3D printing large surfboard fins

[MrMik]

I think I have improved the support system for the HARFFTUB fin series by a great lot today.
Not printed yet, though. Surprises are possible.
However, the idea is that I have replaced the cylindrical pads under the fin with elliptical pads. They are much thicker in the middle, and gradually loose thickness towards their edges. I hope this will prevent bubbles of PEI sheet forming in the centre of the pads, where the most intense warping forces try to pull the fin off while it is being 3D printed. I hope that this will result in a much better spread of the forces on the PEI surface of the print bed. At the same time, it reduces the footprint on the print bed, so I have more options for where to put the fins for printing. While a fin is being 3D-printed, the area of the print bed that was used for the previous 3D fin print gets time to flatten out out again.
The ugly cubic stabilisers have also been replaced with elliptical stabilisers. I think it takes longer to render, though.

[MrMik]

The photo looks like it’s rough, but the surface is actually very smooth. It nevertheless needs sanding, The ‘seam’ for the external perimeters is appearing as a raised ridge along one side of the leading edge.
This is the first Wanderfalke fin with Eppler 168 foil.
295g including the support system. The version with the concave foil weights about 274g with supports. So there must be around 20ml of concave.
This one will probably be a good candidate for less than 100% infill 3D printing, because it uses so much filament.

[Surffoils]

Great work, you know you’re going to end up starting a fin business ?

[jago25_98]

I just put a longboard box (inappropriately) into a mini simmons just to test fins like this. I can see you’ve gone a long way in testing now, great!
I’m going to print off one and try it at some point. I hope I can keep up with you though as no sooner as I download a design you’re onto the next! Such is the speed of development!

Do you simply test by moving through water and feeling the resistance or are you riding with them? We’re still in summertime flat here

[MrMik]

But I’m not getting anywhere near as much surf time as I would like at the moment. That will hopefully change again.
.
So far, the main difficulties were related to learning 3D printing and OpenScad designing, and trouble-shooting 3d printer problems.
.
I have toyed with the idea to print fins with a handle instead of a fin base, but that’s stupid as I just realised. Thanks for asking, now I have a much better idea:
I might design and 3D print a handle that attaches to the UTFB in a non-destructive way, maybe even long enough so the hand holding the fin does not have to enter the water.
However, I’m not convinced that will be very useful for testing.
.
However…if combined with repeatable water flow conditions, it might be feasible. I have a 2 person Kayak. If I attach an electric motor to it, I could use a lake on calm mornings to test fins in laminar water flow of fairly consistent speed. I would just need a device to measure torque and lift somehow.
.
But the results from ‘organically’ designing the fins by arranging tubercles so that they look right to me have been very promising anyway. I think I’ll stick with that and hand the resulting fins to good surfers for testing. And eventually I hope to get more surf time myself again.

[MrMik]

Third time ‘lucky’.
The new elliptical support pad system worked very well.
It is only one gram lighter than the old system but more effective and gentler on the print bed.

[Monkstar1]

Any idea what tubercles would do to a rail fin, such as fins with 1 flat side and 1 foiled side?

[MrMik]

I don’t know what tubercles would do on a fin with a flat side.
I think fins should not have a flat side in the first place, but I only surf single fin boards since several years now and don’t miss the extra fins one bit.

[MrMik]

The printer is humming along nicely for once, and I’m managing to crank out a 3D fin print per day. But I’m not keeping up with the post-printing work of finishing them nicely.
Anyway, the aim for now is to get a set of fins to a few surfers so their performance can be compared. Once there is more clarity about what amplitude, frequency and number of tubercles works best, I can proceed to improve the construction of the fins with the best shape(s).
For now, printing solidly from transparent PLA for prototyping seems appropriate. Later on, other materials (possibly a mix of materials) can be used to print proven fin shapes lighter and stronger than the PLA solid variants.

