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#1
12-13-2010, 10:05 AM
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Wood bending temps
Does anyone have a source that might tell what temps are best for bending different woods? What woods bend better with how much water?
I have a set of figured bubinga that I want to bend sometime soon. Trying to find out what the best temp for it is. Seems I also read somewhere here, or got it from someone, that bubinga doesn't take much water. Is there advice out there on this? Thanks in advance for any and all help, Bob 
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#3
12-13-2010, 12:52 PM
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I find that most woods require very little water - just a fine mist spray on both sides will do. Bubinga is easy to bend, unless it is highly figured. If it is highly figured, use Super Soft along with fasting and prayer. 
__________________
“Reason is itself a matter of faith. It is an act of faith to assert that our thoughts have any relation to reality at all.” ― G.K. Chesterton
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#4
12-13-2010, 01:46 PM
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Dang, I knew that Fasting thing would come up. lol.
Steve Kinnaird said about the same thing on figured bubinga. I always seem to pick out either the hardest or most expensive thing to do. It's a knack, what can I say.
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#5
12-13-2010, 02:34 PM
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just got into wood bending myself and here's a couple of my observations:
walnut= 290 to 300F wenge= 365 to 375F zebrawood= 340 to 350F cherry= 340 to 350F bubinga=320 to 330F - wood thickness varied from .125 (walnut, cherry, bubinga) to .090 (zebra, wenge). our initial instruments are gonna be small (3/4) guitars and the upper bout radius is an issue. i found that i needed to thin the wood down to about .090/.095 in order to make the bend in that area without cracking. soon as i get some q-sawn mahogany and replace the cracked upper bridge in my bender, in it goes for a test run. -don't take these numbers as gospel though -you'll need to experiment for yourself and i'm not an expert. i'd suggest watching John Hall bend wood on you tube. one key point is to get it done at a reasonably brisk pace. don't waste time but don't rush it either. the longer the wood sits without being bent the harder it'll be. get it up to temp and bend. -another problem i had was with the slats. the stainless steel ones i bought from lmi are too thick and ornrey for me. they don't really return to basic flatness without a fight and have developed kinks and flat spots that take a while to iron out. do-able, but there is an easier way and that is spring steel slats. i'm gonna order some from J. Hall asap and use them. i think i'll have a much better chance at them returning to straightness. it could also be that with smaller guitars the bout and waist radii are sharper. i haven't done a dreadnought yet. -as far as water goes i found that a light misting generally is all that's needed- like about the amount that you would spray in a mirror to clean it up were it windex. remember to use d.i. water. -at first i wrapped the sides in aluminum foil to retain water but discovered that the foil that i was using was coated in oil. thus it burned and stank and mixed in with the moisture and made runny stains. also on the walnut, the wrinkles from the foil embedded into the wood and required sanding out. i ditched the foil and now the stack is form, slat, wood, slat, blanket. -i've found that at least for me i like to lock up the waist first, then the lower bout, then the upper bout. i tried the other method of doing the bouts first then the waist, but that just seemed to pull the wood out of the bender into the bout that was being worked on. so at this time i'm not gonna do it that way. for me it's waist first to lock in the wood, then the bouts. sorry for the big rambling post but i hope it helps a little
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#6
12-13-2010, 04:49 PM
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One things that's just as important as temperature is the thickness of the wood...............or not actually the thickness, but the stiffness. As you're thinning the sides you can flex them, and feel when they start getting easier to bend. The thickness where this loosness happens can be anywhere from .100" to .070"or so.
Dont' wrap the sides in foil. I have my spring steel slats wrapped with foil. I suppose if you're using stainless steel slats no foil is necessary. Most woods don't take alot of water. Don't just crush the waist with the big press screw, and push the ends down. You can feel when it's "ready" to bend. Here's a video of me binding a Koa side. It's shot in real time, from start to finish. It isn't meant to be a "how to", but just to show how I bend sides. http://www.youtube.com/watch?v=CHxTUiErChA
__________________
woody b politically incorrect since 1964
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#7
12-13-2010, 06:13 PM
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Thanks everyone.
