Soak or spray Mahogany prior to bending?

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mikeyb2

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My research has shown there are differing opinions about this. Some say soak overnight, some say soak for 10-15 minutes and some say never soak but just spray with water before bending. I'm talking about using a bending iron, not the other gizmos.
What the general consensus? Thanks Mike.
 
mikeyb2 said:
My research has shown there are differing opinions about this. Some say soak overnight, some say soak for 10-15 minutes and some say never soak but just spray with water before bending. I'm talking about using a bending iron, not the other gizmos.

What the general consensus? Thanks Mike.
Click to expand...
When I bend mahogany sides in the Foxy Bender I just spray ..
Same with the bending iron .. But when I heat bend the arched back in the Acme Bender I do it dry ..if I bend it wet, it just ripples .
 
When I use modelling grade mahogany for sides, I let it sit in a tray of boiling water for a minute or two, then into some foil before it goes into my lightbulb heated form. I might use an iron to persuade it around some of the bends too.

Max
 
Well I tried bending sides for the very first time the other day with partial success. The sides were soaked for around 30 minutes. There was a slight splitting on the inside waist(surprise!), but it has glued up reasonably well, so overall I'm pleased with my first effort. The second set was more of a disaster. They were just dipped into water and wiped down, spritzed when drying out, but were splitting everywhere and rippling. They seemed a lot more difficult to bend than the first set, which might account for the splitting, by me using too much pressure. I can't explain the rippling though.
I'm not really convinced the first set was better because of the soaking, because I did notice the woods looked different despite being from mahogany guitar sets. So before I try the 3rd set, I'd like to know which would be easier for a complete novice like me, soaking or just spraying. I would also like your opinions on the use of a bending strap, is it pretty much essential?Thanks again, Mike.
 
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I've only made about 20 instruments (all using a homemade bending iron) so I'm also a novice at this. It's definitely something that takes a little practice to master.

I have checked your posts to date and see that you have been reducing guitar tonewood sides to 2 mm. I'm wondering if you are being cautious and, despite this being your target, have left them too thick? (that makes them difficult to bend). If they really are uniformly 2 mm or less, it could be that the iron isn't hot enough, or that you are being impatient and forcing the wood rather than feeling for the point when its ready to yield.

I don't soak, I spray and then try bending. Some wood yields fairly quickly, some takes time and needs to be sprayed periodically as you patiently persevere. I don't use a strap, though that may help you. I concentrate on keeping the sides square to the iron. You definitely need to learn to feel when the wood is ready: its not about applying a lot of pressure, its about applying enough pressure when the wood tells you it's time to try. If it's not bending it's because it's not ready rather than that you are not applying enough pressure.

Good luck!
 
greenscoe said:
I've only made about 20 instruments (all using a homemade bending iron) so I'm also a novice at this. It's definitely something that takes a little practice to master.

I have checked your posts to date and see that you have been reducing guitar tonewood sides to 2 mm. I'm wondering if you are being cautious and, despite this being your target, have left them too thick? (that makes them difficult to bend). If they really are uniformly 2 mm or less, it could be that the iron isn't hot enough, or that you are being impatient and forcing the wood rather than feeling for the point when its ready to yield.

I don't soak, I spray and then try bending. Some wood yields fairly quickly, some takes time and needs to be sprayed periodically as you patiently persevere. I don't use a strap, though that may help you. I concentrate on keeping the sides square to the iron. You definitely need to learn to feel when the wood is ready: its not about applying a lot of pressure, its about applying enough pressure when the wood tells you it's time to try. If it's not bending it's because it's not ready rather than that you are not applying enough pressure.

Good luck!
Click to expand...
Thanks, I take all your points and will concede that you could be right on all counts. Although my target was, as you rightly say, 2mm I did settle on something more like 2.2mm. I am going to take the last set down to 2mm or slightly below, and see what happens. I am tempted also to buy a bending strap. Cheers Mike.
 
