alright so about a month or two ago i made my two of my own blanks with sheets of EPS foam insulation (see here for thread of blanks/first board http://www.swaylocks.com/forum/gforum.cgi?post=346003; ) so i’ve already used my first blank and i want to start with my second blank, but i want to add a stringer. I have a big sheet of plywood that is about 1/8" thick in a sheet of 6’X3’ about. the board a want to make is a 7’2" or a 7’10" funboard though, what should i do? and also, how thick of a stringer do i need? i thought about taking the sheet and cutting it into sections and overlapping them and glueing them so that they’d be 7’6" of so and then cut the blank (which is 2’x8’x3") in half and glue the stringer in there (making sure each half of the blank is aligned. and then after the glue dries, planing down the stringer so that it fits the curve of the blank… what do you guys think? if i’m going about this wrong, please tell me and give me advice and suggestions… -Cam
Make your stringer material like you said. The Deck rocker of your stringer should be flush to the Deck line of your blank.
You only have to trim the bottom rocker stringer supplus. I use a router with a 1/2" straight fluted bit with a jig plate to pass over the stringer. Or you can just use your planner.
When you cut the profile of your stringer - glue the deck (TOP) of the blank to the top of the stringer. This should match. The bottom of the blank can have the stringer protrude pass this blank. Then you will trim off the bottom excess. All Blank companies work off the deck rocker. It’s the starting point of building a surfboard.
I just finished putting together two EPS blanks with 3mm Fijian Kauri (similar to Balsa). I didn’t cut the curves first (silly me) but I glued with epoxy and q cell and then masking taped in five places. In the middle, on each end and two in between if you know what I mean. Brush the glue onto one side of the stringer and one side of the blank and stick together first and then repeat on the other side. Then break out the masking tape. Saves a lot on clamps. As for stringer size I believe you need at least 3/8" wide to have any real extra break strength. Stringers are usually for making shaping easier and that’s about it. Usually.
Using epoxy to glue up singles is OK but it is way easier and actually easier to shape when you use a “softer” glue. Try using Elmers carpenter glue or even Gorilla glue from the local hardware supply. The EPS is weak enough that a killer grip like epoxy is really not needed and when you are finish shaping the stringer, epoxy bits tend to pop out and leave “pebble trails” all over the place. By the way, if you do choose the Gorilla glue ( a moisture cure urethane) make sure you let the thing cure for about a week before glassing it or you run a better chance of a line of bubbles (gas) showing up down the stringer after glassing.
i had thought about gorilla glue but then i remembered that it foams up… what should i do to prevent the foaming? b/c if i let it foam there’ll be a glue foam gap b/w the stringer and the blank…
You really don’t need much Golrilla glue to do the job and particularly if you are not trying to hold a custom bend in the rocker.
The Elmers carpenter glue is actually pretty good stuff as it is a water based polymer that “likes” the EPS it just takes longer to dry than most non-solvent urethanes. (If there was a water based acrylic that was as cost efficient and set time effective as the urethane we use now I would be using it in production.)
That was a while back and I’ve done quite a bite of experimenting since then… I’ve never done a plywood stringer. Seems to me that it would be hard to get clean. Hand plane would kick and bind ect.
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I got some Balsa wood for free and glued it in with 5 min epoxy. I needed three pieces to make a 8 foot board. Just butted the ends together. The problem was that all the balsa was not all the same thickness. Painted in some fake stringers to fix the mistake. Next board I found some one to run my wood through a thickness planner. 5 min epoxy is hard and does not sand very well . Glue ups with 5 min epoxy are fast and can be done with no clamps if you have two people.
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My best results so far have been with PVC plastic stringer. Brand name is Komatex. Use a polyurthane type glue like Gorilla Glue. The stuff expands so don’t use too much and tape off around the glue area. Sands great. It will seep into your foam so you might want to seal the foam before gluing in the stringer. I have done several boards with PVC and Elmer’s ULTIMATE High Performance Glue. I use masking tape instead of clamps.
My friend MarkSSD wanted to do a Balsa and Redwood stringer on his board. We went to the garden department at the local home improvement store and bought some redwood strips. They call it bender board. We got some stuff that was 10 feet by 6 inches. Glued everything up with 5 min epoxy. Learned a big lesson.
EPS is very pourus. Redwood dust is very fine. I can’t get all of the redwood dust out of the foam. Hopefully we can paint it …
