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About PortlandGuitar

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  1. My dad is a luthier working on guitars for 15 years. He's gone through a lot of different phases and techniques when it comes to leveling, dressing and polishing the frets. It's a tedious and tricky job. Over the years he's developed a few tricks that he wanted to capture in video. I wrote up a guide on how to do this as well. Check it out here: How to level and dress frets
  2. I'm a luthier and when deciding if I've finished an acoustic guitar I'll go over it a look for around 15 things related to musicality, playability and quality. I thought I'd turn that checklist into a guide that others can use to evaluate instruments. I aimed this as a guide to explain to someone looking to buy a guitar what to look for. There's a lot of text, too much for this post. So here is the list below and you can check out more here:intermediate acoustic guitar buying guide The list that I go through is: Top quality , back and sides quality, tuning ease, bridge pin ease, fretboard buzz, fretboard dead spots, neck shape preference, action preference, measuring stiffness of the top and back, mass consideration, evenness of finish, craftsmanship details, intonation quality, pickup quality. My list is by no means exhaustive and there are many things I missed or could explain in more depth or with more clarity.
  3. I wrote an informational article about how wood is bent for acoustic guitar sides and other parts. It's pretty long so I'm not going to post it in it's entirety here. The short version is that steam is really cool. We can bend wood by using only a soaked piece of wood and clamps but it has to be a thin piece. A guitar side is bent using a heating pad and water to create steam at close contact then apply pressure at the middle,upper and lower bout the conform the side to a jig. My theory is that steam lubricates the fibers of the wood to make them slip next to each other.It doesn't cover using a steam box or bending iron. Learn more about guitar side bending
  4. My pictures won't upload, so view the full post here: guitar bracing Falcate Bracing There have been many bracing designs used over the course of Jay’s building career. When he started out with a kit, the bracing used was an x-bracing pattern A good learning experience. There were difficulties present. Shaping each brace to the curvature of the body was a tedious and repetitive task. Cutting them out to the right shape and height for strength and voicing was an imprecise process. A mechanical engineer, Jay searched for a better way. As more guitars were built there were improvements in design. The current guitar bracing patterns that we use is called a falcate bracing pattern. This is our acoustic guitar soundboard bracing This is vastly different than a traditional x-bracing There are myriad reasons to use this bracing system. It is a design inspired by two Australian luthiers. The key is to use a curved bracing system instead of straight pieces. The curved pieces are bent into shape then placed onto top or back. There are six braces in the guitar back or top, three sets of two. They are placed symmetrically on the back in pairs. The direction they are lying is such that the longest part of them is in line with the tension the strings are providing. Running from the read to the bridge and up the sound hole. This provides the maximum amount of support over the axis that the tension is applied while keeping the amount of tension in the minor axis minimal. It is very flexible along that axis this makes it a more responsive top as it can vibrate more freely. There is less impedance to some of the modal resonances and provides a more clear and articulate tone. Another innovation is the use of graphite in making the braces. The braces are made from three pieces. Two pieces of mahogany and a strip of carbon fiber. They are epoxied together and then sliced laterally. The grain of the wood is facing straight up, and the carbon fiber is along the same axis, this provides a significant amount of strength. These are hard to break. Even flexing them, not along the strong plane, is hard to do. They are significantly stronger now the pieces are alone. In addition, the surface area of the brace is minimal an acoustic guitar bracing dimension of 0.3” that’s making contact. Now, we have a strong brace that is providing the most amount of support under the bridge and sound hole. The chances of this guitar undergoing bellying, where the area beneath the bridge swells. This effect occurs due to the tension over long times pulling it up. With the falcate bracing system there’s enough support to minimize this effect. This is one of the advantages of a Portland Guitar Here are the pieces that are used to create a brace The braces as they are placed onto the back or top, smaller in the final form The next benefit of the acoustic guitar bracing patterns is a building advantage. Each of the curved braces is already part of a circular piece. Since the top and back want to be bowled surfaces at the end, the braces can be placed directly onto top or back and glued into place. There is no sanding of the bottom of the braces to conform to the curvature of the top. The braces are already conic sections that lie within the bowl. Once they are being glued on in the go-box the top or back is forced to take the round shape of the mold and hold it in shape. This reduces the amount of time spent on repeating sanding by a lot and frees up time to spend on detailing. The last innovation with the braces is the process of tuning. There is a misconception in the luthier world that tap-tuning the top will account in better voicing and sound. Sanding away parts of the braces in special spots doesn’t have a large effect on the tone. The thickness of the top has more of an effect then small places here and there in the braces. The shaping of the braces tapered down to a point is a good practice. Our process is to simulate the tension from the strings and then sand the braces. The top is put in a jig with the sides supported to simulate a guitar body and top. The top has a lever arm with a weight hanging off it. This is how the torque is applied. We know that at one meter or so and at 2 inches of deflection with a 10-pound weight we can simulate the 200lbs of tension on the top. If the deflection is less than two inches than we know there is too much strength in the braces. The braces are sanded down at their modal points to bring the tension down. This ensures a minimally braced top and thus one that has the best tone. The act of sanding down the strength of the braces allows for greater flexibility and more vibrational response. This improves the tone and responsiveness of the guitar. We built this with a jumbo body and the feeling on the body was incredible. Here is the top in our contraption: This is the lever arm attached to the top which simulates the tension. When the weight drops two inches, we know that the right amount of force is being applied to counteract the tension. Here’s what it looks like to sand the braces This build was for an acoustic bass guitar, so the braces are rather thick Here is the guitar back bracing In a comparison between our guitar and a Collings guitar we can see differences due to the acoustic guitar bracing. We can see a quantitative difference in these two-frequency response graph the Collings guitar does respond on some notes, but our guitar is responsive consistently on every note to a great amount. The dip that is seen is how much the body resonance interferes with the note that we hear. This is where the guitar becomes special in how it sounds. The amount of variance indicates that the guitar is moving quite a bit and that the air cavity is coupled very well to the top and thus responsiveness. Collings Guitar Portland Guitar There are many different variables in this experiment, bracing being one of them. First the woods were different, which could have an effect. The Collings had rosewood with a spruce top, while the Portland Guitar had ebony with a redwood top Second, the Collings was a dreadnought while the Portland Guitar was an OM. Despite these differences there must be an explanation for the spike that we see across all these strings. Some of the responsiveness is inherent in the top that is used. The rest I’m willing to contribute to the bracing pattern. This phenomenon contributes much to how we interact and feel the guitar.
