Wednesday, June 21, 2017

Now for Something Completely Different

About a year ago, I told the story of a guitar project I was starting on.  To summarize, a friend had given me an odd "junk guitar" with most of one side cut away.  The story is that the manufacturer, Breedlove, had made it as some sort of demo piece that showed how well they were made by showing what the insides of the guitars were like.    
It has a solid Sitka spruce soundboard (top), which isn't uncommon once you get past the very cheapest guitars; the back, though, is solid rosewood and that's something I expect to find only in fairly high end guitars.  The closest equivalent I know of on the market today seems to be the Fender Paramount PM-3 Deluxe at a K-buck.  The sides are rosewood laminate (plywood), but a guitar's sides are largely structural and don't affect sound very much. So while it has an obvious problem, it's basically a good guitar, not one of those cheap, plywood guitars for beginners.  In other words, while it's a junk guitar because of how it was cut up, it's not a "junk guitar".

Last September, I replaced the missing parts (with the exception of the electronics) to make it playable, and I've been playing it at least once a week as my primary acoustic guitar.  It sounds remarkably good.

All the while I've been trying to come up with a way of restoring it.  The problem is that the shape of that cutaway isn't a piece of an oval, a circle, or anything that looks like a conventional guitar's waist.  I'd have to turn the cutout shape into something I could match exactly to make a solid top with the right shape, and I'd have to rebuild the top and back.  I might have to remove the neck.  I'd need to replace many of the braces inside the box; you can see some of the braces on the back; the braces on the top are a more complex pattern and really a science of their own.  Getting the wood to rebuild the top and back would essentially mean buying the wood to make a whole new guitar, and it would probably take more work than making a new guitar from flat pieces of wood.

What about just putting a piece of wood over the hole?  I started looking into that and found it to be harder than you'd think.  The wood used in guitar making is very thin compared to standard lumber, which has lots of advantages, but means you just don't find it at the Orange or Blue Borgs, you have to buy it from a luthier supply place.  After you find it, the wood's typically sold as a separate top and another species sold as the back and sides.  From time to time, during thickness planing or sanding, a side will get broken and the remaining piece set aside and sold as a practice or "orphan" side.  For a few reasons, I had decided I'd like a light wood, preferably figured maple.  The problem with that is the places who sell these orphan sides tend to say, "no selection"; "you'll get what we have the day we get your request".   One of the major online suppliers told me they'd be happy to sell me two sides at full price, if I'd like, which came across as less helpful than they might have though. 

Somewhere along the line, somebody suggested I replace the side with a piece of clear plastic.  The guitar will always be an oddball, one-of-a-kind instrument, so since it was originally intended as  a showpiece of what it's like inside a Breedlove guitar, this will keep it that way.  I finally went down this road, using some clear plastic left over from building my mill's enclosure.

Since holding the plastic to the guitar has to be designed in, I decided to use pieces of wood called kerfing, for the multiple saw kerfs cut in it.  The first step was to cut this into pieces and glue them to the top and bottom of the body, emulating the way the existing kerfing is positioned.  This picture shows the bottom kerfing already glued in place and the top kerfing being held by rubber band clamps. 
With the kerfing glued in place, the next step was to rough form the plastic.  I made a form by tracing the outline of the body's cut onto some scrap 1x pine, cutting that out with a jigsaw and then smoothing with sandpaper.  After that, I clamped the plastic to the high spot on the form and heated it with a hot air gun.  As the plastic softened, I could push it down onto the form with a long-bladed screwdriver and after a few seconds, it won't spring up anymore.  Much.
Then it was time to go through a cycle of test fit, mark overhang on the plastic, cut it off, and repeat.
As you can see, I put a sound port on the side, like so many high-end custom guitars have these days.

Finally, the real purpose of the kerfing.  In a production guitar, the sides are glued to the flat surfaces on the kerfing.  I thought that for this guitar that it might be best to use wood screws on the sides, because wood glue doesn't work on plastic and epoxy is too permanent.

I suppose it's typical for me to say I'm not sure if it's Done done.  Before I smoothed the plastic to make it match the body's top and back,  I put a new set of strings on it and played for a half hour.  Adding the side didn't mess up the sound, that I can hear.  With the sound port where it is (even though it's not perfectly centered - aarrgh!), it still sounds good from where I'm sitting.  The second thoughts that I have about being done center on how butt ugly it is.  I might do something like stain the light colored wood of the kerfing to make it a bit less glaring, and in-your-face.  I need to learn a bit about options and what I can do to make it look a little nicer, if possible.