Mike
I am one of the few professional builders who still hand bends - I use a machine to 'set' the bends and it is this reverse method that maintains the shape; there is no spring-back!
With mahogany you need three conditions:
  • Hot iron
  • Thin sides
  • Dry bend
Like all woods there is a fine line between scorching and just right. Some mahoganies, particularly the African varieties bend well. Very light-weight mahoganies can crease and the fibres crush and no amount of soaking and steaming will get rid of the ugly lines across the grain that result form this. 2.2mm is a good side thickness for larger instruments like guitars and baritone ukes ( although some of Martin production guitars are less than this). May I suggest you get down to at least 1.8mm for instruments smaller than this so you have a good chance of getting the bend. Only use water to stop scorching. Steam is created just above 240 degrees F. Your iron should be 300 degrees plus... It seems to me that water if it is used it only softens the fibres because any steam produced does not 'help' bending. You also get reactions to the minerals in the water and if using an iron pipe this is a recipe for some frustrating after sanding of iron stain. Water is also a killer if your wood is figured and you are hand bending (answering the post question...)
As you are in the UK and it looks like you will be making more instruments invest in a Camarillo iron, Brady hybrid pattern. These are British made to order irons that are light years ahead of the Ibex model (I am on my second Ibex having burnt out the first) and cost less. You will have to wait about 5 weeks for one...
My next instruction video will be on hand bending but I need to make some surplus before I can fund another week in the studio :)

 
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Pete Howlett said:
Mike
I am one of the few professional builders who still hand bends - I use a machine to 'set' the bends and it is this reverse method that maintains the shape; there is no spring-back!
With mahogany you need three conditions:
  • Hot iron
  • Thin sides
  • Dry bend
Like all woods there is a fine line between scorching and just right. Some mahoganies, particularly the African varieties bend well. Very light-weight mahoganies can crease and the fibres crush and no amount of soaking and steaming will get rid of the ugly lines across the grain that result form this. 2.2mm is a good side thickness for larger instruments like guitars and baritone ukes ( although some of Martin production guitars are less than this). May I suggest you get down to at least 1.8mm for instruments smaller than this so you have a good chance of getting the bend. Only use water to stop scorching. Steam is created just above 240 degrees F. Your iron should be 300 degrees plus... It seems to me that water if it is used it only softens the fibres because any steam produced does not 'help' bending. You also get reactions to the minerals in the water and if using an iron pipe this is a recipe for some frustrating after sanding of iron stain. Water is also a killer if your wood is figured and you are hand bending (answering the post question...)
As you are in the UK and it looks like you will be making more instruments invest in a Camarillo iron, Brady hybrid pattern. These are British made to order irons that are light years ahead of the Ibex model (I am on my second Ibex having burnt out the first) and cost less. You will have to wait about 5 weeks for one...
My next instruction video will be on hand bending but I need to make some surplus before I can fund another week in the studio :)

Click to expand...

Thanks Pete, that's great and much appreciated. I've considered the iron you mention, although the one I've made seems ok in terms of reaching and maintaining the required temperatures. 5 weeks though makes me think of a little Christmas present, hmmm? What are your thoughts about a bending strap? Should I need one if all your other criteria are met? Mike.
 
you can soak it over night, or just sprits it. or just soak for 10-20 minutes, even just bent it dry, your main property for bending is heat source. But also the thickness of the wood type. for a beginner you can go 1.6mm for the sides. at 1.6 you can use your wifes curling iron and will work flawlessly.
 
Well I took the advice, hot iron ,dry bending after thinning down to 1.8(ish) and the bending was a little bit easier( but certainly not easy). Unfortunately, there was still rippling across the width. I experimented with some scraps, and it seems that the wood with the most visible obvious heavy grain bends more easily, but the wood I'm having the most trouble with is plainer looking. I have used a guitar set, but used the intended back wood for my sides and the intended sides have been edge joined for my top and back( hope that makes sense) The intended guitar sides are very heavily grained, and the back pieces are plainer. I'm wondering if sets are chosen that way, for a reason. Maybe I should have used them as intended. Anyway, I'll have to buy another set now, before I can try some more.
 
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Alright Pete! As we say here in America: You da man! (Translation: You are a very good person worthy of respect and/or admiration).
 
