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Thread: Martin OM Style Acoustic Guitar

  1. #16
    Join Date
    Jul 2012
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    Punta Gorda, FL
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    I've been working on bending the sides. I'm not a happy camper. This Stew Mac bending iron takes forever to heat up. Over an hour to get above 200 degrees!

    The first piece was too thick. That's on me. The second piece I brought down to .085". I managed to get the waist bent in about 20 minutes. Then I moved to the lower bout. Fifteen minutes of trying to get it to bend and nothing! So I checked the temp of the iron and it was between 120-130 degrees. 30 minutes ago I walked away to let the iron heat back up. I just checked it and it's at 165. This is nuts! Maybe I need the 480V version.

    I just emailed Watlow for a price on their heating blankets...
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

    Diapers and Politicians need to be changed often... Usually for the same reason.

  2. #17
    Join Date
    Jul 2012
    Location
    Punta Gorda, FL
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    2,026
    The second test piece went better


    Until I let sunlight rake across it


    So I scraped and sanded


    And shot it with some nitro


    Not too bad
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

    Diapers and Politicians need to be changed often... Usually for the same reason.

  3. #18
    Julie - that looks much better. I cannot imagine the learning curve...it must be very steep. I applaud your effort.

  4. #19
    Join Date
    Jul 2012
    Location
    Punta Gorda, FL
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    Quote Originally Posted by John Redford View Post
    Julie - that looks much better. I cannot imagine the learning curve...it must be very steep. I applaud your effort.
    Actually John, I think I made it sound worse than it really is. I spent a lot of time fretting over the rippling wood and failed to go back to the books I have to see what I may have been doing wrong. But looking back, I think the most important step is getting to know how the wood responds to heat and moisture. I've read some luthiers soak the wood in a trough. If you did that with sipo, you'd ruin it. I've found sipo to be very sensitive to moisture.

    Yesterday I bent two book-matched sides successfully and I'm ready to move forward. I referred to the Cumpiano book, Guitarmaking, and picked up a tip to spritz the wood only on the side facing the iron. On another forum, some were suggesting to spritz it on both sides and that didn't work for me.

    By the second half I developed a technique:

    1. Use a wet rag on the iron to bend the waist. The waist is the tightest bend and the only part of the bending where the good wood faces the iron so the rag both helps keep the wood wet and prevents the iron from scorching the wood. As the water evaporates, move the rag to keep steaming the wood.
    2. Spritz the inside of the piece and begin bending the upper bout. As the steaming stops, spritz again. As you progress, check the progress against a template.
    3. Repeat #2 on the lower bout.
    4. Once the piece is properly bent, put it in a form and let it sit, under pressure, overnight.

    The first half I did yesterday took me a little over an hour, mostly because I was stingy with spritzing. The second half took about 20 minutes. I didn't notice any rippling.


    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

    Diapers and Politicians need to be changed often... Usually for the same reason.

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