Nat 64 - Reckless Play With Natural Fibers

This is an ugly, junky experimental board. If this is your first encounter with my work, then great! Check this out. But also look at the other boards, which aren't quite this crude.

These are tests with natural fiber cloths.

On the bottom is a single layer of cotton muslin. It's easy to work with. The weave is just tight enough that you can pour a small amount of epoxy directly on the dry cloth and quickly spread it, without it dripping through. It takes a lot of little pour-spread, pour-spread movements, but it's much faster than the brush technique I'm using with fiberglass.


That's the finished lamination. Good results.

We know cotton doesn't have the strength or impact resistance of fiberglass. I easily dinged the rail throwing the board in the van the first time. Had it in the water about 20 minutes before noticing. So this board has already gone through a dry-out and repair cycle.



Got a little help here on the quick patch job.

Though weak, muslin might have a role as a first lam material, since the wet-out technique is faster, and the finer weave will reduce pinholes. A second lam with something stronger might give back enough impact resistance and stiffness to balance it out.


On the deck we've got a base of fiberglass, and then full coverage with a layer of silk, with burlap (jute) rail patches (from green coffee bags).

Silk traps bubbles underneath when you try to apply it as a second lam. Don't know if there's a way to work them out through the fine weave. Silk seems too limp and droopy to lay directly over the core for a first lam. And silk isn't good at conforming to the compound curves around rails - it wants to fold instead of warp, and won't stretch. Not pleased with the silk. Too fine and tight.

But burlap is great - raw and loose. It's a great way to build up a thick section. The thick fibers and loose weave can work as traction if you don't fill the weave all the way with hot coats. You can try to saturate it minimally, or just keep pouring resin into it, depending on what you're after.

It's brown. It's crude. It's functional. I'll be using it again.




Yeah, this is a single fin fish. Haven't heard any advocates for this kind of thing, probably for good reason. But you've got to try it to know.


As long as we're doing things wrong, let's really do it wrong. A 7.5 inch epoxy-sawdust holey baby hatchet. (The first board I've made with some kind of accommodation for a leash - seven, in fact.)


Instead of fiberglass strands (fin rope) along the base, tried some jute twine. Too crude, twisted, stiff and lumpy. At this point I'm done playing and just want to get this in the water. The divot at the front of the base got filled and faired with wax. Let's get it wet.



Still nice with light behind. See where the two missing pieces go?

Fish 64 Build

Recent Fish 64 build.
3 a.m. and I want to get these photos done, so no suburban paradise yard shots this time.


Don't think that left fin is really that crooked - but maybe it is. No - just checked again - both fins are pretty much straight down and straight ahead - and meatier than anything you'll find at the supermarket.


Cosmetic flaw, in unflattering light, and then the same section backlit. There's a point when the epoxy is fluid enough to saturate the cloth, but not enough to fully saturate each fiber of the cloth. There's plenty of warning beforehand - you notice that it's getting thicker and taking longer to sink in. Don't push it - just dump it and start a new batch. Otherwise you'll get one of these embarrassing white stripes. Seems to be structurally sound - it's just not the look were going for. It's on the deck. Conceal with wax.


First vent install I've done. Looks okay on the deck. To hold the vent plug flush with the deck as I glassed it in, I supported it on the bottom with a little paper and tape tube, which will peek out the bottom like this forever.

Hard sharp rails on the tail, for the first time. Learned how to do that from Make Magazine #19. More old plywood fins - NACA0008 foils carved with the router. Figure it's 50 year old redwood alternating with some other pale pine.


Backlit.

Rib Squish for Simmler

Maybe you noticed there's a mini Simmons design on the surfcorr album (Simmler), but no kit available. No? Didn't notice? Didn't even know about surfcorr? Go check it out, then (and read the liner notes). Simmler is the current R&D subject. Cutting now.

An hour into cutting, noticed the notches were coming out in two different sizes. Usually they are all the same. Checked the collection of parts cut so far and they all had the same problem. What now?

Ahh, but that's not a problem - that's rib squish. Prepared these files months ago, and forgot that Simmler has a core pattern variation that requires different notch sizes.

Rib squish: Compare the quarter isogrid pattern above to most of the other board core top views, and you'll see that the diagonal pieces have less slope to them. The pattern is kind of squished in the direction of the stringers. Normally, all parts intersect at the same angle. But with rib squish, you get two different intersection angles, so some notches have to grow and others shrink.

Why rib squish for Simmler? I forget why. Think it was just time to try it. It looks like I also spaced out the stringers wider on Simmler, so it has two fewer stringers than other short boards. Squishing the ribs keeps the hexagons from getting too big in this case, and makes up for some of the lengthwise strength lost by having fewer stringers.