My concern is the constant mis-information presented here regarding tasks like this. Bending is science - wood is a thermo plastic and an understanding of how molecular bonds work really helps in the process of bending. Also when I was struggling with my first figured sets of koa I had great advice from Bob Gleason of Pegasus Guitars. This was in the days before the internet and YouTube and he became an 'on demand' mentor and friend, and as such, I feel I have responsibility to give back :)
 
Just like to thank Pete for showing me the dry bending process, and the advice on improving my mould. Points noted in particular were that the temperature of the iron needs to be right, and also the way the wood is presented to the different surfaces of the iron, and use of the left hand to apply the pressure and right hand to feed the wood across the iron. I hope I can put this knowledge into practice when my new iron arrives.
I also was encouraged by Pete's acknowledgement that my particular wood was challenging to bend, even though Pete was able to bend it without any problems.
Many thanks Pete.
 
You're welcome Mike - I've hand bent nearly all the sides to my instruments (over 700), guitars and ukulele and bent just about every traditional tonewood there is (I have no experience with the new central and south American rosewoods coming on the market). What I can tell you with absolute clarity is - each piece is different and there is only one rule of thumb to hand bending - get the iron at the right temperature. There is only one safety net - use a flexible backing piece (I use 0.2mm stainless shim stock) to support difficult wood. There is one caution - don't soak your wood. It simply does not need it if you have the temperature correct. I only use water if my iron is too hot and then I tend to spray it on t he iron, not the wood!

One last point - ever wondered why the longer you are on the iron, the harder it gets? This is because you are beginning to 'stiffen' the molecular bonds in the wood making it harder to weaken them with the energy provided by the heat. You need to get hotter and then the scorching begins :( You really have to confidently get to your desired shape within about 10 - 15 minutes per rib or you are going to have a fight on your hands... Like every task in luthiery, it takes time, repetition and skill to consistently achieve a successful outcome.
 
mikeyb2: Glad to hear you now see what's required to bend successfully. Words aren't nearly as helpful as a little instruction and observation of the task being done by a competent person. Its great to hear forum members like Pete are willing to help out in his way.
 
Torres did his guitar sides at around 1.5 mm's and under, some as thin as 1 mm. That's on a Side width of 80 mm's+.
Scary but certainly easier to bend. As for rippling across the width, water can make it worse. The only part of the Side that I spritz is the waist, the rest is bent dry. Some wood just wants to cup and corrugate though. I think it's related to varying hardness/density across the width. I've just bent some Yellow Cedar and it's virtually ruler flat. The wood is perfectly quarter sawn, extremely fine and extremely straight grain. That makes things easy. Yellow Cedar is soft though, so you have to watch for creasing.
 
Here is a simple device i made to prevent myself from toasting my fingers on the iron..it's a thin strip of .007" brass shim stock nailed to a block of mahogany scrap..Works great for me :D
 
Pete Howlett said:
You're welcome Mike - I've hand bent nearly all the sides to my instruments (over 700), guitars and ukulele and bent just about every traditional tonewood there is (I have no experience with the new central and south American rosewoods coming on the market). What I can tell you with absolute clarity is - each piece is different and there is only one rule of thumb to hand bending - get the iron at the right temperature. There is only one safety net - use a flexible backing piece (I use 0.2mm stainless shim stock) to support difficult wood. There is one caution - don't soak your wood. It simply does not need it if you have the temperature correct. I only use water if my iron is too hot and then I tend to spray it on t he iron, not the wood!

One last point - ever wondered why the longer you are on the iron, the harder it gets? This is because you are beginning to 'stiffen' the molecular bonds in the wood making it harder to weaken them with the energy provided by the heat. You need to get hotter and then the scorching begins :( You really have to confidently get to your desired shape within about 10 - 15 minutes per rib or you are going to have a fight on your hands... Like every task in luthiery, it takes time, repetition and skill to consistently achieve a successful outcome.
Click to expand...
I take note of your second paragraph Pete, and I did notice how long it took you to bend a side. Longer than expected, which probably means I was also rushing the process. Thanks again Pete and thanks also to everyone else for your help.
 
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