Second Balsa Board

General Discussion
1

I have thoroughly enjoyed seeing step-by-step board building on this site. I have learned more than I ever expected from many of the generous people here. But, I still have questions. I guess those will never go away.

So, here’s my story:

A few years ago, my wife and I went to Ecuador and returned with balsa. Having never shaped a board and not wanting my first experience to ruin lots of wood I asked a local shaper, Cort Gion, if he would shape and glass a blank if I built him a blank in return. Here are some photos of that journey:

The wood

I decided the fastest and easiest method of building a balsa board was to build a solid blank, rough shape it, break it apart, chamber it, re-glue it, finish shaping and then glass it. I also wanted something that looked traditional.

I used a piece of an old board to make a rocker template. I added about one centimeter in every direction for my working template in order to make a thicker blank with some wiggle-room.

I traced the template onto the planed surfaces of planks then ran them through a band saw.

I glued the “rockered” planks together with cedar stringers then gave the blank to Cort to rough shape.

I made many mistakes on the first blank. One of which was using planks that were not straightened first. This was unavoidable because most of the wood was not straight, but I thought I could just clamp it and glue it and have the blank end up straight. This might have worked if I had used huge thick clamping blocks, but I just used small pads under each clamp. If the curved planks were symmetrical, the blank may have come out straight, but the planks were more like this: ((|() which made the center stringers very slightly curved. Curved planks caused a secondary problem of using too much glue that made breaking the rough-shaped board apart very difficult.

Here is a picture of the rough shaped board. From any angle other than straight on, the curved stringers are not noticeable.

I chambered the board using a drill press and forstner bits of different sizes to accommodate the changing thickness of the board. I now know that I could have taken out more wood, but the extra inertia is great on windy days.

Cort sealed the shaped board with a thin layer or resin before glassing.

The finished product: Not too shabby. The board rides great, like a Cadillac.

Here is a detail of the fin and tail block that I laminated.

I learned a few things from building the first blank and was able to make the second one better. I build two clamping blocks out of 2x4s that were layered to match the rocker. This made the blank dead-on straight, but I still used too much glue to keep the bent planks together. I helped Cort chamber his board. He wanted his light.

Once we finished the pair of long boards, we decided to do it again, this time our goal was a pair of short boards around 7’8”. I wanted something better for the stringers so I tracked down some reclaimed old-growth redwood that spent the last 100 years as a water tank in Yosemite. The density isn’t far off of foam and the color is unreal. Here are some fins made with redwood and balsa.

I didn’t have an old board to sacrifice for the rocker template so I scribed a template from a board that had good rocker and some thickness. I used calipers to measure the thickness of the yellow board at two-inch intervals, marked that distance below the corresponding spot on the scribed line then connected the dots with a batten for the bottom line.

I used a thickness planer and bandsaw to make the pieces that I would later glue together. Because my lumber was about 10’ long the 7’8” template fit onto straighter sections, creating straighter pieces. I also used a chalk line and bandsaw in lieu of a jointer to cut some of the more bent timbers into straight pieces. Straighter pieces means less glue which means less work when it comes time to break apart to chamber.

Here is a picture of the clamping blocks from the long boards in use with the short board project. I started gluing at the stringer and worked my way out, two pieces at a time.

The second set of blanks turned out great.

Then it was Cort’s turn.

I broke the first blank apart much easier than the previous two, although I could have used even less glue. If the pieces are straight, a drop of glue that spreads out to the size of a US quarter to 1/2 dollar spaced every 2-3 feet should be enough to hold the blank together as it is rough-shaped.

Now I have to make some decisions, and this is where I need some Swaylocks help. The long boards were made with polyester resin, and they look great, but after reading some posts on this site, I am considering epoxy. I am fairly certain that I will seal the board with epoxy, but can I then glass with poly? Does poly bond well to epoxy? Cort has been shaping and glassing for almost 40 years, but has limited experience with epoxy. Is it much more difficult? What do/did Diff, Brewer, Noll, Velzy, and some of the other great balsa folks use? What do you use?

Thanks for reading this far. I look forward to hearing any advice. I will continue to post more pictures as the journey continues.

-cmg

2

cmg, those boards look awesome.

here is a response i got from Bert regarding a similar thing to your question…

problem with poly on balsa for real board is dings and bond , the resin/glass can lift quite easily when it gets knocked …

if you say get a pressure ding , you will get this cloudy looking spot where the resin/glass has lifted making a mini delam underneath , because the wood stays dented and the resin glass spings back because its not bonded that well …

what some people do is use epoxy cheater and add a toulene epoxy thinner , it will soak into balsa , seal and go hard , when this is sanded it gives the polyester resin something to bond to , plus makes the balsa harder to dent …

i have some stuff called timber preserver used for that very purpose …

it was designed for restoring old boats where people want to keep the original timber …

this stuff soaks into the wood making it really strong …

hope that helps.

3

Thanks for the great post. That last batch of fins is just beautiful.

While I’m far from an expert on the subject, I use epoxy/poly glass combinations all the time and haven’t had an issue. I shape maybe half a dozen balsa boards per year, and my usual glass schedule is epoxy sealing coat, epoxy lamination and hot coat, poly gloss coat. In fact, it’s the same schedule that I use for my sandwich boards in various woods. If the combination stands up to the flex of a compsand, I really don’t expect any long-term problems with the stiffer balsa boards.

The only thing to keep in mind is that the bond between the two resins is purely mechanical. Thus, it’s best to have your epoxy hotcoat sufficiently roughened before glossing. I usually (or Jérôme Barbe, who glasses the rest of my boards) sand to 240 or so to get my shape exactly where I’d like, then go back and prep the surface with 120.