I intended to contact John about buying one from him. I post a lot in the KGF and have bought from him before. Woody, I watched your video. I've seen different ways of layering the wood to bend, and am interested in why you have the blanket on top. Is there anything in the blanket that could rupture or break when sliding the clamps over the two bouts? How close to bottom do you get when you initially lower the waist? Your and other demonstrations seems to go pretty quick with the wood once it gets heated. I like that idea, as Arie said, get it in, get it hot, and get it done. Also, I like the idea of spraying the paper with water instead of the wood. Steve Kinnaird said that the figured bubinga tends to facet when bent. And another friend of mine said to use some Super Soft II. Do you all think this might help in both the bending and prevention of faceting? I posted on KGF about the new LMI bender. The one thing I liked about it was the apparently precise control of temperature that their controller offers. I couldn't tell about yours Woody, and I'll sure ask John how his works regarding that. I'm betting beforehand that I could set it to max, measure temp. Set it to 3/4 and measure again, etc., to find good temp ranges. Make sense? Anyone have a good technique for that? Also, as Arie said, I won't quote those temps as exact. I'm sure it's more a temp range because each piece of wood is going to be different from another. Here's a pic of the bubinga sides and back.  Just to get an idea of the figure that's in it. I can't wait to get on it. Don't tell him, but I'm trying to model this after one that Steve Kinnaird built and let me play. Thanks all, Bob
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#8
12-13-2010, 06:40 PM
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Just in case you thought you got of easy and are feeling guilty - it sands like concrete, maybe a bit harder than sanding concrete. Think concrete with lots of gravel added. Save your prayer and fasting for that! Just so you know - this is figured bubinga   
__________________
“Reason is itself a matter of faith. It is an act of faith to assert that our thoughts have any relation to reality at all.” ― G.K. Chesterton
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#10
12-13-2010, 06:59 PM
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Gulp!!!!!!
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#11
12-13-2010, 07:02 PM
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John Mayes wrote this guide to bending and finishing. It's proven pretty reliable.
Thanks John! http://www.lint.org/TechNotes/Mayes/MayesNotes.html
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#12
12-13-2010, 07:05 PM
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I've got a router speed controller for temperature, but lately I just unplug the blanket when it gets hot enough, and plug it back in when it cools a little. Precise temperature control isn't worth much, since there's no precise temperature to bend at. When I start bending the waist I bend it all the way. With the big press screws on most benders (including my home made one) it's really easy to crush the waist. It doesn't take much pressure at all. I've always bent with the blanket on the outside. They're pretty tough. I figure with it on the inside the form could act like a big heat sink, taking heat away from the wood. I believe the most damaging thing to a blanket would be having it in the open, with nothing to heat. That's why I have the spring clamps at the ends. The keeps the blanket in contact with the slats at all times. Some builders use 2 blankets, one on top, and one underneath. I bent the sides on my first 10 on a hot pipe, but it's easier and quicker with a bending machine and blanket. I haven't bent Bubinga, so I can't help you specifically with it. Nice guitar Steve, with a nice tight bend at the cutaway.
__________________
woody b politically incorrect since 1964
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#13
12-14-2010, 12:11 AM
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Quote:
__________________
“Reason is itself a matter of faith. It is an act of faith to assert that our thoughts have any relation to reality at all.” ― G.K. Chesterton
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#14
04-06-2011, 04:36 PM
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be careful to anyone trying to bend bubinga. I'm building a guitar with it now and it's so **** stiff. I tried bending it with a jig like the one in the link. It didn't work. I just ordered a heat blanket. Thats probably the only thing thats going to be able to do it
http://www.lint.org/TechNotes/lowcostbender.html
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#15
04-06-2011, 04:37 PM
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be careful to anyone trying to bend bubinga. I'm building a guitar with it now and it's so **** stiff. I tried bending it with a jig like the one in the link. It didn't work. I just ordered a heat blanket. Thats probably the only thing thats going to be able to do it. My jig is designed like this one but has springs and additional clamping pieces. The springs aren't strong enough, you WILL need to have a bolt and nut system.
http://www.lint.org/TechNotes/lowcostbender.html
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