Hi i wanted to share with you all this design i created for a replacement fin for soft boards.

i tried to search for a similar item thinking a STL file was easily available online but failed to find anything close to create a replacement item. So after some 5 or 6 revs later i came up with this design which works well & seems a very acceptable replacement option.

This is just a basic push in softboard fin secured by a threaded 30mm location pin retainer + 36mm long x 30mm wide head screw as a replacement fin for the cheaper softboards, soft surf boards and the soft body boards.

You can buy this items on eBay for about $30 Australian, but hay this is a 3D Printing website & a challenge … plus I’m too tight to pay $30 + postage and wait over 4 weeks for the item.

Step 1: Original Fin I Try to Copy

This is the Original Fin i try to copy,

Some of the thinner more finesse designs were not sturdy enough to justify the printing fail rate and abuse they are going to get during use and in transit. i added a wider load spreading flange & the two push in 30mm threaded locating pins, these were ~93mm apart on my soft body board & surf board.

i tried to search for a similar item thinking a STL file was easily available online but failed to find anything close to create a replacement item.

Step 2: Cura Screen Grabs of the 50mm Fin

So after some 5 or 6 revs later i came up with this design which works well & seems a very acceptable replacement option. This is just a basic push in softboard fin secured by a threaded 30mm location pin retainer + 36mm long x 30mm wide head screw as a replacement fin for the cheaper softboards, soft surf boards and the soft body boards.

You can buy this item in shops & online for about $30 Australian, but hay this is a 3D Printing instructable website & a challenge … plus I’m too tight to pay a minimum $30 + postage and wait over 4 weeks for the item.

i chose this fin design as it is very sturdy (at 13mm thick) and practical for diy home 3D printing.

i created 2 options of fin heights ... ~50mm & ~90mm fin, of course you can cut this fin off and insert any other design you want on to the mounting plate. I suggest you use at least 50% fill for the fins & 100% fill for the retaining screws.

for Cura Set up see the attached screen grab design setup.

Step 3: Optional 3D Print Method Lying Down

You could prin tthis item lying on it's side but i opted for a vertical print with "Everywhere" or "touching base" support.

Step 4: Printing & Clean Up

Using Cura to produce the GCode, I printed in an upright position & used a “everywhere” or “Touching Base Plate” support option, which works well, the main bulk of support comes off very easily with a bit of squeezing and twisting, the only drawback is the internal female thread also gets a support mesh printed inside which needs removed or poked out on completion, I used a combination of 4mm wire, long nose plyers & wire flat head screw driver, but not too big it will damages the internal helix threads.

Step 5: Retaining Screw

The screw is 35mm long x 30mm wide head, has an external size of 7mm thread for the bolt shaft & the nut receiver side of 8.5mm therefore a tolerance of 0.75mm each side which seems quite big & slack but works well. This also has a 2.5mm coin slot for tightening and removing (which is just right for the largest 2.4mm thick Australian 50 cent coin.)

When mounting the Pin + screw it has a total board thickness clearance of ~60mm to ~42mm if you need a smaller gap for a smaller board thickness then cut the screws down by 5mm then retry so you get max thread grip overlap length.

Step 6: Fitting Onto the Softbaord

Fitting was very easy push in fit from the under side and tighten with the screw from the top side,
don't over tighten as it will crush & deform the soft foam.

Step 7: STL Files Attached

See attached the 3 x STL files for anybody who whats to have a go.

I’m always learning so any good constructive feedback or links to other similar items are welcome.

Thanks for reading.

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Notes: Prusa Anet A8. see screen grabs for full Cura set up

My 3D Printer set up & Major Cura settings...
Filament: 1.75mm PLA White
Nozzel: 0.4mm
Layer: 0.2mm
Wall: 1.2mm
Infill: Fin = 50% // Screw = 100%
Extruder Temp: 200oC
Bed Temp: 60oC
Fan: 50%
Support: yes