If you look at the art for Glass Fish on surfcorr, you'll notice the center board core has negative rib squish - or rib stretch. The point there was to get the core pattern to fit better in the tail section.

Retractable Pen

Retractable pen mechanism for the router, for numbering parts. It uses skate bearings on a central hollow tube, the pen fixed in one end of the tube, and a plastic zip tie fixed to the other end, connected to a wheel on a servo. In the down position, the pen is free to ride over irregularities on the surface, since there's some springiness in the zip tie that pushes the pen tube down.

It's got 2 inches of vertical travel. When the pen is down and writing, the router bit is about 0.5 inches above the material surface. When the pen is up, and the router is cutting, the pen is about an inch above the surface.

Auto numbering with this mechanism was supposed to save time, but it ends up taking longer than doing it by hand. It's worth it for the neat numbers, and the ability to make any other kind of mark on the surface and cut during the same run. This makes router production a bit more like laser production.

surfcorr Album Release

Cardboard surfboard core patterns, turned into music.

Music as a way to distribute surfboard core patterns.

Music of an unexpected character - mostly automatically
generated - surprisingly musical for being just a bunch of
cut patterns. Surprisingly dark - not a day at the beach.
Would have made it kitchy upbeat Dick Dale immitation,
if I actually knew how to make music. But the parts
had something else to express. Whatever parts! As long
as the CAD files can ride along.

In addition to other models that have been available before,
three new cut patterns appear on this album:

Simmler - me-too mini Simmons

Hot Curl - Vee from the 40's

Nuuhiwi Noserider - You know what I mean - but one of the secrets to noseriding is revealed in the name as I've spelled it.

I actually like the music, though. The link:

http://quarter-isogrid.bandcamp.com/album/surfcorr

The NAWP

Just added this core kit offer to the website. It's supposed to be like a Weber Performer. Other than the basic specs - 9'6", 24" wide, 3" thick - I took my measurements by eye, down at the Surfing Heritage Museum in San Clemente. I called ahead to see if I could bring a tape measure, realizing that might be presumptuous. It was. They said no.

You don't need a tape measure, or a CNC board scanner, to grasp the dimensions though. What I really needed to see was the rail profile transitions, how much belly the board had and where, how much dome on the deck, and like that - all things the eye and hand are pretty good at taking in.

There was a real Performer reproduction done by the Weber clan at Sacred Craft in 2010. They used one of the original, but later model templates, and the tail was way wider than most of the Performer models I've seen. I complained that if they're going to move the target like that, I'll never be able to pull off an exact copy. No sympathy. The only way my version tops theirs in authenticity is that I haven't added a leash plug. That's the best I can do.

So, the NAWP is not a Weber Performer. But if you want a Performer made out of cardboard, this is as close as you're going to get.

Part Layout Hand Edit

Also added this video to the candy aisle of the website.

Video description:

It's 550 edits to the part layout for an 8-foot cardboard surfboard core kit.

My bin packing code does an okay job of laying out parts in panels, but it's not as smart as I'd like, yet. So I made this system (that lives in a web browser) to do the final part layout optimization by hand. The game is to reduce the number of panels required as much as possible, and to reduce the distance between where a cut ends on one part and begins on the next.

"Bin packing" is the process of fitting a bunch of things in a container, or a bunch of containers, efficiently. The things might be all different sizes. The containers might even be different sizes - though in my case, I've standardized on roughly 2 foot by 1 foot panels.

The bin packing problem applies to packing lots of surfboards, gear, and people into a limited number of cars and boats, fitting files onto backup CDs, organizing your closet, and, for me, arranging parts efficiently into panels, with a minimum of wasted space, so I can cut down on materials and laser cutting time for core kit production.

You and I are fairly good at bin packing, but it's not simple to translate that skill into a computer program. My system does a decent job of laying out parts for my CNC router. But for the laser-cut core kits, the arrangement needs to be as tight as I can get it. That means editing the part layouts by hand.

The video presents a complete editing session that took me a little more than an hour. Some of my edits are pretty simple things that I'm currently adding to my bin packing program. Other edits are rearrangements that seem simple and obvious to us, but that PhD students struggle to convert into general purpose algorithms.

I haven't yet found any really-free two-dimensional bin packing software. The people who need this kind of thing are usually businesses, so the people who develop good bin packing software have a chance to be rewarded for that effort.

The initial reward though is in developing a good solution. This problem can be an addictive puzzle, and I don't think you can work on it without being caught up in the game. Beyond the merely adequate solution I'm after, my reward will be in cutting these layout review and edit sessions down from an hour plus, to something more like ten minutes.