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I have been struggling with bending highly figured wood into cutaways without cracking the sides in the curl. So after watching the Taylor bending videos, I decided that the biggest problem is keeping the sandwhich pressed tightly against the form especially on the outside bend. I decided to incorporate some tension on the slats using swing arms and springs. This does not seem to be working as well as I had hoped. Now I know that many people bend cutaways regularly and I am wondering if maybe it was not just my technique. I had been using a simple fox style bender with a standard cutaway attachment and although I have bent them myself I am really struggling with curly wood and it is too expensive to continue my current record. Maybe someone can give me a clue or some ideas for improving my new bender. Here is a picture of the new setup.
Also I would love to see your cutaway bending setup.

John How38673.0657175926

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Thats a cool bending jig, Ive never seen one like that.
It looks like you took apart the sleeper sofa to make it.

I have trouble with the venetian bend too, thanks for bringing this up, I am looking for a better way too.

Matt

John I am totally impressed with your bender. That should do the trick!.

I personally use a hot pipe and a brass backing and just work each little area till it gives. Seems like on really tight bends there are areas that are willing to bend and there are some that are not and you can just sortof feel that when hand bending and give the harder places more time.   On the other hand, each of my venetian bends is a little different. Sometimes it becomes clear to me that a certain bend is just too severe for a particular set of sides and I compensate by making a softer bend. That;s cheating, I know.

Sometimes I thin that part of the side to about 1/16 of an inch, sometimes thinner, and then laminate that thinned section after the sides are in the mold. The laminates are made of the same wood with the grain running vertically. You would never notice it because the color is right and the laminate terminates in a side brace.

Just cheating.


If I remember correctly, John Calkin has a nice section in the GAL magazine showing what they do at Huss and Dalton. I'll try to find that and try to post those pics.
JohnJohn Kinnaird38673.3228356481

John, I've been tossing this idea around in my head for awile too. The idea I came up with is almost identical to yours (sick minds think alike). I use the standard cutaway tower on a Fox bender but was going to incorporate a tension bar like yours. My question to you is that it looks like your tension bar is fixed in that position (angled bar running to the base of the unit). Wouldn't you want it to move with the bend? My thought was to have the tension bar horizonal at first, then it would be raised (pulling upward) when the inside cutaway bend starts, and then finally end in the horizonal position. It should be pulling in the perpendicular direction to the tangent of the bend, in my mind anyway.
I'll post pics when I get it done.

Looking at your design again I must say, "never mind" regarding my last post. I think your springs have enough movement to do just what I was trying to accomplish with the movement of the tension bar.

John, I saw this one somewhere and thought it looked like it would work pretty well.

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Dave Rector
Rector Guitars

Paul, in operating my bending jig, I bwnd the waist first using the screw and then attach the the slats to the arms via the springs and bring them up to tension. Then I draw the lower bout down and secure the arm with a strap. Then I bring the upper bout down until the horn is formed. After that I secure the outer form block in place with overcenter latches and then bring the swing arm back up to horizontal and secure with the post you see in the picture. The trouble is I'm still getting crack at the horn and I'm guessing it's because of insufficient pressure. I may try some stronger springs. It's only the real strong curl that give me trouble but my cutaway bend is not that radical really.

Dave, that looks very interesting if it could be make adjustable for different shapes, and it loooks like it could.

Matt, I have a very good friend that is a metal fabrcator and since he is a musician as well, he is a willing participant. Plus he got one of my guitars for fee some time ago.

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I use a standard Fox bender with a cutaway attachment. I regularly bend
quilted maple and quilted mahogany with it. In the beginning I got a crack at
the horn just like John describes. What I finally realized is that the crack
occurred when I was trying to remove the piece from the machine and not
during the bending process. A couple of suggestions changed that. 1) let the
cutaway side stay in the machine and clamped down at least overnight-the
longer the better, and, 2) when removing from the machine, take the tension
off the back side first. Leave the center bend down. Now raise the cutaway
portion using your hand to keep the cutwaway wood in position as if it was
still being held by the press. Do NOT let it spring up! With your other hand
let the center press up far enough to get the whole side out of the machine.
I have not broken a side in about five years using this technique.

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Sylvan
http://www.wellsguitars.com

I thin my venetian cutaway sides to 1.6mm in the bend area and that seems to do the trick.

John the only "problem" I see is this: If you bend the inside part of the cutaway first, the outside, or horn, is unsupported when you bend it, thus causing a break. I would suggest you try this.
Tighten the waist, set the tension springs and then work your way outword toward the ends. Horn, then inside bend. I think you'll have better luck.

