Official Luthiers Forum!

A while back I asked OLFers what YOU wanted to discuss. You came up with a great list of interesting ideas and I captured this list.

One of the things that folks asked for that would be VERY helpful to a lot of builders is a listing of everything that we need to know to successfully bend specific woods. For example if I want to bend Koa it would be great if I could just access a spread sheet either physically or as a saved file on my computer that told me bending thicknesses, temps, how much/little water, bake once, twice etc.

I was speaking with my buddy Paul Burner today and Paul graciously agreed to put all of the relevant info that results from this thread into a spread sheet and make it available for all who want a copy via download.

So folks let's collaborate to assemble info for not only the common woods but the not-so-common woods too? How you can help is to post here how you bend specific woods. Please indicate the thickness, figured or not, temps, amount of water if any, characteristics that you observed such as spring back, cracking, what ever, and anything else notable such as how Koa can turn green when in contact with metals.

Thanks

I agree with Hesh that this will be a great tool to have easy access to. When you get to be my age you need all the references you can get your hands on as the mind can't hold all those values.

(But why can I still remember my 8th grade girlfriend's phone number. Can't that data be purged to free up more space?)

Along with compiling the list - we should also discuss how you want the information organized.

Doing a quick search I came up with the following:

Brazilian Rosewood 305
Cocobolo 310
Ebony 315
Indian Rosewood 300
Koa 300
Mahogany 270
Maple (bigleaf) 290
Maple (European) 280
Myrtle 275-310
Narra 275
Paduk 375
Sapele 275
Tasmanian Blackwood 300
Walnut 300
Ziricote 315

Other Rosewoods 300

Now - I know we'll have some additional discussions with comments like this:

Mahogany: 270
Bend starting at 270 - after set to pattern take to 375° for 2 minutes then hold at 250° for 15 minutes (J. Hall)

I know in the long run it will be worth the work!

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P A U L B U R N E R
Burner Guitars

I recently bent 2 sets for L-00 and Jumbo. Following are specifics:

- Wood: African Mahogany
- Set-up: I used John Hall bending jig, and his process (see his video tutorial for specifics)
- Thickness: Right at .080
- Grain: Plain Jane, but well quartered.
- Spritzed water on each side, not alot
- Heated to 250, then started bend
- Bent waist to tension, then lower bout, then upper bout, then waist all the way - done bending in about 5 minutes.
- Took up to 375 ish for a few min
- Burned off water for 10 min or so at 225-230

I left in the bender till totally cool, then put in mold. I saw very little spring back, if any (certainly nothing to worry about).

I also bent my Mad RW bindings at the same time as the sides (2 bindings per side).

Results: No cracks, bent fine, no scorching at all. Fit perfectly in mold.

Glenn

I have a spreadsheet that estimates how sharp of a radius you can bend given a certain thickness. I can post that if you guys would be interested. I set it up to be a bit conservative...seems to work pretty well though.

Thanks,
Trev

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http://www.PeakeGuitars.com

Here's one I recently did:

Tasmanian Tiger Myrtle

Temp: 300
Water: Light spritz
Wrap: craft paper
Thickness: .080
Misc: Bent w/blanket, bend once let cool overnight and then wake-and-bake cooking it again one more time

Paul we might wanna lay out the sheet to look something like this:

Wood Type, figured or not, bending thickness, wrap, moisture, temp, duration, repeat y/n, special considerations

Anything else that anyone believes would be useful to most builders would be cool too.

Who's going to be the first kid on their block to provide the info for bending The Tree Mahogany?

It's a good idea (I guess) but we should all make it clear that the conditions we list for a specific wood are not necessarily what is needed to bend that wood, but what worked (perhaps only once) for us.
And, that we are talking only about bending with a heat blanket on a Fox-type bending machine.
Some woods are so 'forgiving' that they will bend just about whatever you do to them, others can vary a lot from piece to piece, etc.
A list of 'bending temperatures' is helpful (thought not at all clear that it is actually the wood temp being measured) but does anybody think that they can control the wood temp to within 5-10 degrees F, and that such small differences are important?
It seems to me that the table Paul posted could be simplified to "Most woods 275-300 deg F range, padauk much hotter at 375 deg F".

Though there is general agreement on some ideas about bending - most folks say that curly maple shouldn't be gotten very wet, for example - some woods can be bent just about any way you want - from boiling in a pan and clamping to a form to bending 'dry' (ie using the water/oils in the wood). I'd hate for novices to think that to bend a piece of IRW you need to get out a digital thermometer!
I've not bent many 'challenging' pieces of wood - cowardly, I guess- so this will help me in the future. Perhaps I'll even buy another thermometer to replace the one I used one time before it failed!

Cheers
John
PS/EDIT- Do you want input from people who don't measure temps? And for those who do measure temp, should the way they measure that temperature be listed?

Hesh-
Whatever that stuff is, just send me a few dozen sets and I'll be happy to report back my experiments!

Yeah - right.... But I do owe you some zoot my friend that's for sure....

John I agree that this listing will only be a rough guide no better than any thread here when someone asks for temps, thicknesses, etc. I also agree that in order to keep this simple all listings should be for using a bending machine and blanket. Variables still remain though such as blanket on top or on the bottom, third slat, etc. but hopefully folks contributing info will also let us know if they do anything out of the ordinary in their own system.

This is not rocket science and we should collectively be able to vet listings in this thread and head off using potentially unworkable info.

