Why do my F/U fin boxes always seperate from the resin on one side of the box? I sand the box. I fill the hole and everything looks great. Come back and there’s a tiny seperation along one side. It happens to me nearly every time. I looked at one of my pro made boards and he apparently has the same problem. Also, how do I get resin into a crack that small so it doesn’t leak? Thanks
Why do my F/U fin boxes always seperate from the resin on one side of the > box? I sand the box. I fill the hole and everything looks great. Come back > and there’s a tiny seperation along one side. It happens to me nearly > every time. I looked at one of my pro made boards and he apparently has > the same problem. Also, how do I get resin into a crack that small so it > doesn’t leak? Thanks Glass over the box after it is installed and sanded down. It’ll last forever.
Glass over the box after it is installed and sanded down. It’ll last > forever. …Paul has the best solution. …You can just fill the crack with a very thinned out, “hot batch” of resin. Superglue will also work in a pinch. …You need to support the box slot when setting the box.As the resin goes off,the box tends to heat up and expand.Then when it cools it shrinks back,this leads to separation in the bond. …Use some tongue blades taped together and shove it down in the box slot before you resin the box in place.DONOT REMOVE the tongue blades until the box has completely cooled.Herb
Next time set your fin boxes with slow-set epoxy. Mix the epoxy with DE (diatomaceous earth), available at pool supply stores and garden supply stores. The mixture bonds waaaaay better than any polyester resin mixture. It sets up a reinforced structure which bonds to the box and reaches into the foam. If you use fast-set epoxy it will heat up and melt the foam.
Why do my F/U fin boxes always seperate from the resin on one side of the > box? I sand the box. I fill the hole and everything looks great. Come back > and there’s a tiny seperation along one side. It happens to me nearly > every time. I looked at one of my pro made boards and he apparently has > the same problem. Also, how do I get resin into a crack that small so it > doesn’t leak? Thanks I never enjoy repairing fin boxes, especially the new through to the deck plugs and boxes. Boxes involve bonding hard plastic and resin to flexible fiberglass and softer foam. This is done in an area of the board subject to heavy use. It is only a matter of time before an errant heel, knee, elbow strikes the area. When this happens the foam compresses and the glass cracks. If nothing is done, water enters,the foam turns to mush and the box comes loose. One of the easier methods of reducing tail stress is to use a stomp pad. A better method is to take your time when installing the boxes. Ignore the claims about how quickly the boxes can be installed. When glassing place an extra patch where the boxes will be on both the bottem and the deck. Don’t cut huge holes. More resin is not necessarily a better bond. A sixteenth of an inch on the sides is enough. Before using the box clean it up. Fine sand it or dip it in acetone. When installing, consider using epoxy. It is more flexible than poly. If using poly add very little catalyst. Hot resin, I believe, is where many problems begin. Pour the resin in stages Let a stage start to thicken and then pour the next stage. After the box is installed follow Paul’s advice and cap the box-bottem and top, if through to the deck boxes are being used. As opposed to taping the slots, pack the boxes tightly with flour and glass the patches over the slots. Wait until the resin hardens before cutting and bevelling the openings. Sorry for going on but I really don’t like repairing boxes that have been installed quickly and carelessly. Hope this is some help. Take care and have fun. Patrick Shannon
Next time set your fin boxes with slow-set epoxy. Mix the epoxy with DE > (diatomaceous earth), available at pool supply stores and garden supply > stores. The mixture bonds waaaaay better than any polyester resin mixture. > It sets up a reinforced structure which bonds to the box and reaches into > the foam.>>> If you use fast-set epoxy it will heat up and melt the foam. Good info, Noodle. I hadn’t heard of that.
Next time set your fin boxes with slow-set epoxy. Mix the epoxy with DE > (diatomaceous earth), available at pool supply stores and garden supply > stores. The mixture bonds waaaaay better than any polyester resin mixture. > It sets up a reinforced structure which bonds to the box and reaches into > the foam.>>> If you use fast-set epoxy it will heat up and melt the foam. Dont use laminating epoxy, it is too hard. I use flooring epoxy for the box and fins. It stays a bit softer and bonds better. I dont use any filler .
Why do my F/U fin boxes always seperate from the resin on one side of the > box? I sand the box. I fill the hole and everything looks great. Come back > and there’s a tiny seperation along one side. It happens to me nearly > every time. I looked at one of my pro made boards and he apparently has > the same problem. Also, how do I get resin into a crack that small so it > doesn’t leak? Thanks Howzit Slim, What I do first is remove the spanner in the box. For the filler I use the same mix I use for FCS plugs. I set the resin off semi-slow which lets some of the mix seep into the foam around the box which makes for a better bond, this also doesn’t heat up the box which keeps the expansion to a minimum. Iused to wrap glass around the box, but I found that that causes those cracks at the front of the box. I put a layer of glass under the box for reinforcement but that’s all. Haven’t had any problems for a long time using this method. Aloha, Kokua
what is the spanner? the only problem i have with the fin boxes are the side tabs. they rest on the glass but don’t allow resin to fill in very well. when i sand the box down there are little divots from where resin couldn’t seep in??
Iused to wrap glass around the box, but I found that that causes those cracks at the front of the box. - Kokua see your post below about long boxes and stringers… this is maybe more critical than whether there is glass around the box or not. Double stringers (one on each side of box) is a good way to go.
I use a hobby tool to route voids on either side of the stringer forward and back from the center box. When I fill the box, it forces the epoxy/DE mix into the voids. When the epoxy hardens, it clamps the box to the stringer on both ends of the box. I set the fin box, Epoxy/DE it in, trim it, and laminate over it. If I were to install a fin box after lamination, I would route a void under the glass, around the perimeter of the fin box. The epoxy/DE mix wouldflow under thhe glass and accomplish the same strength and seal as laminating over the box.
what is the spanner? the only problem i have with the fin boxes are the > side tabs. they rest on the glass but don’t allow resin to fill in very > well. when i sand the box down there are little divots from where resin > couldn’t seep in?? Kokua nailed it.So did paul when he said to over gloss the box.As for the spanner it is the little bridge going across the box slot.The tab problem can be corrected by adding 4 layers of tape around the routed slot…this enables you to get the box in flat and level while elevating the tabs from the surface…R. Brucker
I would route a void under the glass, around the perimeter of the fin box. …I always use a dovetail router bit to under cut the foam…It keys the box to the board…Cheap insurance… Paul http://www.hollowsurfboards.com/
what is the spanner? the only problem i have with the fin boxes are the > side tabs. they rest on the glass but don’t allow resin to fill in very > well. when i sand the box down there are little divots from where resin > couldn’t seep in?? The spanner is that piece of plastic over the pin slot that gets sanded off. I use a catsup bottle to force the resin mix in and around the box to make sure resin fills in under the tabs. Aloha, Kokua