[MrMik]

Looks like the UTFB is a bit too ‘Universal’ when I try to incorporate too many features into the same Universal Tough Fin Base.
Although easily converted to a standard screw-and-plate type fintab, the presence of the Ball Spring Plunger (BSP) holes and the extra aft hole for the swivel string make the area around the aft pin too weak.
The photo shows 2 fins that snapped off while wrcsixeight was trying to remove them from the fin box after they had been in for a while. He is repairing them so he can use them again.
.
So I am 3D printing a few fins for wrcsixeight that do not have the swivel hole or the BSP holes, and the front has the cutout for the plate and screw already removed. He will drill holes for the BSPs exactly where he needs them in his finbox.
.
I have some ideas bouncing around for making a better snap-in system to hold the fins firm enough, but release them in an impact. Until that is ready, I’ll 3D print the fins with either snap-in and swivel-rope-hole, OR for screw and plate. It should be a bit stronger that way. Eventually the aft pin is not going to be required.

[jago25_98]

I’ve added a base from another fin here to make a stl. I haven’t tried printing it. Boolean join failed so I just used ‘combine’ in meshmixer

reduce sways bandwidth bill by downloading from here if you can: http://legoshare.net/63X

https://swaylocks7stage.s3.us-east-2.amazonaws.com/s3fs-public/longboard_base_added_HARF_Tub_Fin_E168_143_2017_08_05_v1.1.1.stl_.txt

[charlieukusa]

well done on the fins they are looking great now! I finally got my prusa mk2s and its been working hard ever since. I have yet to play with finfoil and figure how to add the bases and mounting tabs ect but will have to try to.

I have been playing on fusion360 though trying to draw and print hydrofoil wings, annoyingly its my cad skill that’s holding me back the most with the lofting which is were I should probably see if I can do it in fin foil perhaps. I’m really struggling getting the wing tips drawn properly.

[MrMik]

Thanks, jago25_98 !
I think the fin base you used would possibly be much weaker than the UTFB I am using, at least when I disable the BSP holes.
Triangular holes, or any shapes not very rounded, tend to concentrate stress forces in the corners and break much sooner (or lift off the print bed, or warp, or split etc).
Round or at least oval holes in the base would probably be the strongest, or no holes at all.

[MrMik]

Hi charlieukusa,
how long did you have to wait for the printer? Did you build it from a kit or buy assembled?
The foils you are making are an order of magnitude more difficult than anything I have tried yet.
I don’t think finFoil would work, at least no by itself, because you bend the foils in yet another plane.
However, you could probably create a file in finFoil (and you will be blown away by how easy it is!) and then warp the file by using some other software to act upon it.
These foils will be difficult to print, too. Not even carbon rod insertion is an option due to the foil being curved in at least 2 perpendicular axes.
You are certainly taking on a challenge there!
Are you ‘manually’ designing the internal structures? I would consider just designing the outer layer for a start, and then let the Slic3r fill it. Once you succeed printing the correct outer shape (without the required mechanical strength), you can then add structural strength on the inside with a variety of techniques.

[charlieukusa]

It was supposed to be a 7 week wait it took 11 week. I built it from a kit which took maybe 10 hours taking my time and not rushing, it printed perfect first go.

Yes I thought the curve would be the problem on finfoil, I wonder if that could be added in to the program.

I designed it on fusion 360 importing the airfoil and then doing a plan of the outline, then a section of the anhedrel to which I created the 3d outline.
I then lofted the airfoil to the outline however it doesn’t like coming to a point so had issues there. the internal structure was just added to the airfoil and lofted with it so it tapers down with it which is maybe not perfect.

My plan is just to print a core and then vacuum bag glass and carbon over the top, the test I did pictured is super solid and the thickness could be reduced a lot, it was 2mm I think 1 would be plenty. This would help with print time too I think I did it in 3 sections and two of them together was something like 26hours print time.

like you say joining rod would not be easy however I think if small enough they would work 3 mm should be fine.

what would be realy nice is if the printer was just a little larger and I could print it all in one part

[jago25_98]

I’m using a friends printer to print. I’ll try to print tonight but somehow I expect something will fail on it…

Yes, triangles look better. Would you like to share a STL of the base and the fin? That way we can be testing the same thing and get better test info

[MrMik]

The quiver of easily swappable 3D printed fins is growing.
@ jago25_98 : There are many links in the first post in this thread, including some fin files, STL files .and scad files.

[MrMik]

This is the 20 tubercle version of the HARFin.
.
I’m working on a system that retains, but releases the UTFB from the fin box in an impact. It also closes the empty parts of the fin box.