  5. A client sent us his seagull guitar to retrofit, he heard about our intonation improvements and wanted to try it on his instrument. Jay hadn’t performed this task before but being an engineer, he thought it a good task to take to help spread the bridges to the world. A jig was made to hold the guitar in plate while a new channel could be routed. A scary thing to do once you put someone’s favorite guitar in the surgeon’s chair. Fortunately, everything came out a success and the intonation was improved on this guitar. The improvements were measured before and after the bridge was put on so we got a good view of the changes the bridge and saddle can make. I can only fit 4 of the pictures in here for some reason. Check out the analysis of the intonation and a complete photo journal of the retrofit at Split Saddle Bridge Retrofit
  6. The rosewood circle behind the soundhole looks nice. It doesn't have any function except being an extra piece of art
  7. I recently finished these Brazilian rosewood OMs. One has a western red cedar top while the other has adirondack spruce. I have videos and more pictures of them available at my website:Portland Guitar
  8. Hello Project Guitar, We are are huge cnc fans. Here's why The use of cnc in building a guitar is a game changer. The combination of machine precision used in a creative way with hand finishing craft behind it is a powerful combination. This tool has let us build a better guitar, in less time. We can repeat the some of the tasks which lets us spend more time working on a piece by hand. Placement of the frets, radius of the fretboard and bridge pins for scale length are derived from formulas, it is nearly impossible to get these in the exact right spot in practice. Small amounts of variance add up and contribute to a less articulate instrument. We can make these cuts with precision that ensures it’s in the exact right spot. The cnc has opened a new pathway for art. The interlocking wave is a signature of Portland Guitar, its creation is in the small strips of wood that are routed into waves. Many designs are possible. This is not possible by hand. Our split saddle bridge has many small channels, and the nut itself is at an exact angle. These are possible using small bits to get into the nooks and crannies. Since we can create multiple pieces of the same size, we can change the action with the addition of different plates. We can achieve a near flat fretboard with very little sanding and altering of the crowns of the frets. The fretboard is planned flat and so is the top of the neck which the fretboard sits on. These flat surfaces ensure that when the frets are pressed in they are level. The use of the cnc has opened a wide variety of opportunities. This is our cnc. It’s a Laguna IQ pro ATC, we built a box for it and but acoustic batting in the sides. We’re running out of a garage in a neighborhood in Portland. So it’s important to be quiet. One of the first places the cnc is used is on the top. We use it to route the rosette pocket, sound hole, and bridge pins. Here is the rosette in place One of the biggest improvements to our process is in the joins of the top and back. A single profile path can be used to put a fresh edge on our two pieces. Then they have perfect contact when glued. They are book matched when cut so the grain is symmetrical. The heel blocks and neck blocks are also made in the cnc. The repeatability and uniform nature of these blocks allows us to create multiple necks for the same guitar with relative ease. The artful purfling we use is an interlocking wave. Strips of wood are taped down and then routed out in bulk. we use the cnc to make the fretboard. It allows us to put in an exact radius instead of relying on a jig. The frets are always in the same place with just the right width. It makes putting in the frets simple. We can route out pockets on the fretboard, so instead of mother of pearl dots we can include unique fretboard art. the cnc at work we also use the cnc to route the neck here it is doing the top In order to level the top of the neck we running a planning path, but to get it roughly correct two machine plates are placed over our clamp with two magnets underneath , then the top of the neck can be placed level with those plates. here it is working on the headstock. We’re able to use large metal table clamps to hold in the parts for the headstock and neck top. They also come in handy securing the head during routing of the back. Here’s the router working on the back The neck jig is two pieces, the bottom one is keyed into the spoiler board on the cnc bed. The top piece holds the neck. It has blocks which are keyed to the bottom board which allow it to be rotated while holding a center. Here is work on the side of the neck One of the last places we use the cnc is in making the nut. The precision we get in creating the right radius over the fretboard is unmatched. It lets us alter the action on these builds quickly. There was too much to fit into this post. Check out some videos of the cnc in use on the neck and more at my website. https://www.portlandguitar.com/blogs/features/cnc-in-acoustic-guitar-building or check out some of the guitars at https://www.portlandguitar.com/
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