If we don't add the rails right away, the foam will flatten out. Once a band of wood is glued to the rails, the foam will hold the rocker. I added a piece of 1/4" thick wood under the nose when I did these boards and when I lay it on the rocker table it still has that extra bit of rocker.
In hindsight, this process is time consuming and a lot of work, but if you want to do veneers, vac bagging is probably the best way to do it. If you don't mind the extra weight, using thin plywood would make it a lot easier and faster. Model airplane Balsa works great, but it only comes in 4' lengths. To use the fancy woods, I really need more equipment. My brother has a thickness planer and a joiner, but trying to coordinate time to use them is a hassle. I could use a thickness sander as well because the planer tears some of the woods we used. I also need to re-calibrate my vacuum pump. The gauge is not working, and whatever it was set at is a little too strong for Home Depot foam.
Here's the board with the wood rails. I try to cut the strips as close to the width I need, but this board has so much curve my pencil couldn't get all the way in to mark the wood. I used some 1/4" thick wiliwili for the straighter tail section and balsa for the rest. You can see in some of the photos that I had to cut away quite a bit of wood. I used a razor knife and several small hand planes to work it down to match the board. I cut out a nose and a tail block for this board, and glued it on with poly glue.
Back to the blue rail board. After the nose and tail blocks were glued on, I drew outline then cut it out and went to town shaping the nose and tail blocks, then turned the rails, and sanded the big scratches out of the top and bottom. You can see the cuts I made to help the foam wrap around the nose.
Loving this thread.
Do you cut rocker into the wood strips you use for rail bands or just force the curve in?
Depends on what wood I use. I have a stash of Balsa sticks that are 1/4" x 1/4" from 18" up to 48" long, and others that go all the way down to 1/16" x 1/16" x 18". Those will bend most curves, but I have to use up to 5 strips to get a single band. With the sticks, I just tape them along the rail following the curve of the outline and rocker.
For single piece bands, we cut the rocker and use the outline to get the shape right. I've been using heavy paper or poster board and make a template of the bottom rocker. My brother makes his first band the full thickness of the blank, but I made mine about an inch and a half. There's less to cut later because the thickness of my boards at the rails are about an inch or just a bit more. We've also been using 1/8" plywood for the 1st band, but any wood would do. I think a solid wood is better because ply tears when you plane it. I made a few bands of redwood recently, and at 1/4" x 1/4" it will bend easily. For wider pieces, wet it, and it will bend, or make it thinner. At 1/8" most lighter wood bends quite a bit, but you can usually only bend it around one curve and the boards have 2 curves.
These boards are being made much more complicated than it could be. If you us a simple skin, like a full sheet of thin wood, you don't have to mess with piecing together a bunch of small pieces. You can use another board as the rocker table, if you have a board with the rocker you want to use. The trick to using another board is to keep the sheets of foam full thickness, and place the top of the foam against the bottom of the board. If you profile it, it will change the rocker, so you have the ability to use a board and make a different rocker, but you have to plan it out.
Balsa is easy to work with because it is soft, you just have to go through it and organize the pieces that bend the most to the pieces that don't bend easily. If you cut a bunch of grooves into a sheet of ply, you can get it to bend around different curves. I just think the plywood is too heavy, but it makes a solid board. Woven 4' x 8' bamboo sheets work well too, they make really strong skins, they are light, and the sheets are very flexible.
awesome build Harry.
Charlie, you taught us how to do this. We just added the Home Depot foam to the mix.
You are the master, we're still students. Thank you for all the time you spent teaching us, and all the stuff you gave us over the years.
This is rad.
love a good compsand, have to do another one soon.
here is a blast from the 2 years ago past.
Sunshine Coast (hoax) Queensland Australia
Added a Wiliwili nose block and Koa tail block on board one. Shaping is done. I need to do a seal coat then I'll glass it. I glassed board 2 and after doing that I realized I should do the seal coat first.
Glassed board 2 and it had a lot of issues with air on the second side (deck). I had to do a lot of babysitting to keep the glass from lifting. After I did the fill coat on the deck (side 2), I noticed a lot of pin holes. I sanded the deck side then I made a hole on the bottom where the fin box will go. It's just a 1/2" bit through the skin, (I didn't route the box slot). I made small vacuum patch and then I taped it over the hole and did a thin filler coat that had lots of aerosil. Check out the videos by Jimmy Lewis doing his poor man vac series, that's where I learned this.
Attached my vac pump and hope it pulls the resin in. Going to sand smooth, then do several coats of floor sealer for the finish.
I still have to add the fin box then a fill coat, sand, then final coat.