Contact   Imprint   Advertising   Guidelines

Concave questions

Here you can exchange your experience and datas about your home build boards
TheJoe
Very Frequent Poster
Posts: 1735
Joined: Fri Oct 30, 2009 9:13 pm
Local Beach: Texas city levee, Galveston, El Jardine and Crystal beach.
Style: Freeride, Foil, Surf, a lil freestyle
Gear: North Reach 7,9,12
Brunotti TT
Moses 633/483
Dwarfcraft Micro
Brand Affiliation: None
Has thanked: 9 times
Been thanked: 117 times

Re: Concave questions

Postby TheJoe » Thu Apr 14, 2016 4:41 am

Not really good to look a the process of a production board. They are done on presses and heat cured so they can pump out a volume of boards. The board blanks are cnc machined and then put in a thick metal mold, pressed at thousands of pounds then heated.

I would start off with simple builds and figure out your process to making boards.

alex85
Frequent Poster
Posts: 215
Joined: Thu Nov 25, 2010 12:41 pm
Kiting since: 2005
Local Beach: Rimini , italy
Favorite Beaches: Every where is sunny and windy
Style: 50% OLDSCHOOL 50% NEWSCHOOL
Gear: Slingshot Turbine 15 2018
North Vegas 13 2016
Dutonce Dice SLS 12 2023
North Vegas 10 2016
Duotone Dice SLS 10 2022
Duotone Vegas 9 2019
Dutone Dice SLS 8 2022
Slingshot RPM 7 2020
Duotone EVO 7 2023
Ozone Torque 136x41
Brand Affiliation: None
Has thanked: 18 times
Been thanked: 19 times

Re: Concave questions

Postby alex85 » Fri Apr 15, 2016 12:25 pm

Thinking better I understand it's not so easy.... :-?

I Will Start without!!!!

TomW
Very Frequent Poster
Posts: 3585
Joined: Wed Oct 05, 2005 6:43 pm
Kiting since: 2001
Local Beach: Vejbystrand, Lomma
Gear: TW Surfboards hydrofoil board 110
Gong Veloce M, 100cm carbon mast
Ozone Hyperlink V1 7m
Hyperlink V2 9m, 13m
Concept Air Wave 4,5m
Brand Affiliation: None
Location: Sweden
Has thanked: 53 times
Been thanked: 193 times

Re: Concave questions

Postby TomW » Sun Apr 17, 2016 3:10 pm

I built my first TT back in 2002 and it turned out pretty good. What I did was buy a 10mm thick price if 80 kg/m3 closed cell foam. In this case Divinycell H80. Pretty easy to work with.
Then I cut N shaped outline, tapered thickness on ends, tips, shaped channels on bottom. Had big center channel through whole length , and dual channels in tips. Used sanding blocks.

Then I put plastic t shaped pins in center of board from deck ( flush on deck) and put blank on sawhorses, and added weights hanging from pins. Drilled holes in pins and had a bucket with rocks in it tied to pins. By adjusting sawhorses position and weight I got rocker I wanted. You could get detailed and have 2 pins a bit out from center and get more parabolic rocker. But constant rocker is still good solution. Then I laminated deck like a surfboard. If you add carbon fiber to deck you can add flex and stiffness you want. ( I didn't do that just used 2 or 3 x6 oz glass). When board cured a removed pins but just cutting off at bottom. Very very little spring back. Glass is good at holding tension.
Then glassed bottom. Wrapped the rails surfboard style. They were a bit rounded to allow glass to go round.
Forgot to say before glassing I routed out foam all rather way thru where fins would go and cast solid epoxy in.

After glassing To get sharper rail I taped off rails to create dam, and poured in epoxy then sanded sharp. Painted whole board with 2 component polyurethane.

It was great beginner board! Sold it a year later and that paid for the materials.

You could do same thing with thinner wood core if you can find paulonia or balsa wood. Be more work to carve channels but not impossible with router, sharp tools. Have to consider spring back.
It's even possible to glue up strips of balsa to a blank.

Alternative to wrapping rails like surfboard is to route a channel in foam or wood that is almost entire depth, and outside of channel is outline form. Use a template to route. Then fill with epoxy this gives solid rail, cut off foam on outside, do above and glass only top and bottom surfaces and Sand to epoxy edge.

Give it a go man! Making stuff is fun.

plummet
Very Frequent Poster
Posts: 6819
Joined: Sat Aug 29, 2009 11:25 pm
Local Beach: EE
Favorite Beaches: NZ
Style: Terrain riding
Gear: Old wornout ozone.
Plummet hydrofoil and mutant
Brand Affiliation: None
Has thanked: 11 times
Been thanked: 224 times

Re: Concave questions

Postby plummet » Sun Apr 17, 2016 7:57 pm

The more rocker you have the smoother the ride. However the less efficient the board and the worse upwind you go. One of the things you can do to counteract the loss of efficiency when adding rocker is to add concave.
This will flatten out the rocker across the waterline. Making it more efficient yet still smoother than a non less rockered board.

