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FangyFin DIY help, hints and show us ya fin page

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Created by fangman > 9 months ago, 29 Oct 2017
Swindy
WA, 266 posts
23 May 2018 2:30PM
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sailquik said..
That looks like my kinda fin. Plenty of size for me.

If you get time off testing on Workers Comp Swindy, I would be happy to continue the testing at LG for you until you are good again.

I'm sure that can be arranged once the guys here have had a go. It may be a little shorter by the time you get it as the tip is quite thin and our crash test dummy's aren't that careful.

fangman
WA, 843 posts
23 May 2018 2:30PM
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Swindy said...
It depends if you have the work ethic of a student I suppose.


Swindy
WA, 266 posts
23 May 2018 3:04PM
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My Swoody 20 & 17 side by side for comparison. Just a final sand and coat of paint and its done. Any low points will have to wait till next week to get filled, running out of time.
I didn't weigh it before I started but the other 20 started out at 740g and end up 540g. The 17 is now 510g even with 40 g of resin used for the fin box, so was it worth putting in the wood? I don't know but I weighed the off cuts from the cut out and minus the swarf and grinding dust weighed 120g. All the other cutting and grinding I done probably took off another 140g.
No way is this a commercially viable process but if it gives me more options that work well, to me its well worth the effort.



powersloshin
NSW, 1005 posts
25 May 2018 6:41AM
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It looks awesome. Would be good to see a picture from the front to compare the thickness. I was thinking of a 17 a bit like the 20 with the tip cut out and the body made thinner for speed. That would be a lot less work and if there were marks or instructions it could be done more easily by the average person. The main problem I see is how to maintain a good profile when grinding.

Swindy
WA, 266 posts
25 May 2018 6:48AM
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powersloshin said..
It looks awesome. Would be good to see a picture from the front to compare the thickness. I was thinking of a 17 a bit like the 20 with the tip cut out and the body made thinner for speed. That would be a lot less work and if there were marks or instructions it could be done more easily by the average person. The main problem I see is how to maintain a good profile when grinding.

The limiting factor on taking the thickness down more than I have is that this is a hollow fin and if you take off too much there isn't much ally left either side in the hollow area. Its widest point was 22mm and ended up 18.5. The core box had been put in 1mm off centre when cast so 1 side was 2mm thicker than the other. If you got Ross to do a solid casting you could take off as much as you like. The only question is how far can you go before it looses its FF awesomeness and becomes just another delta fin. This fin is more a scaled down fin that would probably be close to what an original FF would be if Ross was to sell another child to pay for its development.


As a FF20 has achieved over 39kn I'm sure in the right hands this one will do over 40. Its not always about speed, a FF will put a smile on the dial in conditions where other fins will leave you feeling frustrated.







decrepit
WA, 9114 posts
25 May 2018 10:44AM
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As long as you don't go too far below 8% chord to thickness ratio the FF should still do it's thing.
But with fins, speed isn't just about drag, it's about lift to drag ratio. Going thin doesn't necessarily improve this. If you have to run at an increased angle of attack to get the lift you need, the drag can go up.

fangman
WA, 843 posts
19 Aug 2018 11:21AM
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The first FF22 off the rank is Sue's Budgewoi special. It has been cut down to just under 17 cm. An important thing to remember if you are doing your own prep ( I forgot and I designed it!) is that the box at the front has the outline of a POWERbox. This box design was to try to make it easier and quicker to grind the casting into a powerbox if required.

IMPORTANT - TUTTLEBOX users - To get the bolt holes to line up with the reinforcing, you need to take 1-2 mm off the very front of the box casting. If you are unsure, put the fin in the board and drill a small pilot hole mark into the fin to see if its correctly aligned, BEFORE you do the bolt hole at 5.0mm.





