Repairing a buddies FCSii box in an EPS board and have a couple ideas I wanted to run by the SWAY Community.
Whats your favorite way to repair a busted box? Here’s a few of my thoughts on the procedure.
Idea #1 Would it be as simple as it seems to dremel away damaged glass, as seen in pic.Cut out the metal bit in the FCSii box and then put the jig over the board and route as if nothing was there already? drop the new box in and fill any voids with filler and resin. 2 foot ball shaped patches staggered in size. feather and sand coat. Any issues with routing the plastic? (I have a spiral cutting bit on my plunge router that I think in theory would be good at mowing through the broken box)
Idea #2 Make a jig slightly bigger than the box. route that area out avoiding the metal pin in the fcsii box. yank the box out. (I believe up to this point to be pretty common practice) But heres where I may be over thinking it. Is it better to plug the routed hole with PU foam for strength purposes or is it recommended to use EPS for consistency? I have a lot more PU scraps then I do EPS.
As always, any advice and thoughts are mucho appreciated!
I’d try digging out the old fin remnants and give the box a good looking over. Use a bright light, reading glasses, and a dental pick or sharp tool of choice to probe inside the slots. A screw driver could be used to pry gently against the inside of the slot to try and find any hidden cracks.
If the box checks out OK try drilling several small holes around the box and inject resin with one of those pointy syringes or a regular syringe with a 16ga-18ga needle. These can be purchased at a local veterinary/farm supply place. Insert a fin and eyeball for cant - tape from tip to rail edge to hold it in place.
It would still be a good idea to sand off any loose fiberglass and cap the whole thing with a layer of patch or two. Skip the foam plug… seems silly to just reinforce the one when the others don’t have it(?)
I’ve used this method on full length center boxes and various types of plugs. The key is inspecting for damage to the box itself. It looks like the tabs might have done their job and sheared off without breaking the box. If box is cracked, bring on the router. Removing the metal pin and routing along the edge works. Don’t try to route too deep in one shot - multiple shallow passes with increasing depth works. With a bit of luck, that repair might be nearly invisible.
I always do Option #2. Rout an over sized cavity and fill it with a PU plug (I use high density skimboard foam). Countersink the plug (very) slightly and feather the edge of the existing glass job so the the new cap will blend in well without a lot of drama.
I don’t install finboxes or plugs into EPS anymore without installing a high density PU plugs in the blank prior to shaping. Time consuming, but effective. (sometimes it’s good to be a strictly amateur backyarder with the luxury of time) A well supported plug or box cannot twist or flex.
I take out boxes like that with a Stanley knife and a pair of Needle Nose pliers. Eliminates the opportunity for a Router to jump and screw up foam around the box and prevents flying pieces of plastic from wedging in ones forehead or eye.
