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First wakeboard build

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freeskiwake
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First wakeboard build

Postby freeskiwake » Sun Aug 13, 2017 9:32 pm

Hello,
I am new to building boards and new to composites too, so I decided to build myself one wakeboard. Idea and materials came to me one year ago but did not make time to build board in summer 2016 I only made rocker table back then. I got some really good informations how to build the wakeboard from forum member Zob , so thanks a lot Zob ( that was one year ago.)

First things first I was searching forums for ski, and kite/wake board building for like 3 years now. I decided to buy paulownia cores and searched the internet. I found one company that specializes in making cores from paulownia like 40 mins away with the car. I got paulownia wood cores for wakeboard for fair price, when i got there forklift was lifting like 2 packets of paulownia cores (like 100cores) on the truck, serious business. :D I just got three of them.

My build plan is- Ptex 0.8mm, Woven 22oz Tri-axial Glass , paulownia core, Woven 22oz Tri-axial Glass, TPU/ABS Topsheet.

First I draw the board in drawing program and printed out the plan. Than I made a model of shape from paulownia wood. After shaping by hand i copied one core to another with router and copy router bit.
Image

Than I made heating chamber for attaching sidewalls to the core. Sidewalls bonded really well with the core. I sanded and heat treat them. One picture in the "oven".
Image

I made a planning table for the router. I managed to make the middle of the board 10,5mm thick and tips are 6,5mm. Took me a long time for precise routing.
Image

Than I sanded it by hand to get the smooth finish as you can see 1/3 of the board is sanded and other half is not.
Image

Then I routed out fin holes.
Image

After I poured pigmented epoxy in fin holes I made holes for inserts too. I poured epoxy with inserts in too.
Image

Than I made vacuum press together. I have vacuum tank and three fridge compressors, to run each for three hours ( safe backup). Rocker table i had from one year before. I set rocker to 12cm from middle to the top because I planned 50% spring back off the board. Firstly I laminated bottom of the board. One that picture ptex is secured in with a little bit of duct tape and fiberglass is all wet with epoxy.
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Everything went smooth and good ( for beginner), I was all hyped than worst fear came true. :( Here looks all fine in the press.
Image

Shock after 24hours of vacuum - 12hour was set on 50°C .Really frustrating. In 1second I lost all the motivation, I know that it is the first board and can not be perfect but why this happened. Thank god its not too much air gaped so it is still possible to ride it, but with bitter taste. How did that happen??? Board was laminated better then I expected only that 25cm of the board is total disaster (waves)??? Does anybody know why did that happen?
Image

But only the bottom was laminated and I ended with 100% right rocker of 6cm that i predicted. I was really stoked about that amount of rocker with only bottom side laminated. Is not the top side of the lamination the key to rocker not the bottom one? So why I ended with so much (really good) rocker??? :o
Image

Now I have two questions does anybody know why waves happened in the bottom side. I made a mistake and vacuum hose was pulling in much bubbles of epoxy and epoxy itself, didnt know that it will pump epoxy like crazy . It was pulling a lot of air from the epoxy is this normal? I tripple checked for any holes or leakage in the vacuum foil and didnt found any and pump was drawing good vacuum too... What i did wrong here? How to prevent epoxy from going into vacuum hose???

Other question is if I have now enough rocker with only bottom side laminated how to laminate the top side to not increase any of rocker??? Do I lower the rocker table to 6cm of rocker to fit the current state of board and laminate it like that and it will stay at 6cm? I have really no idea. I am afraid to put it back in in 12cm of rocker table and than i would get no needed more rocker or what? :D

I will try to finish the board and test ride it, hope that waves on bottom side do not have too much effect :x But still do not wanna to throw away my first board, I putted a lot of effort in it and I am learning and make mistakes.

Have a nice day!