The goal which I agree is a worthy one and something that was specifically requested by OLFers is when complete a listing of what you need to know to bend various woods available for all and at any time. I can't tell you how many questions we receive that this spread sheet would help the requester help themselves.

Thanks again everyone.

Just a beginner here so I can't add much but I am watching this thread very carefully. Thanks guys!!

Parser, that radius info sounds useful. Charging in and experimenting is fun, but sometimes you want to increase your chances for success.
Hugh

Thinking about this a bit, it seems to me that using heating blankets and bending 'machines' - which I use, and like - does mean that you are 'flying blind' to a great extent.
It is so easy to crank down the waist when the wood may not be 'ready to bend', or to overcook the wood, etc.
That's where temp guidelines like the ones posted here can be so helpful.

I think that keeping a bending iron around and bending the occasional binding, solid lining, etc is a good way to keep your 'touch' for this sort of thing.

Cheers
John

IIRC Mario uses a bender but does the bending by gloved hand so he retains the "feel" of the wood. I like this idea a lot and wish there was a video of Mario's technique so that I could see if it would work for me too.

Randolph thanks buddy - we are hoping to put together this spread sheet for folks like you who might benefit from it.

Yes, but what about white oak?
For those of you that don't mind your git-box looking like yer granny's furniture, I bent highly figured QS white oak to a tight radius for my Larson parlor. Here's the particulars...

John hall bender, with blanket under sandwich.
Spritz with SS2, let soak in for 10 min. (was in a hurry).
Bend large bout first at about 280, then small at around 300, and waist at 320, crank 'er down slowly. Bake for 10 min. and let cool down. Had a couple of tiny cracks on the inside at the edges, but usable and covered by kerfing.
Were I to do it again, I'd probably let the SS2 go overnite or more before bending.

I think that these are excellent suggestions and yeah this is not an easy topic to even design the data base for.....

The intent is of course to have a guide available that would let folks self-serve themselves for common, repeat questions such as what temp do you bend mahogany at. It seems to me that something else that greatly complicates matters is that not everyone bends the same way. Some bake for long periods of time at reduced temps, some bake twice, etc.

Agreed this is not going to be easy but then that is part of what makes it worthwhile in my view too in as much as if we do build a decent guide that most agree is generally valid info that will be just one more unique value that the OLF provides.

I am completely open to suggestions on how to proceed and thank everyone who has already provided valuable insight.

More thoughts please?

My recent bends use the following formula .. I have the 2.5 watt blanket, thats about 550 watts, I have no temp sensor, so ... blanket on full blast for two minutes, then start bending, somewhat fast .. in about 3 minutes, its all done, turn down about 30 percent of the dial, leave for another ten minutes - we have bent padauk, EIrw, curly koa, macassar ebony, hondo and african mahogany, mad rw .. and then we also bent a set of ziricote bindings ... but forgot to plug the blanket in ... bent them cold to my signature shape (OMish) in the same 3 minutes .. then when we realized, plugged in blanket after the fact to set the bends .. no cracks at all

After Luc showed me the vidd of his English buddy with the cig in his mouth bending .. I realized I was bending too slow .. no more.

_________________
Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

The temp range for most woods is pretty wide actually. The most important thing is time and heat duration. Most woods will bend well within the ranges stated. I use 275 to 375. The only real exception is Paduk . That stuff you need as hot as you can get. I will say that water can cause some problems . Never soak and use a little as you can . At most I use a light spritz .
It isn't rocket science and the more you bend the more confidence you will have. The more figured the wood the higher the risk. I think Maple is one wood the may crack the most because of the figure and grain runout.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I bent a set of QS white oak to a 0 size at 280 degrees. Slightly spritz with water only. Let the temp build at full power to 280 with a little tension at the waist. Held the temp at 280 with router control. When the steam started and the ends started to droop, I slowly tightened the waist all the way, Then the upper boiut, followed by lower bout. Let sit in bender at 280 for 15 min., then until cool. No cracks, total time to do actual bending...about 5 min.

Chuck

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As for water, the easiest set of cocobolo I ever bent was when I soaked it in not quite boiling water for 10 minutes first. Bent real easy into a very thight cutaway and absolutely no springback, ripples, or discoloration.

Grant

I always wonder about this. I mean I've heard of some of the folks who've been at this for over 30 years soak their wood. Olson, Hoffman, Henderson, & Cumpiano (look in his book) and I know a local guitar and mandolin maker who's been at it for 34 years now, soaks his wood too. With the exception of Cumpiano (because I don't know how many guitars he's made over the years), these guys have each made over 400 guitars and Olson is around 1300 now.

So how is it that these guys all say to soak it and others say don't soak it, just a light spritz.

I'm starting to wonder if the amount of water makes much difference at all. I know and understand about cupping, but just make sure to cycle the heat a few times and if most of the moisture is gone, cupping ain't going to be an issue.

I wonder if BRW bends easier if soaked (Henderson uses alot of BRW and soaks) vs just a spritz.....?

Really though it seems like any amount of water will work.....spritz.....almost nothing.....soaking.....

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

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To add to Rod True's list-
David Russell Young in 'The Steel string Guitar; Construction and Repair':
pg32:
"Rosewood should be soaked overnight before bending. the bathtub is fine for this- but weight the sides so that they remain completely submerged.
..........
Mahogany sides can be soaked under a tap just prior to bending. Keep water and a sponge handy while working so that the wood does not get too dry and scorch."

Arthur Overholtzer in 'Classic Guitar Making':
pg77:
"All solid woods will bend and hold their shapes better if first soaked in water."

Lots of ways to get those sides bent!

Cheers
John