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| side bending http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=2719 |
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| Author: | Cocephus [ Thu Aug 04, 2005 11:11 pm ] |
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I`m working the bugs out of my shop-made side bender (much like the Fox). It works very well, but I need to compensate for the spring-back that I`m sure will always happen, so I`m going to reshape my side profile patterns(OM style). Can anyone give me a ballpark idea as to how much to bring in the ends, and should I be concerned with tightening up the bend at the waist? |
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| Author: | Dickey [ Thu Aug 04, 2005 11:20 pm ] |
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Many just don't worry about it and pull it in and glue up. On my latter forms, I do compensate, based on an average springback from experience. Seems like it was about 1/2" on the lower and 3/8" on the upper. Another thing, I've found that Martin's plastic binding makes for great french curves to do that type of fairing on a large gentle curve. Good luck. I like compensating the form a bit. You can pull it either way, in or out, doesn't have to be perfect. |
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| Author: | stan thomison [ Thu Aug 04, 2005 11:40 pm ] |
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Bruce has it about right, 3/8 to 1/2" should work. I had some with no comp and you just get a little harder to make tight against the mold (in my experience about 1/8 T 1/4". Someone told me once that amount of slack/separation from side to mold OK, but it isn't, you need it tight against. You may have to play with them some to make them right for your particular mold. One thing, make sure good spreaders for you waist, and make sure rim is in level, found this helps alot also. I also started using Baltic birch end block and bolt that and head block to mold now. to keep everything level and solid through whole process in the mold |
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| Author: | Michael Dale Payne [ Fri Aug 05, 2005 2:58 am ] |
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One way to cut down on the amount of spring back is additional cooking. I bend as normal keep the side clamped in the fixture and do two or three additional 10 min cooks at about 2hour apart allowing the sides to cool in between. Leave the side clamped for 24 hrs after final cooking. Using this method I get about 1/4 max spring back on IRW a little less on some and a little more on others woods. this is with out any compensation. |
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