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downunder
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Re: First wakeboard build

Postby downunder » Mon Aug 14, 2017 5:59 am

That is ok, don't be too harsh on yourself, you did a great job! I remember my first board, man, so much to learn :)

Basically, your sheet folded straight after you placed a core on it. I think that there is no way to control this with your setup unfortunately. This is coz the fabric on bottom is compressed and not tensioned as on top. See how this is not seen on the excess around the board? If can't be seen, can't be fixed, so no matter how much you checked anything else in my opinion.

This is the reason I never, ever glass the bottom on the rocker table. Others might have a different approach but I think with a vac, fabric can fold at any time, anywhere, typically in the middle.

To be fair, not sure where you picked up the info about glassing the bottom first?! Hope it wasn't Zob :) Glassing bottom first and leaving the top for latter will always crease your fabric. Really, it's it that simple. You control the board rocker with the top glassing, not bottom. The wood core board does not need a lot of glass for bottom, one can use 100 g/m^2 if the rider is light.

The Holly mantra of applying a top sheet(s) is a mechanical press. Zob is using a press if remember well.

I would suggest to try peeling it off before using. The board will take moisture in the creases.

D.

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Re: First wakeboard build

Postby freeskiwake » Mon Aug 14, 2017 6:31 am

Oh I see I screwed up :-?

So now there is no good to try laminating now the topsheet on the board? By peeling it off you mean peeling off the whole FG and ptex from the bottom and do it again? wrinkles in the board are on the sides good impregnated with the epoxy? Will moisture entre the board even when epoxy is quite well in the place of sidewalls where waves are?

I was planning to just try laminating FG and topsheet on rocker table now adjusted to 6cm this would not work? :roll: and try the board out even with waves maybe it can be called waveboard :P

I am using 3M halfmask with filter for organic vapours and dust filter too when cutting and sanding FG and ski googles alike 3M clear goggles. Now i have a question how do you get fibres from the clothes when cutting and sanding FG, or its time to just throw away that clothes???

Have a nice day.

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downunder
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Re: First wakeboard build

Postby downunder » Mon Aug 14, 2017 6:59 am

On compression (actually, board tension) this wavy FG/sheet might crack, no matter if the void is filled well near the rails. Even worse, on first jump, the board might break on exactly that spot.

To prove this, try to compress the void with something, apply good force. If even slightly cracks, that's it. Hence, I would peel it off completely, with a spatula or something. Did that on one core quite successfully. A lot of work, but hate to bin a good core.

Only water sanding FG/carbon. Loose fiber just vacuum.

D.

PS

I see you did the straps inserts half through. That is not good. The force on inserts is brutal. In my view, not only that they need to go all the way, but the SS inserts need to be reinforced with a bit of FG so they resisting pulling out and staying put. Basically, this is the weak point coz all inserts holes are in the same line, no much 'meat' on wood for inserts to 'bite' in. By inserts I mean a proper SS inserts, not epoxy. You can find them here.

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Re: First wakeboard build

Postby rynhardt » Mon Aug 14, 2017 10:07 am

First of all, congrats on your progress so far! There are many little gotcha's on the road to success, don't give up!
It really is worth it to test your process on scrap pieces before committing a full board. Even then, shit sometimes happens.

Your core looks really good. It may be worthwhile sanding off the wavy bits and re-laminating it. You could even just do a normal wet layup without vacuum if you are happy with the rocker.
For sanding fibreglass, I recommend buying cheap overalls and then either keeping them solely for sanding fibreglass again or throw them away.

Working with vacuum can be tricky. We use an infusion resin and then degas the resin at higher vacuum than the actual infusion. Otherwise the resin will outgas and form bubbles. We then do a 24 hour post-cure at room temperature, before doing the elevated temp cure. Once again, this prevents bubbles forming due to the resin outgassing from cooking.

Good luck!

freeskiwake
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Re: First wakeboard build

Postby freeskiwake » Mon Aug 14, 2017 12:00 pm

What do you mean with sanding off wavy bits to just send off to the core 25cm of the board an re-laminate just that piece? I dont wanna to rip off whole stuff off and sand it down, I think I will ruin the core that way.

