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Board build question on rails .?

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Created by forceten Two weeks ago, 19 Jun 2020
forceten
1163 posts
Wednesday , 1 Jul 2020 1:16AM
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Looking better. I have boxed the rails, I am going to add core cell to the bottom, then do the rails.
iam working on the thickness,rockers.

Rolling Stones , no not them .

Gestalt
QLD, 12761 posts
Wednesday , 1 Jul 2020 12:49PM
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just a heads up incase you are not aware.

rocker needs to be cut into the blank from templates. if you are trying to hand sand the rocker it probably wont work because of the same problems had with the rails.

the idea is to finish the rocker and bottom contours before gluing the hardcore foam. being hardcore foam it needs to be vacuum bagged too.

if you don't have a vacuum bag i'd avoid the hardcore foam to the bottom and maybe just use it on the deck around the flat areas.

forceten
1163 posts
Wednesday , 1 Jul 2020 8:58PM
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Select to expand quote
Gestalt said..
just a heads up incase you are not aware.

rocker needs to be cut into the blank from templates. if you are trying to hand sand the rocker it probably wont work because of the same problems had with the rails.

the idea is to finish the rocker and bottom contours before gluing the hardcore foam. being hardcore foam it needs to be vacuum bagged too.

if you don't have a vacuum bag i'd avoid the hardcore foam to the bottom and maybe just use it on the deck around the flat areas.


Why won't it work ? The outline was by the Cnc , it just needs thinner. i have a vacuum, it's been used before on my last board.

Imax1
QLD, 2745 posts
Thursday , 2 Jul 2020 6:49AM
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Oh dear.

515
476 posts
Thursday , 2 Jul 2020 5:31AM
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Ok get a rocker jig cut from 25mm MDF.
Suggestion A
You could vacuum the bottom sandwich on and basically over vacuum so the board bends to match the rocker jig.
Suggestion B
Or 1 layer of 4 oz on deck and weight to make the board bend to match jig, do a dry run first to get how many weights you need and where.
Put plastic under your weights and you the glass will wrinkel so squeege those out.
Then vacuum bottom sandwich again using jig.
Good luck

Gestalt
QLD, 12761 posts
Thursday , 2 Jul 2020 8:39AM
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Select to expand quote
forceten said..

Gestalt said..
just a heads up incase you are not aware.

rocker needs to be cut into the blank from templates. if you are trying to hand sand the rocker it probably wont work because of the same problems had with the rails.

the idea is to finish the rocker and bottom contours before gluing the hardcore foam. being hardcore foam it needs to be vacuum bagged too.

if you don't have a vacuum bag i'd avoid the hardcore foam to the bottom and maybe just use it on the deck around the flat areas.



Why won't it work ? The outline was by the Cnc , it just needs thinner. i have a vacuum, it's been used before on my last board.


master shapers use an electric plane to shape the rocker and they constantly overlay a template.
to do it by hand with a sanding block and no template in my mind would be almost impossible to get an accurate outcome.

decrepit
WA, 10023 posts
Thursday , 2 Jul 2020 8:07AM
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Rocker on a windsurfer is critical around the feet area, 1mm can make a big difference. There's a thread here somewhere about negative rocker between the feet, and how much difference it can make to top speed.

I always check rocker between mast and tail at all stages of production. The vacuum bag can add a little or subtract a little even if it's clamped to a jig. It's the difference in compression of the foam. If you're bagging the bottom on, the foam at the deck will compress more. when you release board from jig the rocker will change.

Mark _australia
WA, 19839 posts
Thursday , 2 Jul 2020 8:14AM
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Yup that's why I don't 'shape' rocker too.
The hotwire cuts it and all I add is concave and vee. Majority of the bottom hardly gets touched.
Then a big MDF rocker jig for bagging it. Can't go wrong then. Unless you apply too much vac and crush the blank

I think however that Forceten means just reducing the deck down a bit? CNC bottom would be sooo close there'd not be much to remove, its mostly upper rails that are stepped...?

forceten
1163 posts
Thursday , 2 Jul 2020 9:40PM
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Mark is correct, all questions.
Decrepit, I will have tail rocker, 5-7. I have not heard of this extending forward .

