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Well damage is done and I have already ordered a new side set from Uncle Bob the Zootman. But here is my story

Doing an OLF Sj cutaway with Accacia/Koa. Using John Hall bender. The plain side went extremely well.

The cutaway side appeared to be going well but some of the fibers split and the cutaway bends were not smooth but I thought no problem. Cyano on the broken fibers, sanded out some rough spots and proceeded to the manual bending iron. Working slowly and making sure the bender temp was at 320 degrees. The it happened. side busted where the original fibers had let go. S--t.

Ordered new set but wondering if I missed something. Here are some of the perticulars:

Sides thicknessed to .085
Bending temp 305 degrees
Mist sides (light), wrapped in craft paper and misted paper. Made sandwich and bent center first, lower bout. The cutaway. Didnt hear any cracks, moved slowly and all seemed to be going very well.

My thought is next time to go a little thinner on sides (maybe at cutaway area, taking it down to .065
Maybe use supersoft and slightly higher bending temp. Thoughts?

Rich, sorry to hear that....

One thought on Supersoft... It can bleach Koa and Tasmanian Blackwood. I had it happen and I wouldn't risk it again. When I bend Koa or Acacia's I make sure I wet the wood well and even soak the paper. If the wood gets overly dry when bending too slow or without enough moisture it could scorch and crack.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Ahhhh, thanks Peter. I guess that comes from experience. With some of the other woods I have used I wet too much and they cupped so I intentionally did light mist This is my first cutaway so it is the price you pay to get that experience. I have paid for many other learning's over the past 7 or so years since I started. I think I am going to modify the cutaway also, more along the lines of what Breedlove does. I think the cutaway on the SJ is too tight for highly figured wood.

Would you suggest thinner sides for cutaway? I went to .085 and it seemed to go very well all over except the very sharp curve of the cutaway.

Also, thanks for the tip on the super soft. Will steer clear.

Rich,
.80" to .085" sounds good to me.
This this with your next side:

mist well the cutaway side. Wrap in craft paper. Mist craft paper and wrap it with wax paper to keep in the moisture. bent at about 305 to 310 degrees. Higher temps may be a problem too.
Thats how I bend non Rosewoods.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

I don't know how tight your cutaway is but, .080 and .085" are way too tight for the typical cutaway in koa. Most factories (Taylor, Breedlove, etc.) thickness the cutaway locally to .070" and some to .065" before bending. This may seem thin, but the tight bend actually makes it stronger. You want to start the thinning on the area between the waist and the horn and all the way through the recurve to the end of the side. Use veneer softener, craft paper and foil to keep the side moist, bend waist first, then lower bout the cutaway so you are sure the side is hot then bend SLOW. I mean slow. It takes me several minutes to bend just my cutaway, and yes I get grain lifting, creasing, etc.

I don't agree with wax paper , I would use foil. Wax paper can possibly leave a residue and with lacquer you don't need anything to contaminate it. You also may need a tad more heat Rich. Try taking the heat to 350-375. Check out this link http://www.youtube.com/watch?v=Q7vd9wGG4LM

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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

John, the wax paper wont contaminate the wood because its not is direct contact with it.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Bending tight cutaways at .080 to .085 its not the problem. I have bent many and several in Koa and Tasmanian.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Thanks again guys - appreciate all the feedback. Reviewing my notes and your feedback I think the problem was two fold - 1. not enough moisture and possibly combined with me going to fast with the cutaway - I thought I was moving slowly but now realize I should have takrn smaller bites with the crank and press. I think on the thickness I will being it closer to .08 instead of .085 and pay more attention to the thickness at the cutaway area - check for even slight variation.

Then the wrapping procedure to keep the mooisture in the wood with foil and/or wax paper makes alot of sense.

Bob C - if you are following this post - hoping my email reached you and you are putting together another set of sides for me soon.

Thanks again all.

Its funny how people do thinks differently. I was at Tony Ferguson's last year and saw a set of Indian that he had bent in to a soft cutaway, I swear they were over .1 thick! I asked him HOW do you do that! He soaks in water for a good long time and then moves to the bender. Guess its how Del Langejans does it.
I tend to lean toward Davids method of thinning to .065 to .070.

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Lance@LuthiersForum.com

I agree with the different techniques. There are certainly different roads to the same destination.

I'm not one to build cutaways or use a pipe, so I went the cheap route on my first one - I mounted a 1" galvanized pipe and layed the blanket over it. Not sure of the temp, I just plugged it in and went to town. Sprayed the sides with water, no foil or covering. Oh, I kept the sides the same at about .085, and they're about 3" across. Bottom line, I treated it like any other wood - Milo is MUCH harder to bend, IMO.

Rich, sorry about the crack. I was in your position earlier in the year when I cracked a flamed maple side for an OLF SJ, and I wasn't doing a cutaway! I successfully bent a new set along with wooden bindings and purflings, but the process did put the fear in me. I had these hopes of doing a cutaway, which sort of evaporated when I cracked the supposedly 'easy' side.

My mistake was taking too much time. I can't imagine taking several minutes to bend just the cutaway. That would require a fair amount more moisture than I was introducing to the wood.

Hopefully the new rim bends perfectly!

Ken

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http://www.casperguitar.com

Well my first successful cutaway bend !!! I got another set of sides from Uncle Bob the zootman who came through as always and got a new set of sides shipped quickly - thanks Bob - good job matching them up from memory.

Thanks to all of you who responded with advice. I followed a little of each suggestion. Went just a hair thinner and thicknessed to around .075. Discovered the broken set was actual around .083. Also followed advise of more wetting vs light spritz as I have in the past. Good wet spritz on both sides of the side and then also heavy spritz on the craft paper. Also went slower on the cutaway pressure and ran the heat up to around 310 and then let cool down to around 100 and ran it back up to 310 to set the side and try to avoid spring back. I had to touch up the very end of the cutaway on a heating pipe manually and didnt remove from the jig for around 4 hours.

I almost hate to claim success because I just finished and hope I dont jimx myself and wake up tomorrow to find they sprung back. Clamped them into the form so I think I will be alright. Might have to do some fine tuning with manal pipe after I cut to final size.

Thanks again guys - you all rock!!!

Glad to hear!

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

I'm no expert but I have struggled with cutawys until I figured out that the wood was getting to hot for to long before I started the cutaway.

Now I make a sandwich, from the top: slat, paper, side, paper, blanket and slat. I set it in the bender put a little pressure on the waist then I clamp the blanket and the bottom slat down, away from the wood, just at the upper bout. I turn the blanket on and when sizzling starts I bend it into the waist and do the lower bout. then I raise the slat and blanket back into contact with the upper bout and start that bend. Just to keep the wast and lower bout from getting to hot I spray a little water on them as I'm doing the cutaway.

Anyway, it works for me.

Joe

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Joe Beaver
Maker of Sawdust