Benny suggested I use 1/4" balsa to do my rails with since the gluing up process is so tedious. However, I think he did his nose and tail with solid blocks.
So here I am now, stuck with not too many hours left till I go to hawaii steaming my balsa boards over my stove and two pots. And it doesn’t seem to be a fast process if it’s going to work at all.
For the first layer, the one that bonds to the foam I am going to use 5 minute epoxy. However, water might mess with that chemical process right?
What can I do to get these boards to bend without breaking and how can I bond them to the board?
Can I soak them in the hot water? Will definatley be faster but will they bond afterwards? Will I have any chance of drying them out enough afterwards in order to put the top on by Sunday night?
Hi kai. 1/4"inch strips for rails is a little bit thicker than I’m used to,but should work with the same methods I’m using. Use your rockerprofile to make your balsa strips,I’d guess 2or3 on each side depending on railshape. Then glue em up with your epoxy resin and attach them to the board with masking tape and put it in your vacuum bag and the vacuum will do the job for you. and then use tail and noseblocks where the rail didn’t stick to the curve. This is the way I do it. No water Involved.
Some guy who is into scale models building suggested to soak balsa in liquid ammonia on Shaperoom.net recently. He says it works quite good. I didn’t try it yet, though. And I suggest you wear a mask if you ever try that. Any one can back up this trick?
For a quick fix on the you can try kerfing cuts on the inside of the bends in the areas of hard bending, suggest 2mm deep cuts every 10 to 20mm. The epoxy will soak into these and bond them anyway.
hope you get it done. I dont think soaking or steaming balsa will do much good its not the right timber for that. If you do you can use a water activating PU glue to do the glue up, but be aware that balsa does suck up water and it could take a while to dryout.
Benny showed me some end grain Balsa planks today. Balsa end pieces glued together to make a board, so while weak, it is very bendable.
At the time I didn’t realize what he would really need such a thing for. Of course I’ve had these 1/4" balsa sheets for months and never took one out to see if it would bend.
Now I know why he bought them. At the moment I’ve gone to cutting the boards in half to better allow for rocker and outline. Very slow going.
At the nose and tail I think I’ll just do a nose and tail block.
A hand saw good enough to cut through the board + balsa/fiberglass to put the block in? Then you hand plane it, then hand sand it right?
If you’re sold on epoxy, sounds like nose and tail blocks are the way to go. If not, Marke’s got it with the gorilla glue and water trick. Plus there’s an easy fast way with heat to get the balsa to bend: soak it a little, then put it in place and clamp/tape in the middle of the board. Then, working towards the ends, apply heat with an iron through a wet towell. Instant steam bending. Work your way down to each end. But I like nose and tail blocks.
I really don’t have any experience with bending 1/4 balsa. But I’m going to go with 1/4 balsa rails on my next one so I’ve been thinking about it for a while. So here are some things that have gone through my head:
Ammonia ala Markyv (Softened with Ammonia from the “Understanding Bert’s technique” thread )
-where am I going to get ammonia without someone suspecting me of being a terrorist?
I have only done some experiments with 5/8 balsa to see how much the balsa absorbs water. Surprisingly, the balsa absorbs water quite fast but at a very shallow depth. I soaked my 5/8 balsa overnight in hot water and when I cut it in half the center was still dry. I read somewhere that balsa cells expand when they get wet resisting the intrusion of water.
Also, be careful with Ammonia its vapor is poisonous. HTH…
Wood_Ogre Here! Go back and read the Wood_Ogre posts. The info is there. First Balsa is not considered a good bending wood but for the bends in a surf board it is no problem. Steaming or soaking in water. Don’t bother, to messy to frustrating. 1/4 inch strips are EZ. As far as bending with Amonia forget that one too! Yes it works but it isn’t very safe and damages the wood fiber. How does it work? It changes the PH of the wood. So how can this work for you? Well slow set epoxy that is applied to all surfaces of the wood and left 5 minutes or so changes the PH of the wood. This increases the bendability of the wood by about 25%. The other thing that increases you bending is a backing strap. In the picture I used a Lexan backing strap. You can also use a couple strips of formica glued together or thin masonite. For real radical bends I use a steel backing strap with compression blocks on the ends,but we don’t need to get into that here (advanced bending). You start your bends in the center of the arc and work both dirrections with your clamping, This allows the tension to even out in the bend. How many layers can you glue at on time this way? Well I have done as many as 16 - 1/4inch strips in one setup, but that is pushing things a bit . Maybe 2 or 4 for the first couple times. Now about glue. There are APA national standards as to what can be used. But for our purpose the only one that fits is Epoxy resin glue. Not 5 minute!! Slow set or a medium set works best. The slow set allowed to soak into your wood will increase the bend that you can do. So for now look at the pictures and you get an idea of what I am talking about. Then ask more questions!
The bending backing band in the picture is clear Lexan.
clamping , start in the middle and work both ways. The clamping block are just pushed tight by hand and screwed to the work bench.
Ambrose, The bead and cove is cool but you are working with 1/4 inch stock. Although there is one company that has a 1/8inch cove bit but no bead to match. Bead and cove works OK on cedars or harder woods but dosen’t work on Balsa unless you are 1/2 or more thick. Been there! Using the bead and cove on a surfboard rail will limit how much you can shape your rails so you really have to work out your rail profiles on your frames before you start your build.Pauls method gives you more freedom to change your rail shap anytime. Aloha Wood_Ogre
Pat, I see a lot of guys here use Gorilla glue. Yes the water trick works BUT. Gorrilla glue and all his relatives are non structural glues . They are not normally used in glue lams because they creep. expand,and contract, and are affected by UV. Also heat sensetive. Failure time is supposed to be about 12 years . My Personal experience is 6 years. Use them with caution. But remember they will not hold a very sharp bend and they have no strength if they are filling a gap. I seldom use them in my shop although they do have their place. Aloha , Wood_Ogre
Hi kai. 1/4"inch strips for rails is a little bit thicker than I’m used to,but should work with the same methods I’m using. Use your rockerprofile to make your balsa strips,I’d guess 2or3 on each side depending on railshape. Then glue em up with your epoxy resin and attach them to the board with masking tape and put it in your vacuum bag and the vacuum will do the job for you. and then use tail and noseblocks where the rail didn’t stick to the curve. This is the way I do it. No water Involved.
Jimmy yoshio shibata.
Jimmy’s method seems best and easiest for a Compsand. Wood_Ogre’s way seems great for a HWB but maybe it could be adapted to Compsands. Wood_Ogre’s got a board there that does not flex, twist or compress as much as 1# EPS.
Oceanrider, Yes the Vacuum bag as shown in the picture is the way to go on a compsand. I think if you miter the tip and tape it tight and bend from the tip to the tail and leave just a hair on the tail you should be able to get that curve with !/4 inch balsa with no problem. Looks real clean. My method was intended for HWBs. For a kite surf board that is intended to go fast through heavey chop flex is not a desirable thing and a fish is short enough that you can still turn off the rails. For speed you rely on the kite power. I don’t know if the flex in the foam would be a problem with bending in my jig or not! Aloha Wood_Ogre