The second photo is a comparison with a FF20. Sue's Budgewoi special has more surace area and greater foil thickness than the FF20. It will weigh in at approx 750 grams. I am hoping it will provide enough low speed lateral resistance and upwind lift, while keeping the the benign handling charactersitics. I just need to finish it off and get it over to NSW for testing.






sboardcrazy
NSW, 6527 posts
20 Aug 2018 4:14PM
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fangman said..
The first FF22 off the rank is Sue's Budgewoi special. It has been cut down to just under 17 cm. An important thing to remember if you are doing your own prep ( I forgot and I designed it!) is that the box at the front has the outline of a POWERbox. This box design was to try to make it easier and quicker to grind the casting into a powerbox if required.

IMPORTANT - TUTTLEBOX users - To get the bolt holes to line up with the reinforcing, you need to take 1-2 mm off the very front of the box casting. If you are unsure, put the fin in the board and drill a small pilot hole mark into the fin to see if its correctly aligned, BEFORE you do the bolt hole at 5.0mm.





The second photo is a comparison with a FF20. Sue's Budgewoi special has more surace area and greater foil thickness than the FF20. It will weigh in at approx 750 grams. I am hoping it will provide enough low speed lateral resistance and upwind lift, while keeping the the benign handling charactersitics. I just need to finish it off and get it over to NSW for testing.








With the level back to < 0.30 I will need that..

tbwonder
NSW, 175 posts
4 Sep 2018 2:21PM
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My Fangy 18 arrived yesterday. From here on to be known as the FF167. The actually fin length is 167mm
I've spent about 2 hours on it and it is starting to look half reasonable

In the hand and next to other fins it is comically small, but installed in the 44cm board it looks rather pleasing.
Just need a nice 35 knotter to test it out





fangman
WA, 843 posts
4 Sep 2018 9:20PM
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Looks damn good! But that must be a tiny board, or there is some Hollywood trickery with the camera, because the fin actually looks big enough to be useable Bring on a howling breeze, I am super keen to see what happens

tbwonder
NSW, 175 posts
5 Sep 2018 12:08PM
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No trickery was intended, the board is 26cm wide just in front of the fin.

fangman
WA, 843 posts
5 Sep 2018 7:50PM
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tbwonder said..
...the board is 26cm wide just in front of the fin.


I have toothpicks wider than that!!

sboardcrazy
NSW, 6527 posts
12 Sep 2018 11:42AM
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tbwonder said..
No trickery was intended, the board is 26cm wide just in front of the fin.


Now you just need wind..

morts
WA, 133 posts
2 Nov 2018 8:31AM
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What are people using to fill & cap the void? I was considering using expanding foam but thinking I may end up with an eruption of foam everywhere. Just normal silastic to cap or a particular type?

fangman
WA, 843 posts
2 Nov 2018 9:41AM
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morts said..

What are people using to fill & cap the void? I was considering using expanding foam but thinking I may end up with an eruption of foam everywhere. Just normal silastic to cap or a particular type?



Morts I have been using a wedge of polystyrene packing foam, jammed in to make a plug and then a thin layer of Silastic (Selleys Bathroom version, but I dont think this is critical) over the top to seal it. So far, it's been fine.

morts
WA, 133 posts
2 Nov 2018 1:35PM
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Thanks Fangy

sputnik
SA, 24 posts
23 Jan 2019 10:04PM
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Here it is Ross
1000 grit finish, good enough?

fangman
WA, 843 posts
23 Jan 2019 9:19PM
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sputnik said..



Here it is Ross
1000 grit finish, good enough?


Compared to Tricky's that is the Crown Jewels :-) Looks very nice Jeff - damn good job! Now use any means possible to nobble Tricky in any 'head to head' contests in future.
Good grass too!

