Recent topics
Which table to choose
Kite setup tips/tricks
Which Front Pad
Futures Fins Alpha Fin Release
Kitesurf / Surfboard
Strapless Air Transition with heli-loop
Movie: White Caps and Summer Hacks
Lake Erie Wave Day
Global announcments
SHAPE - what makes a fast kite surf board
Make your own fins - #2 THE FIN SHAPER
Make your own fins - #1 THE COPYCAT
Build - Full wood UG Kipuna style board
Video - Jon Modica Latest Footy
Video - Trip - SDC
Video - Reo and Modi in Maui
Video - invisable - SDC
Recent posts
Re: A Work In Progress: Video by Nate Apple
Re: Movie: White Caps and Summer Hacks
Re: Which Front Pad
Re: Lake Erie Wave Day
Re: LF Skate 5'11" 2008 vs LF Skate 5'11" 2009
Re: Kite setup tips/tricks
Re: Which table to choose
Re: Strapless Air Transition with heli-loop

Make your own fins - #1 THE COPYCAT

Welcome to losethestraps.com - the original site dedicated to kitesurfers that are evolving the strapless scene. Please introduce yourself to the forum by posting here.

Moderator: Lonny

Make your own fins - #1 THE COPYCAT

Postby tungsten » Tue Oct 30, 2012 7:41 am

Why would anybody in his right mind make his own fins?


Because he can 8)


So you decided you want to make your own fins. You've got this brilliant set of fins, and you want a copy - they are hard to get by, you might lose yours, because you need them on another board, or you start using boards with a different box system your fav fins are not made for. Many good reasons.


Get started with making a mold - side fins

There is a bazillion ways to make molds. Any of the methods (molding silicone, plaster, plastilin, deep drawing ...) have their advantages and disadvantages: price, availability of the material, rigidity of the mold, heat resistance, necessary machinery ... I tried some and ended up with a method called "deep drawing", which consists in thermo forming a plastic sheet around the sample in order to get a negative mold. There are lots of useful youtube clips about it, so I won't explain every little detail. Here we go.


1. Start with building a vacuum box. It's a closed air tight box with lots of holes on the top and a big hole in front. This is for the hose of the shop vacuum cleaner.


DSC08693a.jpg
DSC08693a.jpg (41.44 KiB) Viewed 1052776 times



2. Beautiful box. Now we need the material our mold is going to be made of. I found sheets of clear 0,7mm PET in a hardware store for cheap, 5€ per m2. PET is a kind of polyester. This is the stuff coke bottles are made of, although coke bottles are thinner. PET is easy to work with and if you fark one sheet up, it won't blow your budget.

There are other materials like PP, PE used for deep drawing. You can try those as well if you get sheets of 0,7mm to 1mm thick.

A pic of the trimmed PET sheets I use:


DSC08691a.jpg
DSC08691a.jpg (29.47 KiB) Viewed 1052776 times


3. Prepare the box and sample. I stick a rubber lip (window insulation) on top of the box so that the PET sheet will sit air tight on top of it. The sample (your fin) fits nicely in the free space. Close all the holes around the rubber lip with tape. Only the holes inside the rubber lip are open.


4. Form the mold
-Heat up the sample fin in boiling water. This is important. Otherwise the PET sheet will cool out once it touches the fin.
-Now place the fin on the vac box, and place one sheet of 0,7mm PET on top.
-Heat the PET sheet a couple minutes with a hair dryer until it gets soft.
-Activate the shop vac (or any household vacuum cleaner for that matter). The vacuum will suck the sheet down on the sample fin. Keep heating the sheet until it lays smug and snug on the fin. Pay attention to edges and corners.
-When you're happy with the result, keep the vac running for another minute cooling down the sheet with cold air (if you hairdryer doesn't do cold air, use a wet rag or think of something else).

DSC08694a.jpg
DSC08694a.jpg (41.35 KiB) Viewed 1052776 times



This is the result: a nice negative form of your fin.


DSC08688.jpg
DSC08688.jpg (40.34 KiB) Viewed 1052776 times



5. Cast your fins
-Wax down your mold with car wax or a proper release agent
-fix it to some wooden frame. Why use a frame? Epoxy gets hot when curing. You want something stable around the mold when it comes to casting.
-fill the mold with fibreglass left overs. Make sure there are lots of layers on the top part where the fin connects with the fin box. This is critical. -Alternatively, you make an insert out of G10 and put in the mold in the right place before pouring the resin. That's what I did. Inserts:


DSC08686a.jpg
DSC08686a.jpg (43.46 KiB) Viewed 1052776 times



-Pour the resin. Some practical tips:
-use universal tints for poured epoxy. They contain emulsifier, which guarantees the epoxy to mix well; also looks better.
-don't cast more than 7-8mm thick layers at a time; epoxy will become too hot and form bubbles. If your fin is thicker, pour a first layer, wait until it gels (half an hour or so, depending on temperature), and pour a second layer.


DSC08317.jpg
DSC08317.jpg (52.28 KiB) Viewed 1052776 times



DSC08319.jpg
DSC08319.jpg (40.79 KiB) Viewed 1052776 times



After the epoxy is cured, I put the mold as is in the oven at 50ºC for 20 minutes. Take out of the oven and cool rapidly (cold water or fridge). This helps disconnect the new fin from the mold


Take out your new fin and finish it (cutting of leftovers, sanding). When it's ready, you will want to harden it. Put the fin in boiling water for 30 minutes. Why? Epoxy cures under heat. THe complete curing process take 1 week. The hotter, the better (up to 100ºC that is).

