Fin Box Problem

I am using Fins Unlimited long boxes…I set them in with white pigmented resin and use cabosil as a thickener.For some reason the fins fit to tight…almost have to beat em in.What is the deal?Is the resin too hot and shrinking the box or what?When I finally get the fins in I almost have to hammer them to get them to move.Help me please.

I am using Fins Unlimited long boxes…I set them in with white pigmented > resin and use cabosil as a thickener.For some reason the fins fit to > tight…almost have to beat em in.What is the deal?Is the resin too hot > and shrinking the box or what?When I finally get the fins in I almost have > to hammer them to get them to move.Help me please. …Tell me you put a wad of tongue blades in the slot before you set the box?Right?..else wise it’s,Honey,I shrunk the box slot again. …If this is the case or not,you can hand sand the interior of the box to give you alittle room.Herb

Well goddamn, and here I thought I was just a dumbass. I’ve been having that same problem. I too use white pigment and cabosil and I was thinking the same thing about heat shrinking them. I’ve been grinding my fin bases down just enough to get em to slide. My two wingnut fins fit and slide in all of them though, without modification. Seems the worst with cheap plastic F/U fins.

Well goddamn, and here I thought I was just a dumbass. I’ve been having > that same problem. I too use white pigment and cabosil and I was thinking > the same thing about heat shrinking them. I’ve been grinding my fin bases > down just enough to get em to slide. My two wingnut fins fit and slide in > all of them though, without modification. Seems the worst with cheap > plastic F/U fins. Hey we aint dumbasses we are just victims of crap quality control.After posting my problem I went out to the shop and messed around with putting different fins in an unmounted box.Some fit and some didn’t…the cheap molded ones were way off…one would fit and another one would bind.From now on I going to check em out before installing.They pop these boxes out in large numbers and I will bet that no one is paying attention to the end result.

Hey we aint dumbasses we are just victims of crap quality control.After > posting my problem I went out to the shop and messed around with putting > different fins in an unmounted box.Some fit and some didn’t…the cheap > molded ones were way off…one would fit and another one would bind.From > now on I going to check em out before installing.They pop these boxes out > in large numbers and I will bet that no one is paying attention to the end > result. …I use Ofishl center boxes.Most of the time I install them above the glass,no problems,but always check your FU box types,they vary alot.Herb

Posted By: John Mellor Date: Saturday, 25 August 2001, at 10:06 p.m. 1) I like double stringers - wedge or parallel - doesn’t really matter. Once you’ve routed out the hole the box goes in, you’ve violated the stringer integrity on a single stringer board. Your stringer is about 1 1/2" - 2" thick where the box goes in but after you’ve routed for the box it’s down to practically nothing at the front of the box. I’ve seen numerous leaks, stress cracks and even total breakage right there at the front of the box where the impact of a fin hit was transferred right to the front of the box where the stringer once was. Bruce Jones has come up with a neat method of inserting side stringers on either side of the box extending beyond the front of the box to prevent damage from fin hits. 2) I route after the hot coat. Mask off the bottom around the hole. I line the hole with several pieces of cloth to help reinforce the perimeter of the box and strengthen the resin bond to the foam. I also take a level and make sure the routed area is level so resin doesn’t run out the low end. 3) I cut out the spacer or riser that bridges the slot for the fin. I then take the fin I’ll be using and put it in the box. Mask around the top of the slot and base of the fin so no resin gets inside the box. I put the fin in the box so I can make sure the box is straight. It sucks if you end up with a leaning fin because the box wasn’t straight. This also keeps the box from warping. 4) Sand the outside of the box with something pretty coarse to get a good bond. 5) Mix up some sanding resin and pour some in the hole with the fiberglass pieces in place. Set the box in there and work it around until the resin oozes out the edges of the slot and the box bottoms out in the hole. Check the fin for vertical placement and tape it down to each rail so it stays there. 6) After the resin cures, peel off the tape and carefully remove the fin. Grind off any excess glass and resin and scuff a big oval area around the box. 7) Mask off around the oval scuffed area and the top of the box. I try to place the tape as close to the edge of the slot as possible. Glass a couple of oval patches over the box with sanding resin. After the resin kicks but before it’s rock hard, take a razor blade and cut away the glass covering the box slot. Again, try and stay as close to the edge of the slot as possible. The more of an overlap over the edge of the box the better. After the resin cures completely,feather out the edges of the oval patch. I block sand the whole area before glossing and live with a slight bump around the box. This “glass-over box” is sometimes offered as a premium on longboards (the Con Ugly being one) but being such a vulnerable area with leaks, cracks and even breakage being so common, I think it’s the way to go. I tried to include as much detail as I could assuming that people who already know how to do boxes have their own way and people reading this are beginners.

Be a one board a few years builder, I install the fin box with the fin in it to get the angle correct. Taped around it to keep resin from getting in it. I still usually have to remove some resin from the box. I have had to work with undersized boxes and over sized fins in the past. I have not meet a fin box yet that does not need a little clean with a file.>>> I am using Fins Unlimited long boxes…I set them in with white pigmented > resin and use cabosil as a thickener.For some reason the fins fit to > tight…almost have to beat em in.What is the deal?Is the resin too hot > and shrinking the box or what?When I finally get the fins in I almost have > to hammer them to get them to move.Help me please. http://www.viser.net/~anthwind/

I didn’t mean to imply you were a dumbass. Just never saw this problem posted so I thought I was the only one having the problem. Yeah, the molded fins I have are WAY off too.

I didn’t mean to imply you were a dumbass. Just never saw this problem > posted so I thought I was the only one having the problem. Yeah, the > molded fins I have are WAY off too. No problem J.R…I didn’t take it wrong.Thanks for all the input…now we know that it is not our fault.Guess we gotta live with it…from now on I am going to check the boxes before putting them in.Aloha