[MrMik]

The fin retaining system uses 3 different 3D printed parts, and the same ball-spring-plungers as used for the UTFB, and some stainless steel grub screws. They are longer but otherwise similar to the FCS grub screws and the FCS keys can be used to install or adjust the system.

[MrMik]

Another HARF-9_TUB fin is now in possession of an Aussi surfer for testing. I think he’s in for a treat, because so far all surf reports / experiences with these fins have been positive, to say the least.
.
The rest of this post is going to be a pain to read, but it’s not intended for swaylockians, but rather for search bots. The intention is to keep my invention freely available to everyone, by making it reasonably discoverable as existing prior art for surfboard safety fin releases.
Anyone searching for patent surfboard fin safety release system, or Safety surfboard fin release system patent, or patent surf board fin safety system or such key words should hopefully find this post.
.

I’m working on a summary of the ‘Universal Tough Fin Base’ concept, to make it easy to find for any patent lawyers who might be employed to patent anything like it. That might prevent disappointment for future patent seekers for safety fin release patents, because they will not spend much money on a patent, only to find that it will be unenforceable because of ample evidence of ‘Prior art’ having existed before the patent would have been granted.
.
To get started, and not let ‘perfect’ be the enemy of ‘good’, here is a brief summary:

The Universal Tough Fin Base (UTFB) is designed to allow release of the fin from the fin box in an impact scenario when hit from fore or aft, unlike other designs currently in common use. The commonly used designs today either have a roll pin , or a screw and plate on one or both ends of the fin base, and will only release if something breaks. That means either the fin tab snaps off, or the screw, or the box breaks, or the box gets ripped out of the board in an impact. The injury risk to the surfer and other people in the water is high because the force required to break these parts is high. There are a few exceptions, where especially thin screws or other release mechanisms are used for fixing the fin tab at the forward end (in direction of travel while surfing), but none of them allow release when the fin is hit from aft.
.
The adjustable safety fin release mechanism can be easily retro-fitted to existing fin boxes.
.
In addition to allowing adjustable release of the fin from the fin box in impact situations, the safety fin release mechanism also serves to close the part of the fin box that is usually left open (because the fin tab is shorter than the fin box) . The adjustable release mechanism is integrated into parts af variable length, so that the fin can be mounted in multiple position in the fin box, but the unused part of the fin box is filled. This blends the fin box into the general curve of the boards bottom contour and should therefore reduce any unintended impact on the performance of the board.
.
In addition to the ability to release the fin from the box when an impact occurs from fore or aft, I have also developed a system that allows adjustment of the force required before the fin is released. Just like releases on skis, the ‘stiffness’ of the release can be changed according to circumstances and skill of the surfer/skier. With a stiffer release setting, the fin will need a harder impact before it releases from the fin box. Increasing the stiffness of the release system increases the risk of injury to self and others, but reduces the risk of loosing a fin due to an unnecessary release of the fin.
.
Examples:

1. If you are an expert surfer who surfs with one or two Great Whites as company, and no other surfers far and wide, in an area with huge kelp forests, then you might want to use the hardest settings, so that the fin will plough through the kelp or sea grass and only release during a severe impact that would otherwise tear out the fin box.
2. You are teaching you kids surfing, and there are hundreds of other kids and SUPs and surf boats and jet skis etc etc around. You choose the softest setting so the fin causes the least damage whenever it hits something, or your kids fall onto it, from fore or aft.
   .
   The fore and aft ends of the UTFB with adjustable safety release are independently adjustable, so the surfer can set the required trigger force for impact from fore or aft independently. You could set the fore impact release force to maximum, while allowing a light tap from aft to release the fin from the box. Once the preferred location for the fin in the box is known and the system is adjusted accordingly, the fin can then be removed and installed instantly without use of tools.
   .
   Commonly available tools like a 2.5mm Allan key is all that is required to adjust the fin position in the box.
   .
   The trigger force required to release the fin from the box can be changed between several settings, by changing the position or rotation of the parts used. Additional parts, with different properties due to use of stiffer or softer materials, could be used if further variability in release tripper force is required. A continuously variable adjustment of the trigger force for the safety fin release , without need to change parts, to achieve extremely high or low release trigger forces, would be where some innovation could be useful.
   .
   This technology should be freely available for use and for further improvement by anyone who wants to integrate it into their water sport equipment, as well as to anyone who wants to sell water sport equipment, without impediment by patents.
   .
   Milestones in the Fin Safety Release System with adjustable trigger force to document the progress of the invention:
   .
   First conception of Safety Release Fin Base and plan for prototype construction of Dummy Fin Base (DFB) 2016-7-12: http://www.swaylocks.com/comment/526145#comment-526145
   .

