First Fin

Today I finished my first real fin.  I’d practiced some on plywood, but this is the first fin I made that has a base and that I will actually surf.

The wood was some scrap redwood and fir that I glued together.

I spent a lot of time worrying about how to do the halo.  I used a cad program (Fusion360 because it’s free) to delete everything from the fin model that was less than .1” thick.  I then used my cnc router to cut out all parts of the fin that were less than .1” thick.  (first photo–I couldn’t figure out how to put photos inline)

I filled this with epoxy resin.  (second photo)

Then when I cut out the fin, I had a fin that has a halo everywhere the fin is less than .1” thick. (3d and 4th photos)

Once I had the fin cut out, I glassed each side with two layers of 4oz.  

To make a base, I put the glassed fin in a mold I made out of a plastic cutting board.  (5th photo)

Finally I sanded it, installed the hardware, and will probably surf it tomorrow. (6th photo)

I want to thank Jrandy for helping me (starting over a year ago) with issues on using a cnc machine to foil fins, J3 for showing me how to glass the fin, and to Hans for writing the program FinFoil (without which I wouldn’t be able to do any of this).

I learned a lot by doing this, but any suggestions are welcome.  Soon I will start my second one.






Looks nice!  What does everyone think about creating the halo before the fin is glassed?  That is my question in his procedure.  Screen name “ricky” that surprised me!

Outstanding Ricky! The pre-cut, self-molding halo is awesome.

Thanks for sharing your solutions and success with us. It’s been what, over a year since we PM’d about this?

Now I am hankering to make a fin!

PS -Ricky, edit the first post in this thread if needed until your points are buoyed up to the new lower limit.

PPS -Share the stoke, please give Ricky a +1 so he can get the 10 points to reply without having to start more threads.

 

 

You’re welcome!

The fin looks great, I’ll tweet about it.

Hans

Very cleaver , well done

looks a great idea, and would be even better using the panel for multiple fins at the same time?  may even try a hand held version…

nice job!

i like your little cnc router. did you build it? think it could cut fins out of a g-10 panel?

(can finally post responses–thanks to those who gave me points)

I made the router from a kit my kids gave me; the hardest thing about using it was learning the software (which I’m slow at).  I haven’t seen any G-10, but am pretty confident the router would cut through it.  It can cut aluminum (but not steel), and I assume aluminum is  harder than G-10.

I think I got the basic idea of pouring the resin for the halo from some post on Swaylocks long ao, but have never been able to find it since then.  The hardest part in designing this was figuring out an easy way to make the halo only where the fin was .1" thick or less.  It would have been easier to simply make the halo a fixed distance, such as 1/2", all around.   The way I did it results in a fin that looks the same as laminating wood on two sides of a .1" thick fiberglass panel.

The fin is beautiful! My only critique would be that 2 layers of 4 oz. doesn’t seem very strong considering the grain direction makes it somewhat fragile / vulnerable. I would have run the grain along the angle of the fin rather than perpendicular to the base.

Also don’t know why you would need a computer numerical control to shape the fin, but different strokes for different folks. Hope it works as good as it looks!

http://www.swaylocks.com/forums/wood-fin-halo-build.

I like the idea you have. A resin dam built right in. Above link is a thread on the way I have done halo’s in the past.

Dave Town–thanks for the link–your’s is the post I couldn’t find that gave me the idea.  Re-reading it now, I see that I didn’t cut the slot around the edge, but I don’t think it will matter since the epoxy stuck to the wood very well.  I picked two layers of 4oz on each side rather randomly, and may need to use 6oz if this one breaks.

I am attemping a halo’d gullwing fin via CNC. Directly inspired by Ricky and MrMik, as well as the other gorgeous fins made by others on Sways. Powered by Hans’ finFoil program and other freeware such as OpenSCAD and Draftsight. Respects to all.

I think that the poured halo is a really smart idea.  I’ve made a few fins and for the halo I would leave laminate one side leaving the edge sticking out from the edges of the fin.  Then would add fin rope around the fin edges using the excess laminate as a support.  After cleaning it up a bit, would then laminate the other side.  

It’s always a messy task and I’ve never been able to get a perfectly ‘bubble-free’ halo. I eventually started laminating a 10-20 layer central panel and adding wood layers on either side.  When foiled, the central panel is exposed creating a halo of sorts but not a nice clear one like those shown in this thread. On the other hand, the central panel halo has built-in fiber reinforcement.

This pre-foil molded halo makes a lot of sense. I missed DT’s earlier thread but glad I caught this one. If I had anything to add it would be that the forward edge of the fin is the area most likely to receive impact.  It might make sense to increase the halo width along that forward edge. As is, it’s still a lot better than some of the plywood or bamboo fins I’ve seen with essentially no protective halo.

 

Agreed, your method of making the halo is brilliant…K.I.S.S. Nice going. As for the cnc stuff, that is beyond me. Brave New World.       ps. Next time, follow Huck’s advice on the grain. Put it to your advantage.

Is the cutout not even along the bottom?  In the photo it looks as if the ‘well’ you cutout is not flat at the bottom.  I was wondering if there is some reason for this?

