I'm in the process of building a RingHawk boost glider & need to make two 5" diameter ring fins. I successfully soaked & bent some 1/16" birch plywood but compared to the equivalent size balsa ring it is quite heavy. I soaked some balsa in a mix of warm water & Windex for 1.5 hours but when I tried to get it into the bending form (a 4" PVC toilet flange) it broke across the grain. I I made a small steaming box to try steam bending.
I made the box out of 1" thick pink EPS. Cut the pieces to make a box with 4" x 4" x 32" inside dimensions. I glued it up using WEST epoxy and long sheet-rock screws to hold the pieces in place & together until the epoxy set up. I also put a piece of plywood on it & some weights overnight. When cured I drilled some small holes every 3 inches 1" above the "floor" of the box to place the steamed parts on. I then pushed bamboo chopsticks (I never throw them away after Chinese take out - too many uses for them) all the way through until there was 1/4" protruding & then used hot melt glue to hold them in place. When the glue cooled down I the did the other side and cut off the excess with a small Dozuki saw.
I then cut a piece of 3/4" piece of Baltic Birch plywood and drilled a hole in it for a 1/2" NPT fitting and siliconed it into the plywood. After the silicone set up I drilled a hole in the top of the foam box and glued it in place. I also glued an end cap and used an awl & propane torch to melt some holes for condensate & steam release.
Here's what it looks like.
Here's the aft end with the holes for excess condensate & steam.
This is the top front fitting for the steam hose.
This is the inside with the chop sticks running across from side to side.
What I did for the front cover was hot glue a 4 x 4 with tapered sides to a 6 x 6 so as I push it in the friction holds it in place. The hot glue failed the first time I used it so I made another one using epoxy.
So what am I using to make steam? An old pressure cooker. I took the valve off of the top and screwed in a barbed hose nipple, attached around 30" of hose that is attached to another one to screw into the fitting on the steam box.
Here's the steam box in action.
The first time I used it I filled the pressure cooker about 1/3rd full with water and put it on my stove without the cover on & brought the water to a boil. I then put the cover on and withing a couple of minutes I had steam coming out the aft end. The EPS foam seems to hold up quite well. I still need to make 2 good rings so it will see some more use soon.
I made the box out of 1" thick pink EPS. Cut the pieces to make a box with 4" x 4" x 32" inside dimensions. I glued it up using WEST epoxy and long sheet-rock screws to hold the pieces in place & together until the epoxy set up. I also put a piece of plywood on it & some weights overnight. When cured I drilled some small holes every 3 inches 1" above the "floor" of the box to place the steamed parts on. I then pushed bamboo chopsticks (I never throw them away after Chinese take out - too many uses for them) all the way through until there was 1/4" protruding & then used hot melt glue to hold them in place. When the glue cooled down I the did the other side and cut off the excess with a small Dozuki saw.
I then cut a piece of 3/4" piece of Baltic Birch plywood and drilled a hole in it for a 1/2" NPT fitting and siliconed it into the plywood. After the silicone set up I drilled a hole in the top of the foam box and glued it in place. I also glued an end cap and used an awl & propane torch to melt some holes for condensate & steam release.
Here's what it looks like.
Here's the aft end with the holes for excess condensate & steam.
This is the top front fitting for the steam hose.
This is the inside with the chop sticks running across from side to side.
What I did for the front cover was hot glue a 4 x 4 with tapered sides to a 6 x 6 so as I push it in the friction holds it in place. The hot glue failed the first time I used it so I made another one using epoxy.
So what am I using to make steam? An old pressure cooker. I took the valve off of the top and screwed in a barbed hose nipple, attached around 30" of hose that is attached to another one to screw into the fitting on the steam box.
Here's the steam box in action.
The first time I used it I filled the pressure cooker about 1/3rd full with water and put it on my stove without the cover on & brought the water to a boil. I then put the cover on and withing a couple of minutes I had steam coming out the aft end. The EPS foam seems to hold up quite well. I still need to make 2 good rings so it will see some more use soon.
