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| More heat helps with pesky sides http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=18713 |
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| Author: | James Orr [ Mon Sep 08, 2008 2:41 pm ] |
| Post subject: | More heat helps with pesky sides |
I've had trouble with side spring back on my most recent guitar. Following the bending procedures outlined in John Mayes' excellent article available through 13thfret.com (http://www.13thfret.com/articles.shtml) with only one blanket (John uses two), I've put the sides through four rounds of heat with a healthy dose of spring back each time. Some spring back is expected, but not so much that one should worry about cracking the side by pushing it into shape with spreaders. Yesterday I decided to do something similar to what Hesh outline in his tutorial on bending. http://luthiersforum.3element.com/forum ... l#forumTop I left the heat all the way up for three minutes or so, let it cool, and gave it another round a few hours later. The result was considerably less spring back in this pesky East Indian Rosewood, and an easy slip into the mold! |
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| Author: | Hesh [ Mon Sep 08, 2008 4:37 pm ] |
| Post subject: | Re: More heat helps with pesky sides |
Good going James my friend. I started doing the second bake for reasons of spring back too and it helps a great deal. I think that the real benefit from a re-heat is the additional heating AND cooling cycles. |
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| Author: | Michael Dale Payne [ Mon Sep 08, 2008 4:56 pm ] |
| Post subject: | Re: More heat helps with pesky sides |
These do need to be short duration cooks of 2-4 min. Much more and repeated more than a couple times I would be concerned with case hardening when allowed to cool completly then re heated. just a personal opinion I find a single 12-14 min cook of 200-220f directly after the bend is finished and then allow 12 hours in the press to produce a good set that have minimal spring back in most woods. Even with some of my early sets that sprang back a good bit, I have never cracked a set placing it in the mold. You have to have a fairly great deal of spring back in the upper bout to not have the flex needed to get a sprung out set into a mold. I am of the belief that the reason this helps is that additional small amount of residual moisture gets cooked out by the repeated cooking. I think less added moisture pre bend, 12-15 min cook at lowered temp after the bend, and prolonged time in the press is likely achieving the same thing. At least it works for me. |
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| Author: | James Orr [ Mon Sep 08, 2008 6:25 pm ] |
| Post subject: | Re: More heat helps with pesky sides |
My initial method was letting the blanket get to 305 and letting it cook for ten minutes or thereabouts. Todd, you're leaving it around 300 for half an hour? I'll need to look up case hardening. Letting the blanket go full bore didn't produce any negative effects that I can see. |
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