Questions about making our own fins, please

General Discussion
1

I want to make some single, sidebite, thruster, and quad fins for FCS, Futures, and US long center fin boxes. I’m thinking of making the fins with solid wood cores because wood looks beautiful and it should make the fins lighter. I’ll be using polyester resin and the 4 oz S cloth scraps I have laying around.

I have a few questions, please…

  1. Since a single fin for a long center fin box is around 3/8" thick…    A) How thick do you make the wood core?    B) How many layers of 4 oz cloth do you add to each side of the wood core?

  2. If the fin and the base are shaped out of the same piece of wood, how do you deal with layering the cloth around the base sides and bottom so it isn’t hell to sand later?

  3. Or do you suggest I make the fin and base seperately and glue them together? If so, what do you make your bases out of (for FCS, Futures, US long box) and how do you join the bases to the fins?

  4. What do you use to make the stainless steel pin for a center fin that fits a long Bahne/Fins Unlimited style box?

  5. What would you use to make the fins a light transparent black/smoke color? Add a bit of black tint? Is it true that you can use food coloring with polyester resin?

Thanks!

2

Before someone else elaborates, my advice is try everything. You will break things and curse the sanding, but you will learn more for yourself, and most of all learn what works and what doesn’t. Really, it’s good fun.

3

I hear ya, and no doubt I will learn a lot, but it would be nice to not have to totally reinvent the wheel, hence the questions. :slight_smile:

Thanks

4

I am with Wildy.
All of those questions seem to me to be of the trial and error variety.

The pins are called “roll pins”. That should help you search at least

5

Thank you, that helps a lot!

http://www.ebay.com/sch/i.html?_odkw=ro+roll+pins&_sop=12&_fspt=1&_mPrRngCbx=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR1.TRC0.A0.H0.Xroll+pins.TRS0&_nkw=roll+pins&_sacat=0

6

Hey Magenta, In the past when I’ve been in a hurry and had nothing else on hand I’ve used brass wood screws for the pins. Just cut off the thread and used the smooth shaft bit. Worked fine for me.

7

I made some fcs side bites before. It was pretty easy I just laminated a fin panel with I think it was 25 layers of 6oz. Then cut & shaped the fin. The cant is built into the boxes so you can just make the fcs tabs flat. Futures sound like a headache to me because the cant is built into the fin. 

8

I’ve built lots of wood fins for FCS and FU 10.5 inch boxes, and I have not used the same method twice.

 

Plenty of failures.  Lately I have been making tapered grooves with an angle grinder withcut off wheel into the fin bases and filling them with roving, But this adds a couple more steps.

 

One of the best ways I found for A 9 inch single fin was running the cut out fin template through a table saw on a slight angle twice along the base so that the middle was only 1MM thick and the taper ended about 2.5 inches up the fin.  This makes foiling the fine harder, and it is hard to run through the tablesaw when already foiled, unless one makes a Jig to hold it perpendicular to table and parallel with blade.

 

I’ve also laid tapered wood bookleafed wood cutouts on either side of a thin fiberglass panel, about 8 layers of 7.5 oz, but this was not quite thick enough for the center, but the tip flex is awesome.

 

One fin I sandwiched  some warped zebrawood between two pieces of waxed glass with several  layers of 7.5 oz cloth on either side.  Unfortunately I should have waxed the glass more than once as it got sutck on one portion and peeled from the wood over 1x1 inch square.

 

But overall that fin came out great, in shape.

Acheiving clarity of the wood through many layers of fiberglass has been my issues.  I use epoxy, perhaps it was nto warm enough, or I worked it too much pushing in micro bubbles and perhaps the fiberglass I used had absorbed too much humidity too, or maybee I just need to get a vacuum system going.  Sure would likely eliminate a few steps.

 

I think my next FCS  base fins are going to be a fiberglass panel in between two pieces of  a lighter more flexible wood, rather than the dense hardwoods I have been using, and I’m making them thick, at least 3/8".  At that thickness getting some tip flex is my worry.  I do weigh 220Lbs .

 

If you are using wood into the fin bases, make sure the grain of the wood enters the tabs at  75 to 90 degrees, base and is not parallel with it/them.

 

 

Last fins I made, i inlayed roving into a groove I cut along the perimeter of the fin’s template. Since they were smaller trailer fins, I cut the grove into the fin base.

