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Thread: Martin OM Style Acoustic Guitar

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  1. #1
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    Martin OM Style Acoustic Guitar

    Here we go...

    I'm using plans from LMI. The guitar is based on Martin's OM model.


    Two sitka spruce soundboard pairs were purchased from Alaska Specialty for $8@


    I also bought some sitka splits for the braces


    The tools I have been using so far


    Rather than making templates and forms from plans like I've done in the past, I took the lazy way out


    I milled the sitka splits on the tabla saw to the dimensions shown on the plan. To rough cut the sweep on the brace tops, I used a jewelers saw then went to planes, rasps and sandpaper to finish.
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

  2. #2
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    This is going to be fun to watch!
    --

    The most expensive tool is the one you buy "cheaply" and often...

  3. #3
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    After spraying the final coat of poly on the kitchen cabinets, I rewarded myself with some time on the guitar. The brace thing and "voicing" the soundboard is, from what I have heard and read time and again, a kind of voodoo magic combined with throwing darts and some serious engineering, all reliant on how the guitar sounds in the hands of different people. Easy peasy.

    After getting my hands "conditioned" to making braces, things started looking up


    I have absolutely no idea what kind of sound this will bring but at least the braces are shaped according to the plans.


    Before I can glue them to the soundboard I have to rout out for the rosette. For this soundboard I opted to buy some pre-made rosettes. For now, I want to concentrate on learning the fundamentals.


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

  4. #4
    Hello! I'm in the middle of building my first guitar as well. I am following Kinkead's book and using his plans (kinda). If you are following his procedures, you might want to look into the neck joint and neck angle somewhere else. I've found that Kinkead sort of glosses over those parts. Depending on what you decide and which system you follow, it might be important to address the shape of the sides near the upper bout before you glue the top on. I think this is something I wouldn't have looked at if I'd only been looking at Kinkead's book.

    I was also pretty bamboozled by shaping the braces. I made a guess just like you did. Mine was based mostly on watching a video where Dana Bourgois voices a guitar top. It's a cool video even if you feel more confused after watching it than before. Also I get the impression that the way he looks at voicing a top is only his way and others may disagree. There don't seem to be too many other free options on youtube though....


    Hope it goes well! I'll be watching with great interest.

  5. #5
    Just realized you might be the same person I responded to on OLF. If so, sorry for the flood of similar advice!

  6. #6
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    Thanks, Adam! I've kind of conceded to the fact that voicing the soundboard is as much voodoo as it is science, if for no other reason than the fact that even within the same tree, there is no reliable consistency in cell structure from one spot to another. I'm thinking there may be a lot of completed soundboards that never made it into a guitar and probably some guitars that ended up as El Kabong! guitars (see the video below). In his voicing video, Dana Bourgois used a soundboard he said was a reject yet it looked perfectly fine.

    The Gore & Gilet book sounds interesting and some say it will help understand the science sufficiently to be able to turn out a good guitar on your first attempt. The GAL videos I've seen are also pretty interesting and have, at the very least, given me a real appreciation and deep respect for those who have mastered the art.

    The rosettes have yet to arrive so the soundboard work hasn't progressed, making this a good time to cross some things off the procrastination list.


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

  7. #7
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    This is going to be fun to watch.

    The OM is a nice little guitar. All I have are Dreadnoughts and an old Brazilian Craviola. Voicing is art, not science. But it isn’t as daunting as it seems.
    Shawn

    "no trees were harmed in the creation of this message, however some electrons were temporarily inconvenienced."

    "I resent having to use my brain to do your thinking"

  8. #8
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    I don't think voicing is something to be too concerned about at first, though maybe I don't know what I'm missing. If you follow the plans and practice good joinery and have good materials you'll end up with a good sounding instrument. Voicing reportedly enables those who can do it to fine-tune the parameters of the sound they want to get, or to have more repeatable results, but it's not like an 'unvoiced' instrument won't still sound good.
    Zach

  9. #9
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    I was reading an article in American Lutherie about Olivier Fanton d'Andon, a French luthier. He said, "bracing is the most difficult part, the most fastidious part. It is long work and I have to adjust and carve each bar very slowly." As he works the bracing, he listens for harmonics. Something else he said stuck - "The purfling has to be as thin as possible: it is very important for the sound." His purflings are 3mm thick.

    Still waiting on the rosettes...
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

  10. #10
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    The rosettes finally came. I used my homemade Dremel circle jig to rout out the soundboard. It came out perfect.


    I have to make some dished bases for the top and back, at 15' and 25' radii, respectively. I figured the best way to do that is with the router as opposed to carving or sanding. I used the LMI radius sanding tool to mark up some plywood and took the plywood to the bandsaw for the concave cut then took an oak board from the old kitchen cabinets and made convex radii on either edge. From there it was a lot of sanding to get the final shape.


    Yesterday I was resawing some 6x8/4 rough sawn cedar into 3rds so the bandsaw had the resaw blade in it so why not resaw for the backs and sides? I have a couple of 12"x9'x8/4 sipo so I cut off 36" and resawed, planed, etc until I had (6) 9"x36"x0.125" pieces.


    It doesn't seem like much but it sure took a long time to do!
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

  11. #11
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    Got the rosette glued in and leveled out. Had to fill in the gap under the fretboard, too. The back halves are glued up and flattened. Next was making a Go-Bar deck. The 1/2" threaded rod was stiff enough to stand on its own. The fiberglass rods I found at HD. They have plastic caps on them and are half the price StewMac charges. The whole thing ran me about $30.


    Jigs for routing bindings and profiling the sides are pretty pricey so I fashioned up a jig.


    I noticed on the underside of those jigs they had something to help ease the guitar body underneath the router. I took a piece of HDMW to the lathe then fit it into the underside of the router base.
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

  12. #12
    I like this thread very much. Your guitar is coming along nicely. I admire the patience it must take to build all the jigs and such necessary to all the processes. You must have an awesome shop too. Great work.

  13. #13
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    Thank you, Lyle. I don't consider myself as a person with enormous patience. In fact there are times I feel like I have the patience of a 4 year old. More than anything, I believe all it takes is desire. The desire to learn, the desire to do and the desire to see it through.

    A few years ago I told myself I could never build an acoustic guitar. And I was right because that belief meant I was never going to even try. The moment I decided to give it a shot, the inability to build an acoustic ended. It was just a matter of desire to see it through.

    This guitar was built with all kinds of mistakes, so many I don't want to list them. But the fact there's resonance when I tap the box made this build a success. I have the woods to build a second learning guitar and one guitar with a master class bear claw soundboard. I've been told it takes 25 guitars before you really get it so, most likely, that pricey soundboard will be used long before I reach 25.
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

  14. #14
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    Julie,I don't mean to aggravate you,but the heel of the neck should be a good deal slimmer,with hollow edges where it meets the body,rather than convex ones. Take a real good look at the heels of QUALITY guitars like Martins or Gibsons.

    I know you have the eye to perceive what I mean.

    At least I'm too far away for you to hit me!!!! ;0

  15. #15
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    Quote Originally Posted by george wilson View Post
    At least I'm too far away for you to hit me!!!! ;0
    That's what you think!

    But seriously, what do you mean by "hollow edges"?
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

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