Swaylock’s™ Surfboard Design Forum

BEST OF SWAYLOCKS VOLUME 6
Contents: how to set a 10" center fin box; why is my ding repair green?; how to fix dents in blanks; fiberglass cure times; effects of rocker placement; airbrushing tips; making stripes; templating with a router; info about wax types

HOW TO SET A 10" CENTER FIN BOX:
[Doug Schuch ] Make a template out of a decent piece of plywood. 1/2" baltic birch works good. Cut the overall size about the same size and shape as the tail of the board you will work on.(approx.16" long and 6" wide at the bottom, 12" wide at the top. Then cut a slot in the center of the template EXACTLY the size and shape you want the hole for the fin box to be. I recommend 1 1/8"x 10 1/8". That size will allow for some resin squeeze-out and adjustment. It's very important to make the slot exact, with smooth sides, because you will transfer that shape to the board when you cut it. Clamp the template (lightly: just enough to hold it) in place. To cut the slot, use a plunge router with a pattern bit. A pattern bit is a straight cutting bit with a bearing ON TOP of the bit. The bearing is the same diameter as the cutter, and runs inside the template. As you plunge the bit down and run it around the inside of the template it cuts the exact shape of the pattern you've made. The slot should end up a hair over 1" deep. Be careful that the template doesn't slip during the cut, and don't rush it. Some rubber or foam on the bottom of the template will help.
[Mike D.] A fin box tip. After you route out your hole for the fin box, wipe the box with a little acetone (to ensure a good bond with the lam resin). Mix a little hot batch of lam resin (so that it kicks in about 5 to 10 minutes, just enough to cover the very bottom of the routed hole). Drop your box in there and align it. I like to put an actual fin in the box to get a good visual alignment. Get it straight and let it kick. Now you have your box aligned and you don't have to worry about it floating around. If you don't set it with some resin, when you pour in your lam resin/pigment mix it can cause the box to float from the bottom of the hole, throwing off your alignment. (This has happened to me before and it's no fun). You don't have to use any wax additive, it will sand down fine without it. When mixing the batch to fill up the box, don't use too much catalyst. You don't want it to over heat. If so the side of the fin box will swell a little bit and as it cools it will contract, leaving you with a small slit between the fin box and the hardened resin. If you get this, you can come back and fill it in without much problem, but you will get a better bond if you let the resin kick slower. Good luck.

WHY IS MY DING REPAIR GREEN?
[Tom Sterne] Next time try adding some filler and little white pigment. Depending on your choice of filler you may not need the pigment. (Cabosil, milled fiberglass fibers, D.E.(diatomaceous earth of the pool filter type)and even Huggies diaper filler. (don't laugh, do a search in the archives for some of Herb's secrets). The green color is the color of the resin you used, you are putting a thicker layer of it on than what is on the lamination you are repairing and the color is amplified.

HELP, I’VE DENTED MY BLANK – WHAT CAN I DO?
[Grant] I used heat gun, I just held it about 1" to 1 1/2" away from a ding that was 1" long by 1/8" deep. I kept moving it, so I wouldn't over heat one area. It began to rise up like magic. I was careful not to burn or melt the area, since those little guns get really hot.
[Herb] Believe it or not a heat gun will take out some hairy large dents. What it won't take out are: deep scratches, tears, cuts, gouges, holes (either by accident or purposefully). And you can actually depress the foam quite deeply BY OVERHEATING AN AREA. Not to mention a quick yellow to burnt brown meltdown, if left standing in one spot too long. You can also warp your rails, outlines, rockers, tails, etc.

MY BOARD IS GLASSED, HOW LONG DO I HAVE TO WAIT TO SURF IT?
[Sluggo ]If it is standard Ortho polyester resin, it is useless to wait as it will only crosslink so far. The whole "wait for 3 weeks" is an old wives tale. The only way to get a higher rate of post cure is to post cure the board at a very precise time at a very precise temp. Or use UV cure initiator.

WHAT HAPPENS IF I MOVE THE ROCKER APEX FORWARD OR BACK?
[Greg Loehr] In very broad terms, moving the apex up creates more drive and is better in most flat faced waves. Moving the apex back makes the board looser and is better for hollower waves.