Another thing: When epoxy is hot (over 80ºC, called the glass point), it gets soft and you can form it, bend it, whatever you want. It stays in that position after cooling down. So if you want to build a cant into your fin, just heat it up after making it, bend it, cool with cold water for a minute, and you're set.


And this is the result (before sanding and finishing). Those copies are true to the original to 1/10 of a millimeter. That is quite acceptable.


DSC08685.jpg
DSC08685.jpg (149.85 KiB) Viewed 1052775 times



Good tinkering!

cheers, tungsten
Last edited by tungsten on Wed Oct 31, 2012 6:14 am, edited 6 times in total.
tungsten
Shredder
 
Posts: 243
Joined: Wed Mar 11, 2009 4:24 am
Location: Malaga, Tarifa, Spain
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby tungsten » Tue Oct 30, 2012 8:39 am

Make a mold - center fin, which is symmetric

In order to make the molds for the center fin, you need a support to carry your fin, covering exacly half of it. I cut and sanded my support out of 5mm ply. It works both ways (for both sides of the fin). This is what it looks like:

DSC08697.jpg
DSC08697.jpg (26.39 KiB) Viewed 1052775 times



Place the fin on top, place the whole on top of the vacuum box, and make your two halves of the mold.


DSC08698.jpg
DSC08698.jpg (21.83 KiB) Viewed 1052775 times



Now you're ready to cast your fin.
-drill a hole for a straw like in the picture
-fill the two halves with pieces of fibre glass - in the pic there's no glass inside the mold, it's just for the photo.
-put the insert in its place
-stick tape around he border of the two halves. Otherwise the resin will drop out
-clamp halves together. More clamps than in the pic
-put the mold in a position so that the straw hole is at the highest point. NOT LIKE ON THIS FOTO
-insert resin with a syringe through the straw. it's important to fill the mold slowly from bottom to top. Otherwise air can't escape.


DSC08702.jpg
DSC08702.jpg (43.83 KiB) Viewed 1052775 times



That's roughly it. You'll have to play around in order to get good results. As I said: who's stupid enough to make their own fins?


cheers, tungsten
tungsten
Shredder
 
Posts: 243
Joined: Wed Mar 11, 2009 4:24 am
Location: Malaga, Tarifa, Spain
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby laosmataoan » Mon May 09, 2022 10:26 am

Wow! I can't imagine that this is possible. I should keep this for future reference if I have time to do it by myself. This is really amazing! Thanks for sharinghttps://www.getrecommended.com/leanderhandyman/
laosmataoan
Getting Wet
 
Posts: 15
Joined: Wed May 04, 2022 9:32 pm
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby SofiaL » Mon May 09, 2022 9:41 pm

This is really nice idea. wanna try this one!drywall contractor chicago ilThanks. San Antonio Texas Sump Pump Installation
Last edited by SofiaL on Thu Jul 07, 2022 5:45 am, edited 1 time in total.
SofiaL
Getting Wet
 
Posts: 21
Joined: Thu Apr 07, 2022 5:34 am
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby Annasmith » Fri Jun 10, 2022 11:04 pm

I really admire you. I want to make it just like yours. crawl spaces St Louis, MO pizza
Last edited by Annasmith on Sat Oct 08, 2022 9:41 am, edited 1 time in total.
Annasmith
Getting Wet
 
Posts: 13
Joined: Fri Jun 10, 2022 10:57 pm
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby valsoansalosn » Mon Jun 13, 2022 11:32 pm

I am also thinking of making my own fins and this step-by-step process could be a great help as a beginnermobilefoundationrepair.net
valsoansalosn
Getting Wet
 
Posts: 19
Joined: Wed May 11, 2022 10:34 am
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby monimorklea » Sat Jan 28, 2023 10:47 pm

Although coke bottles are thinner, this is the material used to make them. PET is simple to deal with, and if you mess up one sheet, your budget won't be blown. book now
monimorklea
Getting Wet
 
Posts: 26
Joined: Tue May 17, 2022 7:03 am
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby katherinebridge » Fri Jun 09, 2023 4:30 am

You make an insert out of G10 and put in the mold in the right place before pouring the resin. That's what I did. commercial demolition wellington
katherinebridge
Grom
 
Posts: 5
Joined: Mon Sep 12, 2022 10:41 am
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby Faith Sarim » Sun Jun 18, 2023 11:19 am

So if you want to build a cant into your fin, just heat it up after making it,photo booth rental bend it, cool with cold water for a minute, and you're set.
Faith Sarim
Getting Wet
 
Posts: 22
Joined: Thu Apr 07, 2022 5:32 am
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby valsoansalosn » Tue Sep 19, 2023 10:32 am

Your favorite fins are no longer appropriate when you start using boards with a new box system. Numerous justifications. lawn mowing wellington
valsoansalosn
Getting Wet
 
Posts: 19
Joined: Wed May 11, 2022 10:34 am
Share |

Re: Make your own fins - #1 THE COPYCAT

Postby monimorklea » Wed Oct 11, 2023 11:24 am

Remove from the oven and quickly cool (in a refrigerator or with ice water). This facilitates separating the fresh fin from the mold. | manufacturing factoring Seattle
monimorklea
Getting Wet
 
Posts: 26
Joined: Tue May 17, 2022 7:03 am
Share |


Return to Welcome

Who is online

Users browsing this forum: No registered users and 3 guests

cron