Steam bending ribs
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TreelineIII
- Posts: 52
- Joined: Thu Mar 30, 2006 6:45 am
Steam bending ribs
I have jsut made my first attempt at bending ribs. I need to replace 4 maybe 6 ribs in the stern. I soaked the white oak for about two days prior. Then I steamed for about an hour and 20. Then I attempted to bend them around a jig I cut to the shape needed. Need I say I cracked each one. Any good secrets anybody want to give up? I attempted at first uning clams every few inches as the bend was being applied. After this did not work I then went to using a strap laying on top of the wood and then around the ends of which I then pulled tight. This created even pressure but it still cracked at the tight bend portion. I am starting to think I should bend 1/4 thick pieces and then laminate them to build up to the correct thickness. I would appreciate any help.
steaming ribs
I just went through the same thing and had the same trouble. I found that the key was making sure the whole bend is a curve. At first the way I was doing it resulted in a right angle bend. I bent mine in the boat with the bottom off. I placed multiple bridging pieces of wood about 1 inch wide along the curve of the adjacent remaining ribs. The bridging pieces were on the inside. I then bent the new ribs over the bridging pieces. Also make you are getting your steam box up to about 210 degrees before you put your ribs in. I found that I had about 2 minutes to get them bent.
Jim
Jim
Has the wood been kiln-dried? Or is it air dried? Or is it freshly cut? If dried, you should soak it for a couple of weeks. Add some salt to the water - this apparently helps (and makes it taste good too!).
Laminating is an option. Eposy does not work well with white oak. Use resorcinol and pay very close attention to the glung instructions. If using resorcinol, white oak should actually be glued at elevated tempereatures -150 degree glue line for six hours per US Navy specifications. The wood should be less that 19% moisture content.
Andreas
Laminating is an option. Eposy does not work well with white oak. Use resorcinol and pay very close attention to the glung instructions. If using resorcinol, white oak should actually be glued at elevated tempereatures -150 degree glue line for six hours per US Navy specifications. The wood should be less that 19% moisture content.
Andreas
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Rodney Syverson
- Posts: 43
- Joined: Tue Dec 27, 2005 4:52 pm
- Location: Ada, Minnesota
Treeline;
I vacillated for several months on how to bend the ribs in my Sea Lancer as I had decided to replace all of them. I built a jig and made a strap for bending the ribs out of the boat. Problem is every rib has a different curve so one jig will not work for all. Another method I thought I would try would be to bend them in the boat using the hull as a guide.
Attempt # 1, I soaked 12 white oak frames (that had been air dried), for about 2 days in the lake. I steamed about an hour. The rear 12 old frames were removed. I removed the first frame from the steam box and installed on my strap and proceded to bend around the jig. That frame broke. The next one I got in the boat and as my son handed me the frame hot out of the box I quickly began bending over my knee. I then placed it in its hull location and forced the bottom down into the keelson at the same time applying pressure with my foot and or knee forcing the frame into the curve of the hull. Then quickly pounded on the 6" tail above the hull with a heavy mallet forcing the frame tight up to the sides of the hull until it seated satisfactorily. At that point it was secured through the original screwholes with temporary smaller screws than original. Of the 12 frames we bent in the initial go we salvaged only 4. However this was the tightest bend on the hull and I could tell real fast that it is critical to have as straight grained knot free (in the area of the bend) wood as possible.
Attempt # 2 Same procedure; abandoned the jig, and intstalled directly in the boat. Six out of twelve survived.
Attempt # 3 Same procedure. As the curve softens the succes rate climbs and on the final 14 frames to install we started with 15 boards and broke only one.
You can do this and it really is quite easy and lot less work than laminating in my estimation. You need to use seasoned wood, not kiln dried, not green white oak. It needs to have a grain slope no greater than 7%. They do not necessarily have to have the grain laying in a pattern as if they were laminated in place and if you look at your original Ribs you will see the grain in the ribs does not always run parallel to the sides of the hull.
Keep trying and you will get it to work.
Good Luck
Rod
I vacillated for several months on how to bend the ribs in my Sea Lancer as I had decided to replace all of them. I built a jig and made a strap for bending the ribs out of the boat. Problem is every rib has a different curve so one jig will not work for all. Another method I thought I would try would be to bend them in the boat using the hull as a guide.
Attempt # 1, I soaked 12 white oak frames (that had been air dried), for about 2 days in the lake. I steamed about an hour. The rear 12 old frames were removed. I removed the first frame from the steam box and installed on my strap and proceded to bend around the jig. That frame broke. The next one I got in the boat and as my son handed me the frame hot out of the box I quickly began bending over my knee. I then placed it in its hull location and forced the bottom down into the keelson at the same time applying pressure with my foot and or knee forcing the frame into the curve of the hull. Then quickly pounded on the 6" tail above the hull with a heavy mallet forcing the frame tight up to the sides of the hull until it seated satisfactorily. At that point it was secured through the original screwholes with temporary smaller screws than original. Of the 12 frames we bent in the initial go we salvaged only 4. However this was the tightest bend on the hull and I could tell real fast that it is critical to have as straight grained knot free (in the area of the bend) wood as possible.
Attempt # 2 Same procedure; abandoned the jig, and intstalled directly in the boat. Six out of twelve survived.
Attempt # 3 Same procedure. As the curve softens the succes rate climbs and on the final 14 frames to install we started with 15 boards and broke only one.
You can do this and it really is quite easy and lot less work than laminating in my estimation. You need to use seasoned wood, not kiln dried, not green white oak. It needs to have a grain slope no greater than 7%. They do not necessarily have to have the grain laying in a pattern as if they were laminated in place and if you look at your original Ribs you will see the grain in the ribs does not always run parallel to the sides of the hull.
Keep trying and you will get it to work.
Good Luck
Rod