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| Bending Highly Figured Wood http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=1339 |
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| Author: | JJ Donohue [ Tue Mar 15, 2005 4:25 pm ] |
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I just succummed to another temptation that the Zootman pranced in my path and bought a set of waterfall Bubinga. It's just gorgeous and I look forward to getting it stickered until the day I can do it justice. With all of this highly figured stuff going around I was wondering if those who have successfully bent Bubinga as well as Eucalyptus, Sapele, etc. might share their procedure. Could you pioneers please post the conditions and techniques that were critical in successfully bending these difficult woods. Hopefully, we can focus on actual successes as opposed to theoretical possibilities. TIA |
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| Author: | Brock Poling [ Wed Mar 16, 2005 12:32 am ] |
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I have bent a set of the waterfall bubinga. I bent it on a fox bender with 2 blankets. The first trip through the bender gave me sides that were faceted on the lower bout. My heat was good, so I don't have a good answer for you about how to avoid that. To fix it I ran it through the bender a few more times, I let the heat climb to about 325 (that's as high as I dared for fear of scorching....) I used only a small amount of water and wrapped the sides in foil. This smoothed out the bulk of the facets. There were still little ridges that I could feel but I just took them off carefully at the belt sander. Everything is A-Ok now.... but I too am curious if anyone is getting a smooth bend without futzing with it. |
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| Author: | John How [ Wed Mar 16, 2005 12:45 am ] |
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I too normally use a fox style bender and after many uses started having problems with facets and even indents in the upper bout. So I replaced all of my bending forms using 3/4" dowels instead of the steel rods and I use about twice as many so they are maybe 1.5" apart. Now the forms stay together ready to use and I haven't had a problem, that is till this curly sapele bit me but that was not a problem with the form. JJ, I'd say use good heat, spritz it good with water and let it heat for a while before you clamp it down. I would not worry about going to 350 deg. I guess I should ask if you have a bender and blankets or what do you use. |
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| Author: | Brock Poling [ Wed Mar 16, 2005 12:55 am ] |
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John are you measuring your heat? I know you had a problem with one of those sapele sides cracking, but are you also saying that you had facets after bending that as well? |
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| Author: | Colby Horton [ Wed Mar 16, 2005 1:00 am ] |
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I can’t say that I have ever gotten a perfectly smooth bend with bubinga. I have only used it twice but I do have some tips for you. Keep the wood thin I recommend a range between .075-.080. Don’t use much water, just mist over the side with a spray bottle until the side looks wet. You could use a bending iron, but I don’t see why anyone would want to the fox style bender is so much easier. Also, be sure to use a lot of heat I don’t measure my temps, but I go hotter with figured bubinga than with rosewood. Be sure the side is 100% smooth on both sides. Do not have any small amounts of tear out on either side or it will swell in certain spots and be very rough. |
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| Author: | LanceK [ Wed Mar 16, 2005 1:12 am ] |
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Brock what are you using to measure your heat? My dad had a neat infrared laser deal like this LINK Its killer, but also 100 bucks! |
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| Author: | Brock Poling [ Wed Mar 16, 2005 1:52 am ] |
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Lance that is pretty cool.... I am using the $11 digital thermometers from WalMart. I use 2 of them. Colby... the only problem I see with going real thin is that if you need to smooth them out on the belt sander (I don't like to do that.... but sometimes you gotta do what you gotta do) you don't have much thickness to work with. |
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| Author: | John How [ Wed Mar 16, 2005 2:41 am ] |
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Brock, When I was having trouble I was just using the stock fox device with light bulbs. I changed everything at once. Went to the more evenly supported form and switched to a heating blanket and yes I use a surface thermometer. I usually bend at around 275? to 325/50? depending on the wood. I don't leave it hot for long but I like to get it hot while it's in there. I'll usually let it cool and then re-heat it again just to lock in the bend. |
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| Author: | John Kinnaird [ Wed Mar 16, 2005 3:03 am ] |