On the other hand, it's not like I'm playing in clubs and lots of people will see it.  It'll be under my right arm and held up against me while I'm playing.  Then it will live on a stand until the next time I pick it up.


  1. My Eyes! My eyes! yes it is ugly. Sorry. :)
    If you want to make it pretty, go find a piece of E. Indian rosewood, fit it as a side, and continue the purfling, abalone and all, around the curve.It will look like some rock star special whacked-out order. How big a piece of rosewood do you need? Not thickness, but length and width? Or some other wood? Maybe I have something laying in the bin.


    1. An adventure! The widest point is 4-3/4" and it's 13" long.

      I figured instead of it being an invisible repair, no matter what I do it's going to be a conspicuous, "Cletus! Look at that!" repair. Let's say I can get the edges really smooth and tight seams. I'm guessing the chances of getting matching abalone is about zero. On the other hand, I watch Dan Erlewine's videos and it's amazing the effort people go through to match the aging of the finish. This guitar has poly-something-or-other on it, so the finish is going to be rough to match.

      I was thinking flamed maple or even quilt. Why? First, I understand it's relatively easy for a first-timer to bend. Second, since it's always going to be a "look at that!" area, give 'em something to look at!

      I'm open to suggestions. My wife says, "stop poking at it - call it done".

    2. Abalone and purfling is a call to stew-mac or luthier's mercantile , or even Grizzly- the pearl width is the thing to match. Usually it is straight pearl, cracked in short sections to make the curve.
      The "acoustic guitar forum " has a build and repair section- there are some real nice and astonishingly capable people there if you need advice. I recently made a new neck for an old D style and they were a huge help- in my case it was not the woodworking that was an issue, it was knowing WHAT to do- how much neck angle, how much slip will the dovetail take up under vs dry fit, that sort of thing.
      Despite my snark, the important thing is -does it sound good? Sure looks like it was a high grade instrument- Breedlove guitars are rated very highly by folks in the know.

    3. I think it sounds really nice. I know that current production Breedloves, only their highest end guitars, use some high tech tools to decide how thin the top needs to be and they say they make the treble side thicker than the bass side.

      Back during Winter NAMM (I think), there was a video demonstrating tapping on a sound board with a spectrum analyzer program and determining how to make the top based on this analytical method. I just spent a long time looking for the video and this sound profiling page and video seems like the closest I can find.

      I am a member of the AGF, although I don't read there regularly.

      My mental stumbling block here is that I'd like to build a really nice acoustic and I think it takes building two or three to get there. Is it smarter to just buy a nice custom than to build three to get one?

    4. That depends on what you want. You seem to be a guy who loves to make things. There is great pleasure in making cool stuff. So if the time is there, go for it. On the other hand, if you just want a guitar to play, go buy one. This is perhaps the best buyers market for fine instruments I have ever seen. The boomers are aging, collections are shrinking, money is tight- out there in the real world, as you have mentioned in other posts, the economy is not doing great-so a lot of used guitars are selling low.
      Some of the most interesting posts in the builders forum at AGF are not the pro builders, but the guys who just jump in and start doing-I am an agonizer and planner about this sort of stuff, cross every T sort- some guys just start winging it -by the time I could build one "perfect" one, they would have built seven, every one getting better. It is inspiring because all the fancy expensive tools and woods are just not really necessary- like every other avocation, a market has developed to supply all sorts of gadgets. When I built the neck for my guitar, I did not go to a supplier and spend $100 on a special "guitar wood" mahogany neck blank,just found a nice piece of dry mahogany and used it. Having a scrap bin is good..

  2. It might also be worth taking to a woodcraft store and see what ideas they have. The ones in my area tend to be staffed by older retired guys who work there for fun and the employee discount, and often have great ideas for various projects. Your mileage may vary. I'd be surprised if they had much experience with instruments, but if the material doesn't affect the sound much (and your experiment seems to confirm that) then in terms of making it look good they might have some good ideas and material.

    1. Interesting thought. My nearest Woodcraft is about 80 miles away, so I don't usually go there.

  3. Here is a half-serious, half tongue-in-cheek suggestion - run it past the designers at Kel-Tec. You would certainly end up with something unique. They are closer to you than Woodcraft, and might come up with an idea in your caliber of choice :-)