Swindy
WA, 266 posts
22 Apr 2019 6:00PM
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I have just finished a little R&D project for fangy. I was given the task of taking one of his original solid 24 fins and making a speed version. So out came the grinder and hacked into it making it about 5mm thinner just above the fillet and tapering it down all the way to the tip while trying to keep a decent foil shape equal on both sides. Then undone most of my hard work by cutting out the centre of the fin for the balsa wood insert. Having done this a few times now it doesnt seem to get any easier or quicker. Shaping the balsa back to the foil shape is probably the quickest operation. Then 3 layers of glass each side, sand, bog and sand again. Then a coat or 2 of spray putty and a wet n dry. Its now ready for TheFangman to add his finishing touches to it, as he did with the previous project i done for him. (Butcher)








Hopefully we get some wind soon to get some feedback on how it works.

decrepit
WA, 9114 posts
22 Apr 2019 6:08PM
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Nice job Roger.

fangman
WA, 843 posts
23 Apr 2019 3:46PM
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Looking good Roger. The very skinny FF 22mod I did is slippery and fast but quite unpredictable on the small downhill chop once I get past 32 knots. More experimenting to be done...I am really looking forward to seeing how your modified FF24 behaves...and then butchering it
BTW my other Swoody is still perfecto, with no sign of fibreglass separation from the aluminium.

Swindy
WA, 266 posts
23 Apr 2019 4:57PM
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Wish the same could be said of my 22 swoody. Twice now one side has completely ripped off. I put it down to the glass sold in bunnings doesnt soak up the resin properly. I think the ones holding together well are from when i had some decent glass. Dont worry i got some more decent glass for yours and to re do my 22. It also lifted on the 17 swoody so Mike re done it as its in his fin collection.

olskool
QLD, 1283 posts
23 Apr 2019 7:51PM
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Swindy, maybe use coarser sandpaper before you glass? Itll leave a rougher surface for the resin to key onto n grip.
Worth a try.

Swindy
WA, 266 posts
23 Apr 2019 6:33PM
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olskool said..
Swindy, maybe use coarser sandpaper before you glass? Itll leave a rougher surface for the resin to key onto n grip.
Worth a try.


I use 80 grit, that should be ok. The problem is even though i soak the glass with resin and roll the living daylights out of it when you sand down the excess it goes fluffy. The ones i have done with glass from west systems haven't been a problem either sanding or coming appart.

olskool
QLD, 1283 posts
23 Apr 2019 8:51PM
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^^ Ahh, any brandname linked to the glass matting? So it fluffs up like sanded Kevlar??

decrepit
WA, 9114 posts
23 Apr 2019 7:07PM
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trouble is, rollers don't work so well with resin on top of the cloth, they are much better with resin under the cloth. Squeegees work better with resin on top, you can force the resin down, rollers force the resin up.

I had some carbon that just wouldn't wet out, no matter what you did. I was told it was meant for resin infusion systems, may be there's glass in that category as well.

jirvin4505
QLD, 1010 posts
23 Apr 2019 9:25PM
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Yes better quality glass is good. Plus Re roughen the aluminium with fresh epoxy on sandpaper just before adding glass. It improves the bond. Think this is mentioned somewhere in the west system manuals

cheers Jeff

Swindy
WA, 266 posts
23 Apr 2019 7:57PM
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jirvin4505 said..
Yes better quality glass is good. Plus Re roughen the aluminium with fresh epoxy on sandpaper just before adding glass. It improves the bond. Think this is mentioned somewhere in the west system manuals

cheers Jeff


Good tip jirvin, i will try that next time.

Swindy
WA, 266 posts
23 Apr 2019 8:01PM
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decrepit said..
trouble is, rollers don't work so well with resin on top of the cloth, they are much better with resin under the cloth. Squeegees work better with resin on top, you can force the resin down, rollers force the resin up.

I had some carbon that just wouldn't wet out, no matter what you did. I was told it was meant for resin infusion systems, may be there's glass in that category as well.


I put resin on liberally first then lay the glass on and roll it with a metal roller till it soaks through, add some more resin and repeat for 3 layers.

Swindy
WA, 266 posts
23 Apr 2019 8:09PM
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olskool said..
^^ Ahh, any brandname linked to the glass matting? So it fluffs up like sanded Kevlar??

Cant remember brand name but assume bunnings only sell one brand nationwide.
I havent sanded kevlar as yet but its obvious the resin hasnt soaked completely into the glass. Once sanded i give it a brush coat of resin then sand it again but still dont get a 100% satisfactory finish.
No issues with the new glass though.



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"FangyFin DIY help, hints and show us ya fin page" started by fangman