Want a graphic example of this? Find a mako, get a straight edge and slap it across the waterline. Its dead flat. The board is highly rockered and has huge concave. Its a really efficient board for its shape.

User avatar
sabraxas
Frequent Poster
Posts: 269
Joined: Fri Nov 19, 2004 11:40 am
Has thanked: 0
Been thanked: 0

Re: Concave questions

Postby sabraxas » Tue Aug 09, 2016 2:28 pm

Concave. See it by yourself.

Image

Image

Once i began with massive concaves, i never left them.

Image

User avatar
downunder
Very Frequent Poster
Posts: 2811
Joined: Mon Jul 01, 2013 7:16 am
Gear: building my own
Brand Affiliation: None
Location: Perth, Australia
Has thanked: 153 times
Been thanked: 160 times

Re: Concave questions

Postby downunder » Thu Aug 11, 2016 5:38 am

sabraxas wrote:Concave. See it by yourself.

Image

Image

This is proving what exactly? :) Let's face it, if your board is not flat on top or if not using thick and fatty footpads on a heel side, one would need to edge really hard comparing to the flat board. Putting a lot on fatigue on legs, resulting in a shorter session for me.

The art is to find a right amount of concave for the user. The right flex for the user. Etc...

User avatar
sabraxas
Frequent Poster
Posts: 269
Joined: Fri Nov 19, 2004 11:40 am
Has thanked: 0
Been thanked: 0

Re: Concave questions

Postby sabraxas » Thu Aug 11, 2016 9:55 am

downunder wrote:
This is proving what exactly? :) Let's face it, if your board is not flat on top or if not using thick and fatty footpads on a heel side, one would need to edge really hard comparing to the flat board. Putting a lot on fatigue on legs, resulting in a shorter session for me.
You can draw your own theorical conclusions.
True is that massive concave with proper outline shape is totally the opposite of what you are saying.

have you ever tested a Mako?
You should.

I never believed in concave until i built a similar mako kiteboard with 2 cms of concave. I loved it. Great upwind, super fast, choppy killer, massive carving turns, no fatigue on legs, soft ride, nice in waves.

Why? Why?

A friend of mine, surfboard shaper, put a spoon and a flat surface under waterjet.
The spoon redirected the flow of water. The flat surface didnt in the same way.

"See this?", He told me. "Here is your answer"


Image

Image

User avatar
downunder
Very Frequent Poster
Posts: 2811
Joined: Mon Jul 01, 2013 7:16 am
Gear: building my own
Brand Affiliation: None
Location: Perth, Australia
Has thanked: 153 times
Been thanked: 160 times

Re: Concave questions

Postby downunder » Thu Aug 11, 2016 10:28 am

sabraxas wrote:
downunder wrote:
This is proving what exactly? :) Let's face it, if your board is not flat on top or if not using thick and fatty footpads on a heel side, one would need to edge really hard comparing to the flat board. Putting a lot on fatigue on legs, resulting in a shorter session for me.
You can draw your own theorical conclusions.
True is that massive concave with proper outline shape is totally the opposite of what you are saying.

have you ever tested a Mako?
You should.

I never believed in concave until i built a similar mako kiteboard with 2 cms of concave. I loved it. Massive upwind, super fast, choppy eater, massive turns, no fatigue on legs, nice in waves.

Why? Why?

A friend of mine, surfboard shaper, put a spoon and a flat surface under waterjet.
The spoon redirected the flow of water. The flat surface didnt in the same way.

"See this?", He told me. "Here is your answer"
Why do you think I did not? Used to own a 1.5cm concave board and hated it. It was that rigid. The more concave built in, the more rigid the board is. No brainer here.

Not for everyone's taste. If you like it, fine, I don't. I ride 120/39cm board 99% of my time, would you like it? Highly doubt that. I am 59 kg, figure out...

User avatar
sabraxas
Frequent Poster
Posts: 269
Joined: Fri Nov 19, 2004 11:40 am
Has thanked: 0
Been thanked: 0

Re: Concave questions

Postby sabraxas » Thu Aug 11, 2016 1:47 pm

downunder wrote: Why do you think I did not? Used to own a 1.5cm concave board and hated it. It was that rigid. The more concave built in, the more rigid the board is. No brainer here.

Yes, the more concave, the more rigid in the concave part. But the tips could be very flexible, thats the case of my board.

Anyway, the Mako is rigid. But it has a very smooth riding, and it is kind with ankles and knees.

As i told,
sabraxas wrote: True is that massive concave with proper outline shape
That could be the case of the board you hate. Not properly shaped. Or you are using it for stuff it wasnt designed for.

Makos are one way travel. 90% of the people never came back :-D


Return to “Gear Builders”

Who is online

Users browsing this forum: No registered users and 51 guests