I have absolutely no idea as to the details of foiling a fin from either wood or F/G. I understand the rough foil geometry (thickness at 30% of cord length). Anyone care to offer a short explanation of getting a nice foil. Thank in advance
Installer, As with any kind of shaping project you start by creating a crude shape by taking material away quickly. In this case you use course abrasives and fine tune the shape by using less aggressive methods so that you don’t loose material where you need it. I start with 24 grit and go to 80 next. The final work is done by hand. Having tools that work well for you setting them up right is the key. Once material is gone it’s too late and the project becomes a repair job. Move slowly and don’t worry about how long the first one takes. Wear plenty of protection and don’t worry if you mess up the first one just keep working it until you have something. If you were shooting at an 8.0" fin and can’t get it right util it’s 6.5" that’s ok. You have to learn hand crafting by experience. Some learn faster than otheres. Mahalo, Rich
I always find it easier to follow a line. The first wood fin that I foiled I scribed lines similar to the way you would set up rail bands. To scribe I used a combination square and traced the outline of the fin at various offsets. For example scribe at 1/2", then 1", then 1-1/2" etc. Next step is to blend these lines into a foil using rasps, surforms, sanders or whatever tools you feel comfortable using. Finish up with some hand sanding. Good luck.
I don’t know if this will be of any help, but here in Australia I’ve heard of guys using a router. They follow the curve of the fin, going progressively deeper as the reach the edge. I would imagine this would require a steady hand but would give quite accurate thicknesses.
I think that the only way to foil a fin with a router would be on a CNC milling machine. A lot of sailboard fins are done this way. I foil longboard fins with a 6" softpad and small fins with a 4" grinder.I mark a centreline around the fin with a pencil, Then I start sanding the trailing edge first, working towards the leading edge. Turn the fin over and do the same. Now do the leading edge. It doesent take much to do the leading edge, just a few passes.I use 40 grit on the sanders 60 80 120 to fine hand sand. It is a pretty hard process to describe hope this helps. David.
You can do it by hand with a grinder or rasps.The trick is to leave a long tail on the fin blank so you can clamp it on a bench.When you finish the foiling cut the bottom of the fin where you want it.In the old days we used to foil glass fins after they were laminated on to the board,it was just part of the sanding process.Again I have to thank Jim Phillips for the clamp down trick. R. Brucker
I have done hundreds of fins - No extra clamp material required, just do the leading edge first, as this will give you a flat section in the middle of the fin still with enough area to clamp for the trailing edge- for centre fins gauge a line with finger and pencil down the centre of the edge. Clamping the base first with the leading edge exposed, make strokes with sander from base to tip. On traoiling edge side, feather the strokes out wider in the tip to give you the tapering desirable for tip flex… http://www.speedneedle.com.au