I just finished my second fin made by this method yesterday.  The halo and everything turned out great; problems arose when I put the fin into a mold to make a base.  I stuffed lots of cut up fiberglass into the mold, but there was a weak spot where the front base sticks out from the fin, and it broke off immediately.  I patched it up with several layers of fiberglass, but I definitely need a new method.  I’m thinking I may put the wood fin into a mold with a thinner base, and then glass over the fin and base together, with the glass extending the full length of the fin.

Here’s a photo of the well or moat that I cut out for the second fin, as well as some of the following steps.  (the shape was designed by J3).

 

Ricky, another amazing fin! I think it’s time for me to ask you how it’s done.

How are you aligning first to second side? Does Fusion360 make any part of this easier?

The well on mine was done first, 3/16" in from the outline of the fin and 1/16" past the outline of the fin, starting and ending at the top of the fin base. The stock was .650" thick so I did the well 2/3 of that or .430" . The picture is after the top rout before the bottom rout.

My second side machining ended up a little skewed and tapered to the top. I thought I had the stock square and flat enough to bolt it down without pin registration but this was not the case.

The halo worked fine, the foil looks OK but the base is toasted. I am thinking about either filling it in and grinding it to size or attempting a base mold like Ricky did on the first one. I already have a mold, just have never tried it.

I can add some pics later.

 

 

Jrandy, I sure would like to see any pics you have.  I’m very curious as to what you’ll figure out for the base, since that’s where I’m having a lot of problem.

I haven’t had any problems aligning the left and right sides in fusion 360.  Here is a brief overview, but I could write it up in more detail if you’re interested.  Basically in the CAM setup for the top I have the bit start at a corner, say upper left.  In the CAM setup for the other side (the bottom), I have the bit start in the same place, but since it is flipped over, it will now be the upper right.  When I about to run the program, I first drill all the way through the stock at the place the bit starts (this allows me to place the bit there when I flip it).  Then I tell the machine to go some horizontal distance, say 9", and then I drill another hole all the way through the stock.  Then I cut the top side.  When I flip it over to do the other side, I start by placing the bit at the origin hole.  Then I adjust the stock so that when I tell the machine to go 9" to the left, it will end up at the second hole I drilled.  Once these holes are lined up correctly, the sides will match perfectly.

One thing I am not precise about is the depth, the z axis.  I"m rather cautious, and on the first pass I don’t go to the depth I really want.  If you look at one of the photos I just posted, you’ll see that I drilled some holes through near the top of the halo after I cut the fin.  This is just outside the halo, and I used them to see how thick the halo was at that point.  I didn’t trust myself to do it right the first time, so I ran passes 3 or 4 times, just lowering the bit about 1mm each time.  I don’t want to cut all the way through, because I want the fin connected to the remaining stock for support and rigidity while cutting.  This time I started with a bit thicker stock (about .5"), but next time I will go thinner, maybe 1/16 or 3/32" thicker than the fin.

One difference in our wells is that I think (correct me if I’m wrong) yours is a set distance around the fin, whereas I made mine only where the fin was less than a certain thickness (.1").  That is why the well is wide on the trailing edge, and thin on the leading edge.  I don’t know if that will make any practical difference in the fin; I guess it depends on how big a halo one wants on the leading edge.

 

Yes, this design was for an even distance versus even thickness halo. As one of the pictures show, it does a roughing pass to get close to the intented thickness and then it goes back and does a finishing routine.

My 3rd party machining program sets the zero to be front left top corner of stock for the first pass. In my case that puts the fin base towards front

After the halo pass and top pass, the stock is flipped in the ‘Y’ axis and the same location in space, the new front left top,  is the zero for the other side but the fin base is now in back.

My program also allows me to put in tie-bars to retain the milled piece in the stock, so falling out is ususally not an issue unless I make the bars too thin or too narrow.

Enclosing some pictures. There was a hole in one of the seams at the halo so some epoxy drained out and I ended up firmly glued to the spoil board.

It’s hard to see but the mold has 3 coats of PVA mold release. Hopefully that is enough or I will be firmly glued there too. Maybe I’ll wax it too.

I just got an idea for next time…

 

 

 

 













That looks great!

I wasn’t able to figure out how to do a silhouette cut around the fin and base like you’re doing, which is why I made the mold.  I’ll have to spend some more time in Fusion360 trying to figure out how to do that, because I think your method may result in a stronger base.  Are you using Meshcam?

“There was a hole in one of the seams at the halo so some epoxy drained out and I ended up firmly glued to the spoil board.”

The same thing happened to me the first time, and my spoil board got a bit chewed up.  That’s one reason I made the stock thicker this time.

I made my mold out of an old plastic cutting board, and epoxy doesn’t stick to it, especially if I spray some silicone on it.  But it isn’t nearly as nice as what you have, and I may try to make something like that.  

Thanks Ricky.

Yes, I am using MeshCAM to generate the CNC code from the STL files made in OpenSCAD.

I would have made the mold from HDPE ‘cutting board’ too but I did not have any at home at the time.