So I am more interested to just wet layup the top side of the board. So by that u mean to just roll on the FG and put topsheet on and just cure it in heat chamber? And ofcourse try with hand and roller to put as many air as possible from the top side?

I have SS inserts in epoxy can I reinforce it with FG straps like shown on the photo? Is this good idea?
Image

So do you think its good idea to just wet lay up upper board with FG reinforcement, FG and topsheet, and hope for the best and try not to brake the board. Really dont wanna to ruin the core with pulling off whole lamination... :(

Thanks for the answers.

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Re: First wakeboard build

Postby downunder » Tue Aug 15, 2017 3:26 am

I don't think it can be sanded off and re glassed coz it is the top sheet you have at the bottom, right?

If you still have some excess FG pieces you've cut around the board than you might test with this pieces if it can be peeled off. Glue some pieces asap on similar wood and try. Maybe even preheat a bit, to soften epoxy before peeling. Duno.

The problem is, as I see it, your board will go completely flat very soon since nothing is resisting a springback at the moment. The above pic is showing plain wood, meaning the moisture is slowly building from the air humidity causing wood to expand, making the board flat. You need to seal the top with epoxy sealer asap (good) OR fiberglass the top asap (better), with no topsheet on top (waste, better use next time).

Placing the FG in red squares reinforces the area, not the inserts. You can read more in here (Lex comments):

http://boardbuilders-forum.1077691.n5.n ... .html#a204

"WARNING to all those building boards. Do not skimp on the reinforcements under and over your inserts. After being hit by a wave one of my foot strap inserts tore out. this was easily fixed with some sanding and carbon but could of been avoided in the layup. I also recommend reinforcing underneath the inserts. when the screw is pulled up tight it can lift the inserts slightly causing a divet in the underside of the board. Using a carbon or glass cloth under the inserts you can spread the load from the screw keeping your boards underside nice and smooth."

The above forum is btw full of good tips and how to's.

D.

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Re: First wakeboard build

Postby freeskiwake » Tue Aug 15, 2017 6:42 am

Hello,
I tested to FG and topsheet the upper board, because no point to fix bottom of the board and screw up on topsheet.

I didnt see so much air trapped in when vacuum was applied, I pulled vacuum for two hours and then i rised the temp. Maybe because of rised temp air expanded in board. Now only one pair inserts is rideable. I learned a lot and this is it from me for this year. As I see vacuum is maybe not the best for closing FG with some plastic like topsheet. To build boards like this with topsheet and Ptex its a must to invest in pneumatic press, correct me if I am wrong because I am just a beginner and thats my point off view. :wink: . I am not sad or something like that because board didnt turn up too good. But still I hope I will make some runs on cable. Maybe I will build pneumatic press for the next year, will see who knows. :D .

Image

Will report how cutting the board out, sanding and than binding mounting went :wink:

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Re: First wakeboard build

Postby faklord » Tue Aug 15, 2017 7:46 am

Maybe sealing the core (with epoxy) before applying the top sheet would prevent air from being pulled out of the wood core?

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Re: First wakeboard build

Postby downunder » Tue Aug 15, 2017 8:11 am

^
I wish it's that simple. Unfortunately it is not. There were a number of ideas over the time, one is to infuse a resin under the topsheet between the core. Some other would be to heat a core (rocker table) and resin slightly, to help with viscosity.
But nothing comes even close to a mechanical (pneumatic) press. Also, the pressure is immense, like 80-100Psi which is way way more than a full vacuum. The air that way is squeezed out, coz that is how the press works with a huge bladder pressing the board on 'cassette' which builds the rocker/channels/etc.

The vac is not squeezing out anything. When we breath in, do we squeeze lungs? ;) Or when you breath out? Simplistic example, but yeah...


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