Surfboard fins

I’ve always wanted to try designing and printing surfboard fins so I did.

Had a few issues getting them to print. The first two prints failed because some supports didn’t print (still haven’t sorted that out yet) but I managed to position and rotate them around and test a few different ways of printing them till they worked. Mostly happy with the prints though there was a noticeable amount of distortion in some directions. Not so much that they didn’t work but enough that straight lines were clearly a bit curved. So far I’m blaming this on the support strength but I also get the feeling that the form 1 does not always print perfect cubes based on some users postings. Maybe this is just support settings but maybe it’s also just the way the printer works with the peeling action pulling on the still freshly cured resin?

Any way I managed to print a complete set of my wacky foiled quad fins. I went with a fin design you can’t easily find and pushed it a bit to try and make something I couldn’t find to buy. I’m just an average surfer and only know just the smallest amount about fin design an a tiny bit about areo /hydrofoils so I was not really expecting these fins to work well but the 2 and 1/2 sessions I got to ride them before I snapped two (either leash caught during wipe out or hitting the bottom on a duck dive in a shallow area)  I really had a blast. At some point I’m going to print out two replacements as well as tweak the design to try and add more area and a bit more strength to try and make them last a little longer. Probably also try some really strange ideas out.

It would be great to have a stronger or maybe more flexible material to try out. One thought I had was to try printing with some chopped up fiberglass cloth in the resin to see if that might add some strength. Mostly I have enough issues getting my bigger prints not to fail and fine fibers in the resin seems like asking for more problems. But maybe I’ll work up the courage to give it a try at some point.

Here is a picture. One side had the super thin back edges fail so I sanded them to a more rounded back edge. I think that’s probably a better design than what I tried so I will probably try and get that in the next version intentionally.

Hey, Great to see!! I was thinking about this too. One of my friends who is a shaper suggested resin alone wouldn’t be strong enough and after snapping my fibreglass fin bottom turning in bali a couple of month ago I would probably agree. I was thinking about printing moulds or seeing what else I could do. Really looking forward to getting my machine one day…

These look great, Jimmy. What are the dimensions on the fins? Some dimensional distortion is more likely on larger parts, but we’re working to resolve those issues through software updates and revisions.

As for strength, well, I’ve seen boards snapped in half. You can download the datasheets for our resins here: That should give you some sense of their relative strength.

A friend wants to try making a mould from them so we can cast them. Probably a good idea since the resin does seem less strong than would be ideal. Totally works but I’m sure they could be stronger. Seems like an easy way to try out designs before committing to casting anything. I was also thinking a think layer of glass with cloth or maybe even carbon-fiber would probably make them a lot stronger. Though casting and glassing are much less immediate and fun than just printing the fins, dropping them in and heading out for a surf.

Can’t remember the dimensions off hand but they were as big as I could fit in the print volume with the foil the way I designed them. Well maybe I could fit a little bigger fin but not much bigger with that shape. I think a regular type fin (no foil) would easily fit in the print volume even for a larger thruster or quad type fin. A longboard keel fin might be to big for the form 1 though. I was able to fit one big (front) fin and both smaller back fins into one print which was cool because it meant I only had to do two prints for all 4 fins not counting the first few failed tests prints.


Are you post-curing them to get the extra durability?  Based on the datasheet, post-curing adds quite a bit of durability that might help you out.

Yes and no. I did leave some of them in the sun for a while. Not a long time maybe an hour or two. I also have a UV setup to help cure/dry parts a bit faster when it’s dark, cloudy or rainy out.

It seems like the extra curing does stiffen the resin up a fair amount but then it seems like it’s more likely to snap with added pressure. The less cured parts seem to have a bit more flex to them. Maybe the next set I’ll try curing in the sun for a lot longer and see how well they hold up.

Still I think that this resin alone probably isn’t going to be as strong as a regular surfboard fin so I’m going to try and make them a little thicker in a few places than they are now to see if that helps them last longer.

I was thinking about printing some fins for one of my boards too. Its nice to see that someone else has that same idea. I was wondering if the little horizontal wings on top should only be on the rail side, not the stringer side? I don’t have any knowledge about hydrofoils, but they are interesting. You might consider creating a hollow cavity inside the fin to make space for a carbon fiber insert. I think that creating a mold is the way to go though. The plastic alone does’t seem durable enough. If you consider that fiberglass/Carbon fiber is used to reinforce the “resin”, then it should follow that the Form1 resin should also be reinforced. By the way, what CAD App did you use to create the foil? Thanks!

There are a lit of good ideas in this thread. I would definitely leave them out in the sun for a couple of days before using them (just make sure all sides get exposed). This post-curing will make a much stronger fin, though they will yellow. Even just leaving parts on my desk for a week, I notice they get harder and have a better feel. I’d beef up the fillet at the top of the T (if that’s where it broke) and I think the idea to 3D print a core and laminate with fiberglass sheets would be the strongest composite design. Adding fibers to the resin is very unlikely to be effective.

