In my last post I left off narrating the plywood snapping even with the orientation moving parallel to the curves. I thought of a few solutions.
Increase the radius of the top curve. This is probably the most likely to succeed but will increase the overall height of the table and the curves will be not as nice as I had intended.
Attempt to make the wood more flexible through other methods such as steam or heat. This has potential to succeed and would keep the design integrity.
Try to do multiple pieces at the same time. The weakness of one piece might be counteracted by the strength of another. Of course, this runs the risk of having multiple pieces break at the same time and thereby increasing the material burn rate and project cost!
Discard the angled curve and go with a straight curve. This will succeed but I don’t like it one bit. I like the design too much to give up easily but can hold this as an option in the future.
I have decided to try option number 2. I am going to build a wood steamer using scraps and an old garment steamer I have borrowed.
Steaming wood is an age old traditional wood technique. Think about old rocking chairs that have a round back, especially shaker chairs. This is how it has been done for a long time. It is very simple, all natural, and does not cause the wood any harm or damage. You can also use straight heat but it carries more risk for scorching the wood. Some people use metal pipes and blowtorch to bend wood this way but I digress. All one needs to steam bend wood is a steam source and something to contain the steam so that the wood can absorb the moisture and heat which loosens up the lignin in the wood. I will build my box from some scrap plywood I have left from other projects.
I have a sheet of plywood that measures 33x 48 inches. This will let me have a 48″ long and 8″ wide box. Since it will be subject to both heat and moisture, I will assemble it with screws so that if there is wood movement, they should hold with a little give. I have a pocket hole jig so I’ll use that for the initial joining and then through screw the top to the already attached sides.
I’ve just attached one side to the base. You can see the pocket screws already holding the side on tight. I’ll do the same for the other side before attaching the top. You can also see that I have drilled holes in the base to allow for moisture to come out.
My box is now complete. The four sides are attached and the back is on. On the back there is a 1.5″ hole to allow excess steam to escape. When I am steaming, I will plug the hole with a rag to hold the steam in but in a way that won’t allow pressure to build. I also drilled a small hole to allow a food thermometer to slide into to measure the temperature inside the box. I also have to drill a steam inlet near the front on the side to allow the steam hose to enter the box. The front is where I will attach an access door to add wood to the box. I’ll use 2 strap hinges and a hook and eye set to keep it closed. I’ll also put on an old knob I have to give me something to grap even while wearing heavy heat resistant gloves.
I’ve attached the hose in through the side and started the steam generator. Everything looks good.
The temperature is holding steady at 220F. The test was successful and my construction should work. Next step will be to steam the plywood then clamp to the form to cool and hopefully maintain the shape without breaking. To be continued!