Dave--I installed the pivoting cutaway bender shown above about a year or so ago. My theory is that it gives a more tactile feel when bending similar to hand bending. The 2" diameter caul is free to rotate during the bending.
I still fracture highly figured maple occasionally but nothing like previously. I'm wondering now, after reading Sylvan's post, whether some or all of it is occuring during removal. Thanks for the heads-up, Sylvan.
I believe also that temperature/timing is very important. I use John Mayes' recommendation of 240F for starting the bend in maple and don't spend a lot of time completing the bend.
I use a digital temperature gauge with a flat leaf probe slipped in between the sandwich. I've found the cooking probe type thermometer to be unreliable as it lags the actual temperature considerably.
I've been thinking about trying to develop a bender where the wood surface opposite the caul is constantly supported even better than what the metal slats provide. This would be in the form of a segmented caul.Tacoma
The Tacoma pictures shown a steam bending process that is interesting. (Scroll down to near the bottom)
Nelson

Paul, I am working from the waist out. Waist first then lower bout then the horn and finally I bring the swing arm back up to form the inside bend of the cutaway. When all is clamped and I look between the slats everything seems fine and I don't see anything that looks like a crack. Usually you can tell before you unwrap if there is a crack so maybe Sylvan is right and I'm cracking it as I remove it. I'll try to pay a little closer attention to how I get it out of the bender.
Nelson, originally I was thinking of making a bender sort of lying flat on the table like th Tacoma pics there but after viewing the Taylor video, came up with this current design.
Thanks guys for all your suggestions

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But I hardly know you!

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Hi John
   I would be happy to call and explain what I do. I bend alot of sets in a weeks time
john hall
570-682-8046

I managed to complete this soloist style venetian bend yesterday... aside from two small tear outs which I c.a. glued shut, the side came out ok.

I was going to make this guitar a full body OM for fear of breaking my last set of this sapele, but at the last minute decided to go for it.

I bent the side free hand on the hot pipe, as I have not mastered the fox bender method yet.

I did`nt get the curves as tight as I might have with the bender, but I think I like this shape as it gives some room for my upper face brace to go all the way out the side.
I`ll most likely be a free hand guy for a while.

Matt

Here is mine - its a Blues Creek set up. I really like the waist cull that John has come up with.





And here is the result.


LanceK38675.341412037

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Lance@LuthiersForum.com

Lance,
it looks like you had good results, congrats

Likewise buddy!

I must say, id be scared to death to try and bend a cutaway into that sapele! I have 3 sets of it, and im not sure ill try a cutaway.

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Lance@LuthiersForum.com

Yes, my first try at that stuff ended up being a sharpy cutaway cuz I cracked it.

I tried making a sort of reverse call like johns caul to support the horn of the cutaway but it folded up John How38675.4547569444

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Hey John
Call me and I can tell you how to correct that problem.
jhn

here is my cut away bender. Works well although for really tight cutaways I stilluse a Pipe to touch up.

I have good luck bending sharp cutaways in figured maple by doing it in two stages. After going about half way and letting it cool, I remove the "package", disassemble and unwrap, rewet, rewrap and bend the rest of the way. Wondering if anyone has found a good way to inject more moisture into the sandwich without unwrapping it.
What about using a hypo syringe to inject water into the cutaway? If that's possible, would it be better to wait until the wood is near the boiling point on the second "go" to help disperse the moisture?
Thanks
Nelson

Nelson, I guess we all develop our own way of doing things. I am a little puzzled as to why you would heat up wood to 200 degrees +, bend half way, unwrap, moisten, re-heat and bend the rest of the way?   Wrapping moistened maple in aluminum foil as I believe you now do oughta trap moisture just fine.

Anthony--You're probably right, I've only tried it a couple times but it seems like the maple was less prone to faceting if done in two stages. My theory is that the wood has time to "relax" a little during the cooling and reheating cycle before taking the final hit. It IS a lot of extra work but willing to spend the time if it means a "perfect" bend.
Always open for suggestions.
Thanks
Nelson

With high figure, in perticular quilt I have always had issues with the tight radius of a cutaway. I have bent it first, I have bent it last I have done it in two and three stages but I seem to always have issues with figure peel or cracking. Some have advised me to not be so slow bending the turn but I crack when I try to keep the bend moving in one session. Like Nelson I have had much better luck bending a bit cooling, re-heat and bending. but I get cupping when I do this.