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3D Printing Fins
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dllee



Joined: 03 Jul 2009
Posts: 3975
Location: East Bay

PostPosted: Fri Aug 01, 2014 11:33 am    Post subject: Reply with quote

Nice template, and harder to tell, exact foil.
Most CAD designed fins need quite a bit of human hand work to finish, so companies are wondering how to cut out the human part, which totally determines how good the fin actually performs on the water.
Even the best of fins, the human part can make the fin fast, OK, or barely passable, or a spin out monster....
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rigitrite



Joined: 19 Sep 2007
Posts: 463
Location: Kansas City

PostPosted: Fri Aug 01, 2014 2:19 pm    Post subject: Reply with quote

I agree that a printed fin would probably fail. The types of plastics available to be printed cheaply and easily, universally lack the kind of strength a fin would require to resist all those bending forces.

However, I donít believe that youíre exploiting the primary advantage of 3-d printing: complex shapes and cavities! You could easily and simply weld up a reinforcing structure out of standard sized mild steel strap or T-bar. Then, model a structure within the fin to hold it. Print the fin in two halves, insert the steel innards, and bond it together with epoxy when done. The plastic surface would provide the hydrodynamic qualities you want, while the steel would resist the large forces. You could even print most of the fin as hollow (with a honey comb structure) to reduce weight. The metal would be encased in water-tight plastic, so corrosion would not be an issue. This is an intriguing idea.

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doremmg



Joined: 07 Jul 2004
Posts: 7

PostPosted: Fri Aug 01, 2014 4:15 pm    Post subject: Reply with quote

well I guess we are all wrong. I just took the fin out for a spin in 18kt winds on a 110L and 6.5m2 and it worked great! I only sailed for about 20 minutes and was babying it a little bit but I was fully plaining, hooked in and in the straps. No problems at all.

The next test will be to take it offshore a bit, I am going to have a chase boat do the filming (and rescue if needed)



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doremmg



Joined: 07 Jul 2004
Posts: 7

PostPosted: Fri Aug 01, 2014 4:16 pm    Post subject: Reply with quote

rigitrite wrote:
However, I donít believe that youíre exploiting the primary advantage of 3-d printing: complex shapes and cavities! You could easily and simply weld up a reinforcing structure out of standard sized mild steel strap or T-bar. Then, model a structure within the fin to hold it. Print the fin in two halves, insert the steel innards, and bond it together with epoxy when done. The plastic surface would provide the hydrodynamic qualities you want, while the steel would resist the large forces. You could even print most of the fin as hollow (with a honey comb structure) to reduce weight. The metal would be encased in water-tight plastic, so corrosion would not be an issue. This is an intriguing idea.


I thought about that but my idea was to make this as simple as possible. This is only the first revision so if this fails I can try something like you mentioned.
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rigitrite



Joined: 19 Sep 2007
Posts: 463
Location: Kansas City

PostPosted: Fri Aug 01, 2014 4:34 pm    Post subject: Reply with quote

cool

I hope it holds up. All the fins I ever made by hand worked great.....until they snapped off at the base. This usually happened after about 10 sessions.

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swchandler



Joined: 08 Nov 1993
Posts: 9153

PostPosted: Sat Aug 02, 2014 3:09 am    Post subject: Reply with quote

You might want to put a smaller fin in that backpack you've got. That way if the fin snaps off at the base, you've got a spare fin to slog in on. Better to be prepared for the worst case scenario. Also, at intervals, you might want to check the fin at the base for indications of stress.
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Waterat Pat



Joined: 10 Apr 2000
Posts: 169

PostPosted: Sun Aug 03, 2014 8:17 am    Post subject: Reply with quote

Well done! I am curious about your materials I know 3D printers use HDPE but it looks like you glassed over that with resin and glass. Normally the two don't stick well to each other. Most plastic fin manufacturers use a composite plastic with fibers or other fillers added to stiffen up the fin. Can you use different plastic compositions in your printer?
Once again well done.
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xander.arch



Joined: 23 Apr 2009
Posts: 217

PostPosted: Sun Aug 03, 2014 1:07 pm    Post subject: Reply with quote

Cool project. I'm curious to know what program you used to model the fin and how you developed the profiles?
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isobars



Joined: 12 Dec 1999
Posts: 18712

PostPosted: Sun Aug 03, 2014 1:24 pm    Post subject: Reply with quote

doremmg wrote:
my idea was to make this as simple as possible.

We timid souls who think boards and fins are made on Mars by elves rolled our eyes at that observation. To us, "simple" means buying such stuff off a shelf at a shop or swap meet. Just skimming this thread took me longer than acquiring a new fin does.

I never know whether to bow in awe or shake my head in bewilderment at the lengths some gifted -- or is it crazed -- people go to re-invent wheels. I'm a very accomplished fabricator in some media, but I don't bother unless I have no other choice. You guys are either nuts or gods, and as such I'm not sure whether you deserve sympathy or reverence. Very Happy
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Ugly_Bird



Joined: 04 Nov 2008
Posts: 228

PostPosted: Sun Aug 03, 2014 2:29 pm    Post subject: Re: fin printed Reply with quote

edoremus337 wrote:

It flexes way more than a G10 fin so I imagine it will fail pretty quickly..


Congrats! I always admire someones persistence on projects like that, especially when most people around say that it is not going to work well. It's fun to listen to them after the thing works Smile

Keep pushing!

I was thinking how it would be possible to strengthen a 3D printed fin. After printing it inherently has porous structure and I see that you already use some sealant. SO, using some very thin sealant for the first path to penetrate deeper and the second to smooth the surface could be a good approach. I used some structural sealant to repair old failing wood with a lot of cracks. It was turning wood into a bone. Unfortunately I do not remember what I used. Sure that 3M has something suitable.

Also, these fins could be good for beginners who are more prone to damaging/scratching fins.

Good luck!

Andrei.
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