did my first finbox (probox) install today (thruster setup). two went well, but one has me concerned about a few things…
when i routed the hole, the bit was set too deep by accident (by about 1/8") and therefore had more resin and kicked with more heat than the other two boxes. just wondering, how do you know when you’ve had a meltout? it felt warm to the touch on both top and bottom (but not hot) and i’m concerned about whats going on inside. (btw, the box was installed with a mix of 1oz lam resin and about 0.5cc catalyst, some white pigment, and milled/cut glass fibers).
in an attempt to address the heat issue, i pressed a wet paper towel onto the install to cool it off, but then realized that some water had soaked into a small gap between the resin and the box (not sure if any got into the foam). this is bad, no? i turned the board over and soaked up some water that seeped out. the fact that there’s water in there to begin with doesn’t make me feel good. should i be worried?
Howzit specialk, Don’t use paper towels, use a damp sponge and place it on the deck over the fin box area, just like with FCS. As for the water, try using a hair dryer on the area and see if any water comes to the surface, just don’t burn the board.Aloha,Kokua
On polyboards, too much resin in a box hole or ding repair usually results in cracked resin and/or discoloration. Cooling it down increases the likelyhood cracking and won’t stop discoloring. With epoxy fills, the foam can melt. If you have to cool down an area, use those small hard plastic “blue ice” frozen packs over a dry folded paper towel (condensation).
Always avoid deep fills with any resin. Use multiple fills or foam saturated with lam resin to build up low areas. On finbox repairs that have to be re-routed, I layer 8-10 oz. cloth until I get the depth corrected. I set the box using milled fibers mixed with only enough lam resin to fill 1/3 up the box, and align it with a fin or jig. Fill the remainder in one or two pours using pigmented sand resin; take care of any air bubbles with a toothpick until it gels.
Howzit Pete, The trick to not having to deal with the air bubbles is to mix up the filler a few hrs or a day before you need it. Those air bubbles come from the milled fibers and the bubbles will come to the surface and burst leaving a nice creamy resin with no bubbles. Just mix it in a container that you can cap to stop any styrene from evaporating and making the mix thick.Aloha,Kokua
Howzit bizgravy, I am sure specialk is using poly since he refers to using catalyst with his resin. Can’t say how it would work with epoxy since I don’t use the stuff myself. Aloha,Kokua
Since we are always doing repairs, I keep on hand a sealed pint container of cabosil/resin mix. When needed, I just mix in an opaquing filler and/or pigment and catalyze. The cabosil I get from my supplier is just foam dust, so the mixture is clear. I also mix it very stiff. Letting the mixture sit for a day not only reduces air bubbles, but it also wets out the cabosil better. Freshly mixed filler will always leave pits when sanded which are the clumps of cabosil that don’t get mixed. If it gets too thick over time, I just add more resin.
