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| Bending figured mahogany--how? http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=12309 |
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| Author: | John Elshaw [ Sun Jun 03, 2007 6:12 am ] |
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Well, after bending many, many sets of sides (mostly rosewood and maple), I finally cracked a side beyond repair. It was a killer set of figured mahogany that seemed to be progressing fine, then before I know it, I look underneath my sidebender and see the side cracked and unrepairable. What's the trick to bending figured mahogany? It snuck up on me and cracked so fast I never realized it until it was too late. Any pointers with mahogany would be greatly appreciated. Also, since I don't think I can get a matched side, do you guys think it would look ok to use plain mahogany sides with a figured back? The back is way too awesome to just scrap. Thanks! John |
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| Author: | Shawn [ Sun Jun 03, 2007 6:39 am ] |
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Bummer...why is it that the nicest, most zoot sides that crack...I feel your pain. Because I build only classicals I have had BRW that would crack if you looked at it wrong...it is just the nature of the beast. How thick was the mahogany? Understand that with figured mahogany you do not have the long grain to help keep the side from cracking at the same thickness and temperature as had worked on non-figured mahogany. When I have grain that is highly figured or woods that are otherwise harder to bend I still bend them by hand over a pipe as at least for me it gives me immediate feedback as to how much stress the wood can take. When I have bent figured mahogany, I have only slightly misted the sides with distilled water so it is basrely wet and then use a wet scrap of veneer between the sode and the pipe to keep the side from burning. I understand that the result with not be as even and consistent as sides bent in a fox style bender but it is a tradeoff between cracking a side and consistency. As far as using plain mahogany with a figured back one option is to use a sunburst finish so that the sides will not show up as much and the attention will be drawn to the figure in the back... that is if the guitar is a steel string. One last thing...when you say that the side is unrepairable...if you force the crack together cleanly an option is to laminate the inside of that side with plain or matching veneer which will both strengthen the side as well as hold that section together. It is possible that if you used a toned finish that the section would be less visible...all of this depends on whether the side is the bass side that will be facing up or the trable side that will be on someones knee. If you can get a close match for that side then that would be the first option with all of the others above as work arounds... Good Luck, Shawn |
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| Author: | Mike Collins [ Sun Jun 03, 2007 7:06 am ] |
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Shawn has great advise. How thick were the sides?? What was the temp. of the bender? Was there runout in the wood ?? These 3 things are the most important factors in bending any sides! I've only lost one side in 30 years ! Because of short grain-runout! Mike 
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| Author: | John Elshaw [ Sun Jun 03, 2007 11:59 am ] |
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[QUOTE=Mike Collins] Shawn has great advise. How thick were the sides?? What was the temp. of the bender? Was there runout in the wood ?? These 3 things are the most important factors in bending any sides! I've only lost one side in 30 years ! Because of short grain-runout! Mike
[/QUOTE] The sides were .086" and there was no runout. This was an outstanding set from the Zootman so the wood was very high quality. As far as temp, I don't have a thermostat but the wood wasn't even close to burning. Maybe I didn't get it hot enough compared to EIRW? This was the first set I've ever cracked so I'm stumped as I followed my normal procedure. How hot should figured mahogany be to bend? Thanks for the advice fellas! John |
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| Author: | Michael Dale Payne [ Mon Jun 04, 2007 1:59 am ] |
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Maybe I missed it but was the figure curly or quilt? If so the grain can change as much as 90 deg in orientation sin fractions of an inch This causes built in stress risers. The Typical problem with thee figures is faceting and grain separation. in the waist, upper bout and cutaways bends. There is a wood softener on the market that helps. But I have never used it. I thin the upper bouts and cutaways on trouble wood to .075-.080 and make sure my sandwich keeps the blanket firmly against the wood during pre-bend heating |
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| Author: | tippie53 [ Tue Jun 05, 2007 8:29 am ] |
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When bending highly figured woods the risk is always a bit higher. I have used this technique from Bob Gleason for the past 2 years and have not lost a set since. I lightly spray the wood with water but I use kraft paper that is soaked in water and saturated. This allows more heat time without case hardening the wood. The one draw back is that you need a longer dry time. I can get a set out of the bender in less than an hour dry and ready for the mold. The added water keeps the wood from scorching and lets the fibers soften to the extent you can bend with less cracking risks. I also use a side thickness of .075 to .080 same as martin john hall blues creek guitars |
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| Author: | JJ Donohue [ Tue Jun 05, 2007 8:55 am ] |
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Super-Soft 2 grain relaxer. Check it out Here I've used this stuff on 4 highly figured woods so far (including Mahogany) and it really works. And it doesn't interfere with gluing or finishing. |
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| Author: | WaddyThomson [ Tue Jun 05, 2007 9:01 am ] |
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JJ, do you just spray it on one side? It is designed for relaxing veneer, and I didn't see any directions for bending. How do you use it? |
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| Author: | John Elshaw [ Tue Jun 12, 2007 8:53 am ] |
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Thanks to the Zootman who saw this post and graciously helped me out by finding another side set that is a perfect match with the original back. That's one more great reason to support our sponsors. I didn't even think of asking Bob, but he e-mailed me offering to help out. I thought I was hosed but now I'm back on track and will take all the advice from this thread before I bend next time. As a side note, those of you who haven't seen Bob's stash of mahogany are really missing out. I was lucky enough to get one more set before they sold out. You may want to keep an eye on his website for future reference. This is my first time building with mahogany, but as a player it's one of my favorites, especially when matched up with a great cedar top. Thanks again for all the help in this thread! John 
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| Author: | WalterK [ Tue Jun 12, 2007 4:22 pm ] |
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Hi Mr C, John Elshaw posted this picture on the OLF forum. It's a picture of a highly figured Mahogany. He mentioned that he obtained a couple of sets from you...Do you have anything similar...? I always mis out on the really exotin stuff. |
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| Author: | peterm [ Tue Jun 12, 2007 4:41 pm ] |
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John, get a digital food thermometer from K-Mart... well worth the 12 bucks! Sorry to hear about your side. |
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