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I cut a test strip of that curly sapele that Bob C is selling and bent it like a pretzel over a hot bending iron. It wanted to crack on the curls until it got really hot, then it behaved itself nicely. I have no clue about the temp since I don't use a thermometer, but if you practice a few times you get a feel for the wood and then you can just feel when it gives up. Nothing like practice. Since you almost always have a little extra material on the side I recommend trimming off a little and doing some trial bends to get the feel of the wood for the temp, time, and pressure and make your mistakes there. Kindling temp is about 455 degrees so don't be afraid to crank up the heat. |
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| Author: | JJ Donohue [ Wed Mar 16, 2005 3:06 am ] |
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Thanks Brock & John...This is good info so far. Looks like it's time to buy the heating blanket. I've never heard the term "facets"...is this raised grain? If so, could it be from too much moisture? I had something similar on curly cherry recently and had to do a lot of sanding and scraping post-bending to smooth it out. BobC recommended actually spritzing the straight side to raise the grain and then sand off the high spots before bending. Could this work for Bubinga? (I know this is getting into the theoretical now) So, if I had to summarize the conditions for Bubinga so far it would be: 1) Thin sides to .080" 2) Just a spritz of water 3) Wrap in foil 4) Get it hot > 300* before bending 5) Bend slowly up to 350* OK...thanks, can we get a similar set of conditions for Eucalyptus and the Zootman's outrageous Sapele from those who have had success? I'm actually going to attach these instructions to my stickered wood so that a year from now I won't have to depend on my memory. |
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| Author: | John How [ Wed Mar 16, 2005 3:17 am ] |
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JJ, by facets I mean uneven bending in fact flats spots were there should be an even bend. |
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| Author: | Neil [ Fri Mar 18, 2005 3:09 am ] |
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I just used my Fox bender (purchased from Blues Creek Guitars several years ago) for the first time last week. I bent some mahogany and some figured walnut. It worked amazingly well. Not a hint of cracks or facets or any other problems. I assume that when everyone is talking about using the Fox bender, they are also using stainless steel or spring steel slats as well. Is this correct? I may have used too much water with my sides because they came out of the bender quite wet and had a lot of spring back. They were quite flexible, though, so I just clamped them in my work board form to dry to shape. I had read in the old LMI catalog that Martin used to bend a side every fifteen minutes using the Fox bender. They must have been doing the same thing. I also had read about using paper towels or parchment paper between the steel slates and the sides. I used paper towels since that is what I had available. Is this common practice? This might be why my sides came out so wet. |
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| Author: | Brock Poling [ Fri Mar 18, 2005 5:33 am ] |
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I think a lot of us are using foil. That keeps the water/steam contained a bit and keeps resin off of your slats. I personally find walnut one of the easiest woods to bend -- even the figured stuff. If you get it hot it is like rubber. If you are getting spring back you might cook it for a couple of cycles in the bender and let it set over night. That will usually set the bend very well. |
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| Author: | Neil [ Fri Mar 18, 2005 2:41 pm ] |
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That's good to know. I have a fondness for figured walnut. The set I bent was like rubber. Even though it sprung back out of the bender, it readily conformed to the workboard form. |
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| Author: | bob J [ Sat Mar 19, 2005 1:48 am ] |
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Re: Fox Bender. Is that the bender LMI sells? I assume that you have to build forms for each type guitar. Also, when making form, how much smaller do you make it to account for wood. Also, is the waist and ends are made even smaller for springback compensation? |
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| Author: | Mattia Valente [ Sat Mar 19, 2005 10:06 am ] |
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Bob: yes, that's it. Although I think most of use use 'Fox Style Bender' to describe any sort of contraption that bends a side to a half-guitar shaped mold, be it with light bulbs or heat blankets. With regards to size, I asked the question a while back and consensus seemed to be no comp at the weight, and some compensate the ends for springback, and some (most, maybe) don't. Make it smaller by the amount you need to; subtract the thickness of the side+whatever sandwich of material (spring steel, blanket, whatever) you've got underneath it. |
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| Author: | JJ Donohue [ Sun Mar 20, 2005 5:48 am ] |
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Can anyone post conditions they used for successfully bending the Zootman's Eucalyptus and figured Sapele sides? TIA |
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| Author: | Michael Dale Payne [ Mon Mar 21, 2005 6:59 am ] |
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Bob my molds are the outsid dims of the guitar less nominal thickness of the side wood plus one slat typicly .095". I don't compensate for spring back because it changes from wood to wood. |
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