When fitting the fins into the receptacles, do not rely on the grub screws or the roll pin and fin plate to make the fin tight in the box. The Fin should fit Snug, and the hardware used only to keep it in place. That is my opinion, and I’m sticking to it. I’ve made a bunch of fins made to fit tightly into a stretched/worn FU box and they will not fit into another board unless I sand them thinner.

Overall fin making is a huge amount of work, and I could never ever actually sell one and pay myself more than 1$ an hour. Labor of love if using wood.

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9

I prefer the following method to create wooden fins.

For symmetric fins, use the following layup:

  • plywood
  • glass panel
  • plywood

(for flat fins, skip the plywood on one side)

This will create a strong solid fibre halo as shown in the finFoil drawings below. (red = wood, white = glass)

This halo, significantly improves the durability of your fin. Less chance of water intrusion when hitting something.

Sorry for the bad picture, it’s the only one I have at hand.

The glass panel functions as a nice anchor, when casting the tabs or finbase. However, the tabs still needs outside glass for stiffness and breakage strength.

10

I answered your questions in bold.  Side note here.  Each wood fin maker has their own way of making the fin.  So much truth in developing your own method.  I personally made and failed at several wood fins before I developed a method.  After that I was taken under the guidance of John Cherry (I consider the most talented wood fin maker) and taught his method.  Even after that I modified his methods a bit.  There is no one perfect way to make fins.  

Be well,

Dave

11
Glenno - Good idea using for using stripped brass screws but I think I'll do the stainless steel roll pins at eBay since they are so cheap.
 
wrcsixeight - All good stuff, thanks. Your idea of putting roving into a groove to strenghthen the tabs is excellent because I was wondering how I would do that.
 
Stayrelaxed - Okay, 25 layers of 6 oz is good to know if I don't do wood cores. Thanks! I'll be using 4 oz S just because I have lots of leftover scraps so it will be interesting to see how many more layers of 4 oz I will need to lay down verses 25 of 6.
 
hans - I want to do "halo's" cuz they look cool and good point about them protecting the wood. A couple questions come to mind...   A) How many layers of cloth do you add to the outside of the wood?   B) Do you cast the bases/tabs or do you cut the bases/tabs to the proper dimensions and then glass over them?
 
warrior1515 - Wow, tons of great info there and thanks for sharing the link to your excellent fin building thread! Nice craftmanship too! I have a couple questions for you too.   A) Regarding the USPS box you used for the halo mold...  I see the box, and I see that you cut the cardboard so it's 1/4" wider than the outline of the fin, but how did you make the outline of the mold and the walls of the mold?   B) I was planning on using the 4 oz S cloth scraps I have left over. Is there a problem with using 4 oz cloth instead of E?
 

 

12

I layered up 2 or 3 boxes to build the thickness.  Then to get an outline larger I placed marks along the outline of the fin and connnected the dots.  You can use green tape to seal the walls of the cardboard.

You will see the weave of S cloth on wood.  Other than that you should be good to go.  

Dave

13

His name escapes me, but theres a great guy on here who mostly does fins. In the past I had some questions about fins and he was a great help. I think he went by chipfins or something similar. 

 

Anyways, my best advice is to just tinker with it. I had my best luck with Suncure resin, a small resin roller, and a big pile of scrap some guys down at the boatyard were throwing away. I made tons of fins and just messed around a little. That experience of just kind of messing about and trying stuff was the best type of learning I could have had. I never was too good at making wood core fins, so I wont chime in there. 

 

Quick edit: I tried making a base seperate and everytime the dang thing snaps off. Maybe youll have better luck but no mix of epoxy poly or filler would work for me. As far as the wooden core goes, I found that cheap wood is bad wood. Low quality plywood was a nightmare. I know a lot of guys use marine grade plywood, so maybe try that out. Ive also heard that balsa wood makes a great wooden core, but dont hold me to that. I would definatly test on a scrap piece first. 

 

Wear long sleeves and a mask. 

14

The fins in the pic are used as glass-on fins. I didn’t do any tab casting yet, but it’s on my todo list. The fins outlasted the board, unfortunately can’t find more pictures.

I used two layers of 6oz on outside.

These fins were a test for one of the early versions of finfoil.