar 09, 2013 9:44 pm

Thanks for all the suggestions.
twizzstyle wrote:A straight joint is definitely the worst for a failure, a crack wants to propegate in a straight line, and this just helps that. But, it's also the quickest method, and that's why I do it on my skis, its a trade off.
Yeah, same here. I have never had a problem with it breaking under normal use, but from now on I might start using a different method for durability.
twizzstyle wrote:I think you need more resin in your board, you can see a lot of the fiberglass. What pressure are you pressing at? Might be too much, too much squeeze out.

Also, why kind of tape is that holding the tip spacer in place? It kind of looks like masking tape. That may be a factor in this failure as well.
I press at 50 psi. I used less resin with Dain's board (the broken one) and more with Kyle's (the other board that is partially in the pictures). The carbon strip down the middle of Kyle's board shows a little bit of fiberglass as well. Both of the boards don't have a topsheet, only the top layer of fiberglass in order to reduce the overall weight. Could epoxy squeeze out be related to this as well?

I have been using masking tape, for the next couple boards I will try out first aid tape.

24Dave
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Post by 24Dave » Mon Mar 18, 2013 11:19 am

Why use a plastic tip filler in the first place? Your nose curve looks really shallow, gradual like it wouldn't be hard to press and have it stay.

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Post by Cornice » Wed Mar 20, 2013 10:44 pm

Think of masking tape like this... Its only as strong as the sticky stuff on it.
Glue usually will not penetrate under the sticky side so your bond here is only as strong as the tape.

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Post by skidesmond » Thu Mar 21, 2013 2:49 am

The straight edge joint (butt joint) is the weakest of all joints, in the wood working field. The epoxy will bond the butt joint and you also have the FG/epoxy that overlays both sides of the board bonding it altogether.

If the butt joint and the start of the tip/tail curve are at the same point that could weaken the joint. Also if the metal edge ends at the same point or very close to the same point as the butt joint that can be a weak point. You want to stagger those points.

As Twizz points out it's a trade off. I use a butt joint and I'venever had a failure. Tape s/b used only to secure the materials as a temporary measure until layup time. I tape on the outside so it gets cut off in the flashing.

Dragging it behind a snowmachine is not desirable, but it's a good stress test :D

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