I am working on making a few sets of double foiled keels out of baltic berch, I made a few templates from fins I had, and ended up choosing the straight keel with no rake.
First off I cut out the fin to rough, I should have paid more attention to the cut I guess, but is there anyway that small cutting mistake will sand out, or should I just start over. Also when sanding I am using 38 grit disc on my drill and it seems to be to rough, or maybe I just dont have a good eye for sanding yet. When sanding the fin what is my best option, to sand from the middle to the trailing edge or from the trailing edge to the middle, what motion do you sand with vertical passes, horizontal passes, or circular motions.
hi yeahjohn. I assume this fin’s supposed to go on a twin fin. I’d clamp the pair together and then sand the cutting mistake out on both fins at the same time - voila, they will be the same. I’d try 80 grit to get a nice outline.
the outline should be the first thing to be true and exact - because once finished it shouldn’t be touched while foiling the fin…
You want your trailing edge to be 1/32 " thick to avoid fin hum. Just keep the same angle when grinding it. I work from bottom to top. You want to essentially make a triangle of connecting bands. What I do is draw mini bands on the fin. 1/4" bands on leading edge in and 1/8" bands on the trailing edge. And make an line ever increment. Draw it out and it helps you visualize your final product. Hope this helps. Good luck post some pics.
Yes the fins are for a twin fin. Thanks for the great advice. I will be working some today on them (dependng on the surf) so I hope to get okay results on the first set. For some reason I never thought about putting the fins together to make sure they are both the same and sanding them at the same time… great tip thanks. Any other tips or basic logic I may be missing please let me know. I’ll post pictures tonight.
If you can set both fins in a vise so the trailing edges form one continuous curve, it is pretty easy to swipe across both fins with one pass of the sander and keep things sorta even. This diagram isn't the same as your fin outlines but maybe gives the idea?
Okay I have a much cleaner template now… but it is taking some time to foil these things. This is after 20 min, I have almost something working. How long does it normally take to foil your fins? How do you get clean lines on the ply? Do you hand sand the last bits, or get good enough to make it look clean with radial sander. Thanks for the tips please keep them coming!
You get clean lines with steady consistent passes with your sander, however, because you're you're using a drill, it will be harder than if you were using a snader/polisher, or even an air powered sander. Hard not to get wobbles when using those drill attachments, because your hands is too far away from the work to keep it steady. You're doing well though. Get them close, then finish by hand. They'l look unreal when glassed!
Okay, thanks. If I buy a sander, will something like the palm style Skill 5" random orbit sander work okay? or should i just stick to using the drill attachment and then hand finishing for now… is the learning curve going to be minimalized that much? or will I be in the same boat with a better tool? Thanks again, and yeah I can’t wait to have these ones glassed and to start another set.
I dont know what that is. The ones that look like angle grinders, they are great for fins. I've only made a few, but i started with the drill attachment like you have, and then swapped to a pneumatic sander ( passed time on night shift!! ), and it was much easier to get smooth clean lines, you have more control IMHO
I use a 6 inch random orbital sand. I hold the fin in my left hand(with a heavy work glove) and the sander in my right. I can change the angles of both as needed. Takes a while, though. About 1 1/2 hour for a set of keel fins. Be sure to wear the glove if you give it a try. That sander can take skin off fast! Mike
get some wood with thinner plys so that you have more foil lines. that will make it much easier. after foiling with the machines, use a hard block with 100 grit and then a folded piece of sandpaper in your hand to finish them off. you can put some 220 on your machine to get the final scratches out. try some fiberglass or g-10 panels as well - much easier to get a proper foil - but way more itchy!
grasshopper. Thanks for the tips. Wouldn’t wood with more plys be thicker? These fins essentially are just like fins I have on another board just a without rake, and I am just trying to copy the double foil those fins have. I also have a set that is a little more rounded off the back that I am working on. My goal is to create a few fin options for a board I am shaping, then to choose before glassing. Every time I sit down to work on the fins a feel a little more comfortable, and I guess once I get them pretty close on all sides I will hand sand them. I have a drill attachment but if I were to buy a tool what would help me more at my level, the grinder or the random orbit sander? I would just pick up the $40 version at home depot. Thanks again guys.
more thinner plys give you same thickness but more layers. you can get some good ones from hobby stores/art supply stores. or glue up your own with wood or bamboo veneers.
do like girvin says and get a 7" variable speed tool with a spindle that will allow you to put any kind of sanding pad on it. you can buy a good one if you want one to last with you as you progress or a HF cheapy will do the trick too.