Snapped fins can be really sharp (I still have a scar on my ankle from one!) so making them as strong as possible and inspecting them for damage often is a good idea.

I thought about adding the foil on just the inside or outside of the fins but figure I could get more surface area and strength if they were supported in the middle. I was also thinking if they have much lift at all better to have it push straight up on the fin than to push from one side or the other which I would think would put more stress on the fin. Having the foil even and symmetrical on both sides and with the lift pushing straight up the fin which is probably less likely to break if three was much pressure on it. Any way that was the logic behind the foil design and placement.

I actually think it would possibly be a more practical design if the foil was on the inside pointing toward the stringer. That way it would be more out of they way when you swing you legs/feet near it and also less likely to catch the leash. I have a feeling the two fins I broke were from my leash getting caught when bailing on a wave. I noticed the leach getting hung up on them much more than my regular fins. Also I did notice I bumped the foils with my leg walking out the first time when I put the board next to me just before jumping on it. So for those reasons if I try a single sided foil I would probably go for the inside first. The fun thing is with the printer I can try it and if it doesn’t work out I can try it the other way.

I really should just glass the next set I make and see if that makes them hold up longer.

Also think I should really round out the foils to make them less likely to snag on anything.

If I find a design I really love I’ll probably end up making a mold so I can make more cheaper and get some fiberglass or carbon fiber cloth well imbedded in them.

Hey Jimmy how about a trade? What you need is a set of ABS printed fins to test. I’ve been waiting for months to get a few test prints done on a Form 1 and saw your post and it peaked my interest based on what you are trying to do. I think a good test would be a set of fins printed in ABS. i think they might work well right off the machine. No molding & casting. I have an dimension SST1200es a professional FDM NOT a MakerBot toy. Are u interested in a trade?

What kind of trade? ABS fins for Form1 fins? I do have an okay ABS FDM printer but the max layer res I can get is 0.15mm. Looks good at that res but the way FDM prints I think the fin would weak along the axis that the layers are on. I find that though most of my prints on that printer are strong they are always weaker along the layer axis. The way the Form1 prints it seems over all better fused in all of the axis though maybe the layer axis is still weaker.

Currently I am unable to print anything on my printer. Still trouble shooting it as I have time. I have one more thing I want to try before putting in a support ticket. If I get it printing well again (the first prints I did on my form 1 went really well) we can talk about some kind of trade.

Hi Jimmy, thanks for the responce, I’ve been chomping at the bit to get a couple samples done on a Form 1 to see if it would meet my needs. I’m a toy sculptor, model maker, toy inventor. I’ve been pestering form labs for months for a sample but they just don’t have samples yet, kind of bad business for a company trying to sell 3d printers. Anyways what I had in mind is you print a few samples of my models & sculpts and ill print a few board fins for you. I can send u screen shots of what I want to have printed. I was thinking you could you cut the perpendicular top part of that fin design off and cut a tap hole in it so you could print the parts along the flat axis of the fin parts in order to yield the strongest part for an FDM application. Then tap and assemble the top part of the fin even use some weld on to help the bond, I think it would be worth a try. Or print a more standard fin design. I found your post interesting because I use to do some surfing back in the day,but am now consumed with motocross. Anyways let me know if your interested.

I might be interested but after putting in a support ticket with formlabs and a bit of trouble shooting and some tests they had me do they determined that my printer needed to be replaced. I just sent it back and am waiting for my replacement printer. Once I get the new printer and make sure it’s working well I might be up for a trade. What is the print area of your ABS printer? If it’s larger than my two printers I have been wanting to try a fin similar to what I made but a little bigger. I had to scale down the size of the fin to fit in the volume of my printer(s). With a few more inches of print volume I could print the size fin I would really prefer. Though it would still have the same kind of foil design and I would prefer to keep it as a single print rather than attaching the foil even if it’s a bit weaker than it could be. These are more for experimenting with before going and doing much more work to make more solid versions. The fins I printed worked great for almost 3 sessions which was more than enough to see if they worked. I have some design changes I want to try. But other some minor modifications to the current design the thing I really want is to print them a little bigger which I can’t do with my printers.

If you are still interested in a trade let me know and I’ll let you know when I get my replacement Form1.

Ya keep me posted when you get your replacement and well go from there. You can email me when ur ready at bntstudios at verizon dot net My printers volume is 10x10x12 inches. Your the second person on here I’ve read about having a printer replaced, I hope it’s not a bad sign.

Ya keep me posted when you get your replacement and well go from there. You can email me when ur ready at bntstudios at verizon dot net My printers volume is 10x10x12 inches. Your the second person on here I’ve read about having a printer replaced, I hope it’s not a bad sign.