I purchased a steam bending kit from Rockler and it arrived this weekend. I have a piece that I want to bend up for the Sitar that I am building, so I figured I would try building my own steam box.
The kit from Rockler came with the steamer, the hose, plans, and hardware.
Additionally I picked up some hose for a drain line, weather stripping, a dowel, screws, and a meat thermometer. My plan is to mount the whole thing to one of my saw horses, so the box will be tailored to fit on it.
The plans for the steam box are a little vague, but that is because you need to size it to your project. I am making mine longer than I need because I hope to use it again. You can use kiln dried solid wood, or plywood. Since I have some left-over 3/4″ plywood, that is what I am going to use.
I cut a couple of boards to 3′ in length, then ripped two boards, 6″ wide and two others, 3″ wide.
I laid out centers for 3/4″ holes every 4″. I drilled them about 1/4″ deep.
I cut some 3/4″ dowels to 3-1/2″ long, and inserted them into the holes. They will support the wood strips, that I intend to steam.
When everything was lined up, I added the top and bottom and clamped it all tightly together, then inserted screws every 6″ or so.
After the sides were screwed together, I cut two end caps.
I attached weather stripping to the door side. I used a closed cell EDPM strip instead of the foam type of weather stripping. I figured the foam would act like a sponge.
I screwed on the door hinges, trying to hold the door tightly closed. I then flipped the box and attached the latch to the other side of the door.
I drilled a hole in the top for the thermometer, and one in the bottom of the door, for a steam vent.
I drilled a 1/2″ hole in the bottom at the opposite end for my drain hose. I also drilled one in the center of the rear end cap.
I attached the supplied coupling to the panel, then screwed on the panel.
I laid out two legs on a scrap piece of wood. I made the front leg 1″ taller than the rear.
I cut a 5-1/2″ wide notch in the bottom of each leg, to straddle the 2″x6″ on top of the saw horse.
To mount the legs, I made a top plate out of some scrap oak and pre-drilled the mounting holes. I then attached them to the legs.
I attached the legs to the bottom of the box, placing the taller of the two near the door end so the condensation will drain to the back end where the drain hole is.
I added a scrap piece of pine to the other side of the saw horse to support a sheet of plywood. I placed the steamer on the plywood and the steam box above, as well as a bucket for drainage.
With the box assembled, I cut the strip of walnut that I want to bend up.
The sitar has a bent aluminum bar that acts as a leg rest. I used this piece to lay out the new one.
I traced the old part, then cut it out on my band saw.
Once sanded, it looked pretty good. I did not drill the holes first because I didn’t want to introduce any additional weak spots for bending. They can be drilled later.
I fired up the steam box while I was making the crook piece. By the time that I was ready to load it in the box, It was steaming really well. the temperature in the box was around 160 degrees.
I left that to cook a while and went back into the shop to make the bending form. I laid out an arc that had a smaller radius than the original crook. I understand that you have to over-bend when steaming the wood because it will bounce back a bit when it is pulled from the form.
I screwed two pieces of plywood together to get a thick enough form, then cut it out on the band saw.
I screwed this piece to a scrap plate and went to get my strip of wood.
It steamed for about an hour, but when I tried to clamp it to the form, it started cracking almost immediately. This means that it didn’t cook for long enough.
I decided to make two more pieces and steam them for twice as long. That way, if I screw up again, I can just throw the other one back in and keep cooking it.
Two hours later, I tried again with much more success.
I decided to clamp both of the pieces to the form since I made two. Also, the second piece will have a slightly larger radius, in case I miscalculated the spring-back.
Since I have the wood stove going, I placed the form on the hearth. I will leave it there for a day or so to make sure it dries out thoroughly.
My steam box seems to have swollen and delaminated a fair bit. The weather stripping shrunk up more than I expected as well. I suspect that I will build the next one out of solid wood to try to avoid this and maybe be able to re-use it again.