So what material did you settle on for printing? Is it still in PLA?
You can use Polymax PLA for the entire fin. Although, I'm not sure if I have actually tried that.
The colour banding of the fins shown earlier is very intentional. The trailing edge and the screw plate projections must be maximally strong. The middle part, where the carbon bars are, can be printed using a cheaper filament. The first few layers build the sacrificial support system and can be printed from some cheap PLA.
The last colour change at the fore end of the UTFB is not really required, but you need to change filament to cheap before printing the next fin, anyway. And closing the carbon bar shafts fore and at the base with a hand-held 3D print pen will then require the cheap filament in the pen, no changes required.
Below are the manual editing levels required to program the filament changes into the .gcode file
Filament changes x 4 for 0.20mm layers:
Filament 1: esun PLA+
Filament 2: Polymax PLA
z0 to z 7.0 Filament 1 esun PLA+ for base - makes support system and coloured screw plate end without weakening anything and minimises expensive filament use
z7.0 to z 47.0: Filament 2 Polymax PLA - makes structurally important part of screw plate end and the trailing edge from the best available material
z47.0 to z105.0: Filament 1 esun PLA+ - the entire part with vertical carbon bars
z105.0 to z140.0 Filament 2 Polymax PLA - fore screw plate projection between set screw and first carbon bar
z140 to finish Filament 1 esun PLA+ - tip of fore screw plate extension.
Printer settings will have to wait a little, I'm flat out like a lizard drinking at the moment.
Here is a file tha can be used to make the fin by subtractive methods, like CNC milling.
The support system and the hollow shafts are removed.
Let me know if anything eeds to be changed to make it easier to use.
Here is an STL file of the Universal Tough Fin Base (UTFB) by itself.
No carbon bar shafts in this one.
Plonk your own fin creation on it and enjoy!
Another snapped fin, another lesson learned: The carbon bars must be glued or epoxied into the fin, or fin strength will suffer greatly. No fins with bonded bars have snapped yet.
The previous files were named incorrectly. I have renamed and compressed them. I would appreciate if someone could try them out and let me know if there are any issues with them.
Readers should note that this fin snapped after many sessions of trying to break it when turning, short of intentionally driving it into sand/reef.
It snapped kicking out of a wave on my forehand. I had noticed a crack many sessions previously in front of the first turbucle at the base. With horozontal carbon bars supporting the tabs It was obviously not in danger of breaking out of the board, so I left it in place. The session before it snapped I noticed that the flange was no longer resting super tightly on the hull, like when I first fitted it to my stretched fin box. It should have been obvious to me that it was fatigued but I was also told to try and break them.
I believe the flange added some leverage which stretched/fatigued the PLA just below it, until it let go. I feel the flange stretched/ stressed/fatigued the PLA base in a narrower spot than a flangeless fin would. Bonding the bars inside the fin and to each other, will add considerable strength to the fin. I doubt the amount of pulltruded carbon bars inside this fin could be pursuaded to break at the junction under normal surfing loads, I suspect with the pulltruded carbon bars epoxied in place in the fin would break the finbox/board first. Time will tell.
One can see the cloth on the sides of the base of the fin, that which resides inside the fin box that I added to get a super tight fit in my worn/ stretched finbox. I do this to all fins I received adn try, which makes it difficult to hand off for others to try, as the bases then need to be sanded thinner to fit their boards.
The cloth on the sides of the base that I added, might also have concentrated loads just below the flange
I did not lose any of the carbon bars. I felt and heard the fin break and quickly ended the turn and jumped off the board. The fin slid about 4 inches from the hull of the board riding up the carbon bars, I reseated it, flipped the board over fin first, took the next line of whitewater in, and got out.
I really liked this fin. It was one of the best of these gullwhale fins top 4 easily. I'll probably stick it back together someday, epoxying the carbon bars inside. I will be extracting the bars from any fin in which they are not bonded, and epoxying them rather than polyurethane glue, which I am biased against.
These bars were loose in the fin so I could add or subtract bars to dial in a lateral and rotational flex I liked. I never got around to doing that with the same fin. The absolute stiffest GWfin was not my favorite, and too flexy was my least favorite fin by a huge margin, but I could see how someone lighter would enjoy how that super flexy fin would load and unload.
My personal happy middleground in terms of finflex, has yet to be fin(e) tuned.
When this fin was newly fit, it had the best fit in my finbox yet, with No wobble at all at the base, helped by the flange resting on the hull. I'm pretty adamant about this tight fit at the box before attempting to form an opinion of a fin.
Hans found a very interesting page about Tubercled Wing Design.
It explains a lot about why the G-Whale fins act like they do.
The screw-plates are required to use the UTFB.
They can also be used with other fins, they have many advantages over standard screw and plate systems.
I use a 3D-print-pen to lock the nut in place after press-fitting it into the PLA. Some sort of glue should also work.
The position of a UTFB-equipped fin with these plates can be easily adjusted in the water. No need to fully undo the screws, just losen them a little, the fin can the be moved fore or aft without risking losing the parts.
The STL file is attached. Print using PLA with 100% infill.
Stainless steel hardware required for each UTFB:
M3 x 20 button head socket x 2
M3 hex nut x2
M4 x 10 grub screw x2
Here are the printer setting for Prusa I3 :
See attached screenshots for Slic3r settings.
The solid infill is required at this 5.5 deg angle to allow diagonal placing on the print bed. If printing at a different angle on a larger print bed, the infill angle needs to be adjusted.
A lot of the settings are essential for success. Check them carefully to avoid numerous mis-prints.
The printer needs to be open (not in enclusure) if you want to do filament changes as described earlier. Otherwise layer shifts will be caused by temperature drop when the enclosure is being opened.
If using Polymax PLA single colour, then use enclosure.
Print temperature is basically higher than recommended to achieve optimal inter-layer adhesion.