Ir- respective of the nose rocker comments, the shape was cut by the cnc . I trimmed the area .I compare to other boards , and am happy with the measure 185, and the shape, I may need to blend more into the flat.My intend , long ago was a flat bottom, but I feel I can do a small Vee, using a tool I made from imax suggestion.
This area for this is a question I need help with.
Iam working with some specialist tools. . Since my health is poor, it's unlikely I will do another large or any project.
For the board durability , I could not do the core cell, but I have it and materials .
i will in the stress areas insert core cell , mast , boxes .

appreciate the helpful suggestions!

decrepit
WA, 10023 posts
Friday , 3 Jul 2020 8:32AM
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I think you need to be more precise about what you need help with, I've no idea.

Mark _australia
WA, 19839 posts
Friday , 3 Jul 2020 9:22AM
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No corecell (except for inserts) will be fine if its dense enough and maybe wood or lots of carbon in standing area.
What density foam?

185 nose and 5-7 tail would be a good FSW. Give it some vee though.

forceten
1163 posts
Friday , 3 Jul 2020 9:57PM
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Select to expand quote
decrepit said..
I think you need to be more precise about what you need help with, I've no idea.


I think for you the length from tail forward for the nose rocker ?

forceten
1163 posts
Friday , 3 Jul 2020 9:59PM
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Select to expand quote
Mark _australia said..
No corecell (except for inserts) will be fine if its dense enough and maybe wood or lots of carbon in standing area.
What density foam?

185 nose and 5-7 tail would be a good FSW. Give it some vee though.


It's 2lb. I don't remember what that translates to in your measure, but is dense, most are 1 or 1.5 .Yes Vee, now where at ?

decrepit
WA, 10023 posts
Saturday , 4 Jul 2020 8:47AM
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Select to expand quote
forceten said..
It's 2lb. I don't remember what that translates to in your measure, but is dense, most are 1 or 1.5 .Yes Vee, now where at ?


mike@mike-ThinkPad:~$ units 2lb/ft3 kg/m3
* 32.036927
/ 0.03121398
mike@mike-ThinkPad:~$
So 32kg/m>3, that's fairly dense for eps, but too soft for a light glass job. I've never done a board like that, you may get away with a couple of layers of carbon, maybe 3 layers of glass.
I'm not sure on your board, on a wave board I have v all the way, but it becomes spiral from the footstraps to the tail. On a flat water board, I have a 1m flat section under the feet small spiral v behind the feet and hollow v forward.

Gwarn
70 posts
Sunday , 4 Jul 2020 11:03PM
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1.5 and 2 lb Eps foam is what the blank manufacturers offer in the US. Even with deck patches it's to soft under your feet it will crack on a slapper board.

I used 2.0lb on my current foil boards I'II be lucky to get 100 days on this board..

Deck 2 layers 6 oz S glass + 2 patches of 6 oz under deck pad.
Bottom 2 layers 4 oz S glass + 4 patches over the tail for the box.
Plus some vetor carbon netting for looks.
Pro-Set epoxy

This board is already soft on the deck from my feet 20+ days. It was fast and cheap to build that's the plus. If it gets me through the season then my goal was reached. This is a foil board and not a slapper I don't think a slapper will last a whole season with this lay up schedule.

There are more photos in my profile..








forceten
1163 posts
Sunday , 5 Jul 2020 4:31AM
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Nice looking.
no carbon, I would already have prob twice as much glass
planned as you if I don't use core cell.
It's been over 2 years , that I looked at a blank sales, only recall 1.5 max.
this came from a non windsurf company, that had a basic CNC machine, the cost was less than shipping for a blank, and I got 2 full size and 1 prob 85l.
more than one way to bake a cake.
Thanks for the info. cheers

forceten
1163 posts
Sunday , 5 Jul 2020 9:26PM
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I missed the carbon part, 100sessions for me might be 5 + years. At 73yo, I don't need things that will outlive me

forceten
1163 posts
4 hours ago , 7 Jul 2020 7:16AM
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I can fix it



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"Board build question on rails .?" started by forceten