MY AIRBRUSHING SUCKS – ANY GOOD TIPS FOR AIRBRUSHING?
[Doug Schuch] The three main things to do to get an even paint pattern are: 1) Make sure the gun is absolutely clean inside. You're dealing with very small diameter holes for the air and the paint. Plan on cleaning it often. 2) Mix the paint, mix the paint, and mix the paint. Water based acrylics tend to stay lumpy for a while when they're diluted with water. Strain the paint through a piece of panty-hose. I know it sounds funny, but it's a very fine mesh that works great, and will even stand up to lacquer. 3) Get the air pressure right (trial and error). Too low and you'll get spatters. Too high and you'll be blowing too much air. It needs to be just high enough to atomize the paint.
[Surfhungry] You need to get your wife’s nylon and strain that paint to get out the clogs, it is a must! If you hate the spray job you can sand it off with a screen, sand pad and air nozzle, just slow down and test the paint or water on something else while adjusting spray. Foam has a static cling to it also, so you need an air current going under the blank or it will pull atomized paint out of the air and on to the other side....
[Indygoofyfoot] I use tempera paint to spray all the time and get good results even through an airbrush. I thin it about 25% (3/1 ratio paint to water). Be sure to strain it! Keep your air pressure under 40psi. Do one light coverage and let it dry completely before successive coats. Dark colors may take up to three coats, let dry completely between coats. By all means test it on broad area before committing to foam. Oh yeah and don't handle it too much before glassing!!!

ANY OTHER WAYS TO PUT COLOR ON BOARDS?
[Eric J] I’ve done stripes by soaking a piece of roving in colored resin and then laying it over the foam and wrapping it around the rail to a tape edge - then lift and it leaves just a bit of colored resin on the foam where the roving has been (If you do this be sure to let the roving drain for a bit after dunking it in the colored resin that way you avoid drips and puddles). I've done this before (in lamination - not on the foam) with clean, white, cotton string - string was a bit easier to handle than roving and soaked up a more even amount of resin along it's length. Roving is always messy and has a bit more memory than string so it can be hard to handle. Stripes worked out fine on the foam with very little in the way of bump or raised surface along the stripe.

HOW CAN I USE A ROUTER TO TEMPLATE MY BLANK?
[Resinhead] I get my bits through Titex tools Inc. Greenfield MA. German Bits, Titex Plus A1622 1/4 inch collet 6 inch long parabolic bit HHS steel. The same bits they use on CNC machines. The trick to no wobble is installing a reohstat. Most routers spin anywhere from 8,000 to 30,000 rpm, thats way too fast, even 5,000 rpm will cause wobble, so slow it down to about 1500 - 2000rpm, no wobble, no tear out just clean profile. Just take your time.
[John@outbreak] Check out www.shapers.com.au and have a look at purpose-built surfboard profiling router bits. Their tungsten carbide "super grit" bits are excellent.

OK, THIS IS NOT A SHAPING QUESTION BUT TELL ME ABOUT WAX TYPES – BASE COATS, WARM WATER, COLD WATER, WHAT SHOULD I USE? (AND DO THE LABEL COLORS MEAN ANYTHING?)
[Ex Sex Wax] Original Sex Wax is still the same. Green=Cold Orange=Cool Red=Warm Tropic=Blue. (Tropic has been blue to indicate the blue waters of the tropics I reckon). Zog changed to Quick Humps to 6 formulae around the time I quit in 2002. Quick Humps has 3 types of base wax and three types of top coat wax. It is a bit confusing but easy enough to figure out if you just spend a little time. If you want the hardest base coat and are going to surf really warm water then Blue or 6x is for you. The harder the base coat the smaller the humps and the longer your wax will stay on, it is also the hardest to put on. If you are having a problem getting the humps to come up then you need a harder base coat. Quick Humps 1x is the softest wax and is made to be sticky for surfing in a contest heat and doesn't last super long. It is also super grippy for very cold weather and water and is the easiest to apply. If you want to get the Quick Humps to apply more easily for a base coat then put it in the microwave for 3 minutes and it will apply much more easily. Basically Quick Humps and Sticky Bumps are the same, I prefer Quick Humps because I helped test it, produce it and sell it. There is no other wax like Original Sex Wax on the market and if you like the way it works it is the best. In Hawaii Sex Wax warm is the most popular. I hope this has helped with your question.