DFB drawing 2016-07-13: http://www.swaylocks.com/comment/526163#comment-526163
.
First Dummy Fin Base prototype pattern built 16-7-2016: http://www.swaylocks.com/comment/526332#comment-526332
.
First cast of DFB: http://www.swaylocks.com/comment/526706#comment-526706
.
First test of safety fin release system in surf, ironically including a fin chop injury: http://www.swaylocks.com/comment/526704#comment-526704
.
First Dummy Fin on DFB: http://www.swaylocks.com/comment/526786#comment-526786
.
The growing Dummy FIn Base Collection: http://www.swaylocks.com/comment/527793#comment-527793
.
Renamed to “Tough Fin Base’ TFB’ and first 'TFB” made 2016-09-11: http://www.swaylocks.com/comment/528318#comment-528318
.
DFB + TFB overlay 2016-09-14: http://www.swaylocks.com/comment/528469#comment-528469
.
First use of ‘UTFB’ = Universal Tough Fin Base term (2016-11-14) to describe the evolving concept of the safety fin release system, and the start of 3D printing to make it happen: http://www.swaylocks.com/comment/529299#comment-529299
.
First 3D-printed fin with safety fin release system UTFB on 2017-04-08: http://www.swaylocks.com/comment/536017#comment-536017
.
Early stage of designing swivel-string attachment for safety fin release system: http://www.swaylocks.com/comment/536021#comment-536021
.
First swivel-string design prototype for safety fin release system: http://www.swaylocks.com/comment/536065#comment-536065
.
Destructive testing of safety fin release system 2017-04-09: http://www.swaylocks.com/comment/536066#comment-536066
.
Test surf of safety fin release system at Burleigh Heads 2017-04-10: http://www.swaylocks.com/comment/536124#comment-536124
.
Test surf of safety fin release system without ball spring plungers at Burleigh Heads 2017-04-24: http://www.swaylocks.com/comment/536796#comment-536796
.
Swivel string system for safety release fin improved 2017-04-30: http://www.swaylocks.com/comment/536968#comment-536968
.
Improvement to ‘Internal Stabilisers’ to allow printing of hollow fin shells 2017-05-01: http://www.swaylocks.com/comment/536982#comment-536982
.
Test surf of safety fin release fin 3D printed with 5% infill 2017-05-08 : http://www.swaylocks.com/comment/537235#comment-537235
.
Test surf at Kirra with safety release fat surfboard fin 40mm wide(fin lost and found due to floating) on 2017-05-12 : http://www.swaylocks.com/comment/537363#comment-537363
.
Fins safety release mechanism UTFB printed directly into a fin on 2017-07-14: http://www.swaylocks.com/comment/539390#comment-539390
.
Fins sent to surffoils for testing 2017-07-24 : http://www.swaylocks.com/comment/539463#comment-539463
.
Solidifying micro-cylinders explained 2017-07-28; to make only the safety fin release mechanism / UTFB of the 3D print solid, while using variable infill for other parts: http://www.swaylocks.com/comment/539623#comment-539623
.
Summary of ‘Gow to 3D print a fin’ with safety release system: http://www.swaylocks.com/comment/539652#comment-539652
.

That will have to do for now. More will follow to summarise the documentation up to the ‘state of the art’ for safety release mechanisms for surfboard and other water-rcraft fins. However, it should be clear by now that the development process for the safety release universal fin base has been documented quite comprehensively, and that any attempts to patent it will not be easy to enforce. After all, as far as I know, Swaylocks is the leading surfboard design forum on planet Earth at the time of writing. This is where " Prior Art", or rather 'Current Art" is being defined on an hourly basis.
.

https://swaylocks7stage.s3.us-east-2.amazonaws.com/s3fs-public/TFB+DFB_DSC_0040_crop_overlay.JPG