I need to install fin boxes for a couple longboards but I don’t have a router. I only make a few boards each year so it’s hard to justify the cost. Are there any alternative methods or something I could jury rig? Maybe some drill attachments, Dremel, or one of those cheap roto-drill tools?
As I didn’t have a router for years, this is a specialty of mine… Allow for a slightly larger opening than your box dimensions. Use a metal edge ruler (the backside of a hack saw blade will work too) and position it so the metal edge is outside the edge of your desired hole. I tape down the outside edge of the metal and hold it steady with my hand. Be very careful not to score outside the dimension of your opening - the metal edge is there as a guide and to protect the rest of the board. With a sharp awl or some other type of pointy implement, punch tiny holes in the corners. Using the same sharp awl, score repeatedly along the line between the holes until you’ve scored through the glass. Change sides and repeat until you’ve scored all the way around. Peel out the glass within the scored lines. Take a sharp chisel and go to work on the foam and stringer (unless you have a double stringer with no wood where the box goes.) I’ve taken a spotlight and shined it through from the under side so I can see how deep I’m going. Glass your box in as usual. The only visible difference between this method and the router method is that the corners of the opening will be square.
I’ve done boards before similar to how you describe; I was just wondering if there was a cleaner, easier way using a cheaper power tool. I’ve set the boxes before laminating as well (covering the fin slot with tape and using an exacto knife to open it again as the resin gels). But the big hassle is using the chisel. It’s time consuming and messy and the stringer often cracks and splits. It’s also hard to get a nice clean cut in the foam. Thanks though.
I support your desire to save money by putting extra time into manually cutting out a fin box hole, but there really is no real shortcut short of using a router–especially for the center fin. Nothing compares to the clean cut of a router for such a critical aspect of your board’s performance.The main reason has to do with precision–if you don’t cut your box holes perfectly straight (on the stringer)or with an even depth, you’ll be putting in a crooked box, and attempting to somehow level it or straighten it will only frustrate you, if not ruin your project (a crooked fin is a screwed up board) and force you to take it to a professional to somehow fix it at a cost of money and time that would justify you buying a router and learning to build a jig in the first place. Also, cutting through the stringer with a router is easy. I take my time and make several passes at increasing depths and avoid trying to cut too much stringer out at once (which would create serious friction and vibrations that can offset the jig and burn a hole into the surface of the foam). I use a pretty good quality $15 half-inch wide carbon bit so that the stringer cuts like butter. Because the router is really powerful, you can’t cut a hole without a jig, and that’s another dimension to your question. But in my case, I’m actually using a jig I made out of scrap wood and it works fine with with my cheap-ass Sears Craftsman router I bought for 30 bucks ten years ago. I clamp it onto the tail with rubber padded, squeeze-adjustable clamps I got from a pawn shop for cheap. I practice-cut scrap pieces of foam–even those styrofoam surfboards 7 eleven sells for $2-- before I make the actual effort on my project, and all goes well in about 20 minutes when I really take my time (I know pro board builders would laugh at that but I’m not buying their boards, am I? [smile] This sounds like a fairly involved learning curve–and it sort of is, but putting your fin box in right with one try is as critical as knowing how to shape a blank well and knowing how to glass well. It can make or break the success of your project. But you don’t have to buy a $135 router to put in a center fin box.
Use a sharp chisel and take shallow cuts… it works and shouldn’t muck up your stringer. With careful layout, you should be able to get it right on target. A roto-zip, while being a very handy tool, doesn’t cut deep enough - neither does a Dremel (also a handy tool) - I have taken boards in to a glassing factory and paid for the service of a box rout - ironically, a couple of those came out off center!
Thanks guys. Maybe I’ll just buy a cheap router and tell my wife I need to make new kitchen cabinets or something. I have had trouble with cock-eyed boxes before using the hand chisel method.
a sharp exacto type blade, file and sandpaper should(and will)do it.
kind of off subject, but not really…when you guys put in your fin boxes, prior to adding the resin, does it sit just above the board? if you have f/u boxes, do the tabs rest on the board? i seem to be having problems with getting certain fins in my boxes. i think i am not sanding enough of the box off allowing for a deeper slot. confused yet??
Yes, the tabs will rest on the board unless you install in a thin tail and don’t have the depth to sink the box in completely. Usually you can grind down whatever sticks out and not have much problem - the fin tab/screw may sit a little high but that generally doesn’t matter much. If the fin is too tight, it may be because the box warped while the resin set causing the slot to squeeze in. It’s a good idea to stick some popsicle sticks or something (even a fin)inside the slot when installing - that little brace they mold across the slot isn’t enough. Make sure the fin you’re using is within specs (try it another board) - If it’s OK and your box is tweaked, you can widen the slot with a file or sandpaper on a thin block. If the fin is too thick (it didn’t fit the other board you tried it in) you can sand it thinner. Occasionally the pin is fitted too high causing the base of the fin to bottom out as you try to wedge it in place. Shaving away some of the bottom of the base might help.