I used a homemade nut on my fin screw, one that was all metal instead of plastic with the insert, and it appears to have cost me my fin and half my fin box. Fin hits coral, metal nut rips out half the fin box. bye bye fin. The good thing is the piece of fin box came out very cleanly, didn’t take any foam with it to speak of. Having ripped a box out of a broken board last week on purpose to have one on hand, I have a spare, but this was not easy to do. Does anyone have a good way to get an old box out of a board in order to replace it without ripping out half the foam and stringer under it? The only thing I can think of is to clamp a frame around the broken box as a guide for a router with a milling bit and then square the corners somehow. Any advice would be appreciated.
Your router idea sounds pretty good to me… Darned finboxes - start coming loose when you don’t want them to, and won’t come out if you do want them to… though I guess once you put them in, you don’t really want them coming out again… I was thinking you could put a fin in the remainder of the box and rock it back and forth/side to side. The box might already be loose from the hit that broke it. Though that would have the effect of compressing the foam next to the box… leaving more space that would have to be filled with Q-cell or the like… Back to the router idea? Dunno how burly those boxes are against a router bit. Never had to dig one out. Guess if you can sand them on install though… Probably best to take it down a bit at a time rather than full depth all at once. Good luck!
Real close - if you use a fairly small diameter router bit ( carbide is preferable) you’ll find that the fin box corners are not exactly corners: they are slightly rounded to be easily and well installed using a jig and router in production situations.
Watch out for the router ‘jumping’ when you hit a hard spot: I’d suggest going about 1/4" deep, then 1/2" and so on until you’ve got it done. Use a fairly stiff piece of wood ( 3/4" good-grade cabinet plywood is nice for this) for your jig, it won’t get pushed around when you hit a hard spot. Also, there are lots of discussions on this ‘fin jig’ subject in the Archives/Resources.
I’m not sure what you mean by a milling bit. But the jig is the way to go using a straight cutting pattern bit (bearing on top). And, as suggested, cut a little depth at a time, because the finbox material is relatively hard and it heats up when you cut it, melting and trying to grab the bit.
If your jig is the same size as the original cut out for the box, you’ll end up with a nice clean, original sized slot for the new finbox. Good Luck. Doug
Roirat, By the way, those plastic tabs are one of those great engineering ideas that have questionable success in the real world. The idea behind them is to save the finbox in case of impact. The screw goes into a little female threaded brass insert that is designed to crack the plastic and release the screw when the fin whacks something. The problem is that they are too weak, in my opinion. If you even over tighten the screw, it will crack the plastic, and while you’re out surfing, making the bottom turn of your life, the fin might decide to say “Bye bye”.
I’ve lost one $50.00 dollar fin and almost lost another one, because the tab decided to let the fin “Go…be free. Swim with your sea brothers”. Anyway, it’s metal tabs for me from now on. Doug
There’s tool out there called a rotozip or dremel advantage that’s perfect for the job. If you put a guide to run it along on the board you can end up with a perfect cut with the right depth and perimeter to set a new fin box into with a wooden stringer in either side of it to add some structural integrity. You want to be sure to wrap the new fin box with a couple of layers of 6oz. as you set it in. Put a small fin orsome kind of plug in it too make sure the fin will set perfectly vertical in it when it goes off. After you sand it down to the right heigth be sure to cap it with layer of glass before you put you finish coat of the area you’ve had to rework. It’ll be better than new when you’re when.
Short cuts always result in failure but when center fin boxes are put in right they hold up just fine.