Otherwise, despite some initial nervousness, epoxy glassing is certainly no more difficult than polyester. It saturates the cloth a little differently, and the work times are obviously not the same, but with a bit of pre-glass reading up, there should be no issues.

Best of luck on the continuation of a terrific project. Please keep the pictures coming.

Mahalo.

4

cmg,

Great post! The boards and fins are beautiful. I’m not gonna be too much help but thanks for the info so far, I’ll remember the gluing hints. Really looking forward to the rest. What weight did the boards end up at? Have fun!

5

One of the best posts I’ve read here.

6

Fantastic

I love the chambered balsa ,thats way cool.

7

Great post…Cort has to be one of the most knowledgeable shapers around. He had quite a reputation as one of the foremost of the underground shapers when he lived on the north shore. I could never understand why he did’nt make it as big as the other more well known shapers. I was lucky enough to have him let me watch him shape a coupe of boards once. It’s nice to see him prospering up in the Pacific Northwest, spreading his aloha to the surfers there. Great pics by the way. Mahalo.

8

WOW…

Awesome! fantastic!!!

I love it! it brings me back to my origins- BALSA

you’ve done one hell of a job, thanks for the pics.

I think I’ll leave all that composite stuff aside and start playing with some wood.

9

Does poly bond well to epoxy?

Use like for like , They are two different systems . I would always use epoxy ,its better than poly and kinder.

10

What a great post ! Those boards look awesome and those old growth redwood fins are a treat. I found an old broken California redwood table in a stable and I’ve been hanging on to it for years. It has that beautiful dark timber and now I know what I’m going to do with it.

Thanks for the inspiration.

Mooneemick

I would use epoxy all the way through your current project. Much more suited to timber than poly. All the expert information on Sways I think leans in that direction. Thanks again for the post.

Mooneemick

11

Wow! Very nice.

12

Fantastic work! The second set is some of the best wooden fin work I’ve seen yet. I do have a couple of questions. First, on fin #1, is it solid wood with paint/tint around the border, or did you make a glass skeleton and use the wood as inlays? It’s difficult to tell from the picture. Also, do you chamber the “contrast strips” (I want to call them “stringers” but I’m not sure they are structurally functional in that respect) in your laminated blanks, or do you leave them solid? Thx!

-Samiam

14

Thanks for all of the replies! I will certainly use epoxy for a sealer coat, and probably throughout the project. Now, which epoxy to use? I am considering either System 3 silvertip laminating epoxy or System 3 SB-112 for the entire project, or possibly using System 3 clear coat epoxy for the sealer coat with either of the above for the rest.

Here are some answers to your questions: I have never weighed the long board, so I don’t know how heavy it is. I will try to weigh it some day. The first fin is solid. Cort made the full size blue fin in glass then cut out a hole for the wood. It looked a little small to me, so he added the red glass. As far as chambering the contrast wood (Cedar), no. It was so thin that I thought the saved weight would not be worth the trouble. Again, I wasn’t looking for a supper light long board.

The 7’8”, however, I want a little lighter, but still strong. Here is a picture of the chambers. I drill almost 1/2 way through on each side. This leaves a “micro-stringer” that helps with strength without adding much weight. Going through 1/2 way also decreases the risk of coming out the deck when drilling into a piece that tapers near the rails.

The middle three pieces are now all chambered and are glued together. I am building a “holder’ for the rail pieces so I can chamber them a bit too. The “holder” is just a piece of balsa (about 5”x5”) with a long scoop taken out that the rail should fit into so I can use the drill press without marring the wood. More pictures to follow.

-cmg

15

I remember picking up a chambered balsa shorty at a surfshop when I was young. It was lighter than a conventional board of the same size. Just stunning. It was made by Cort, I’ll never forget it. -Carl

16

Wood Orge says to seal with Zinsser Bullseye Sealcoat-lighter,one coat. Then use Resin Research Epoxy-made for surfboards UV,less toxic,easy to use.

He is the wood expert check out his balsa threads.

Nice work!

Have fun,

Ian

17

Here is a picture of the rail holders. They worked well, and I put them to use again while clamping the rails to the rest of the board, along with about 6 inner tubes.

Here are the chambered rails.

The board is now completely chambered and the glue is drying.

-cmg

18

Nice Work! As someone who has recently been through the process of building a chambered balsa board I can say I’m impressed. It’s a lot of work, but sculpting a surfboard from wood is really fun. I’m in the same position as you are right now. My board is all shaped, chambered, glued, sanded, and ready for glassing. I bought a gallon of poly laminating resin, and a gallon of sanding resin before reading about its inferiority to epoxy. I would like to just go out and buy some epoxy resin, but it is so much more expensive than the poly. I’m interested to hear how your your experience with epoxy turns out.

19
Quote:

Wood Orge says to seal with Zinsser Bullseye Sealcell-lighter,one coat. Then use Resin Research Epoxy-made for surfboards UV,less toxic,easy to use.

He is the wood expert check out his balsa threads.

Nice work!

Have fun,

Ian

If this is the thread you mean:

http://www.swaylocks.com/forum/gforum.cgi?do=post_view_flat;post=288920;page=4;sb=post_latest_reply;so=ASC;mh=25;

just to clarify, W_O had made an erroneous recommendation early in the thread naming a Zinsser product that contains wax. He corrected that in a later post to recommend “Zinsser Bulls Eye SealCoat- Universal Sanding Sealer_ 100% Wax-free Formula - Guaranteed Under ALL Clear Finishes Oil-Base and Water-Base Polyurethanes, Lacquer, Catalyzed Finishes, Epoxy and Varnish”.

Not trying to be anal - just wanted to avoid potentially misleading cmg.

-Samiam

20

Excellent post! I learned a lot!

Mahalo,

D