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Old 06-27-2020, 06:04 PM
Portland Guitar Portland Guitar is offline
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Default Portland Guitar Four Jumbos and Parlor Brazilians

We’ve started a new round of guitars. The idea when building is that the set up time is going to be the biggest pain point. Getting out each jig for the specific job it does takes time. Setting up the clamps and files for the cnc is also time intensive. To fix this the practice of building many guitars at once is being tried. This allows the jigs and setups to be used multiple times while out.

This round is another set of Brazilian rosewood guitars. We recently bought a few more sets of this so the time to build with it is now. There are going to be two 14” bodies and two 16” bodies. As well there are two tops, Adirondack spruce and western red cedar. These combinations make four guitars. Here are pictures of those woods. The tops are already joined and the rosette channels are routed.










The neck blanks as well have been completed





Next is the sides, here they are bent with curfing on





The blocks need to be glued in to hold the two pieces together





Observing his work





The edges must be sanded



A stack of frames





Now it’s time for the fun activity of cleaning out the shop. So much wood dust.





These are going to be some great guitars. I’m excited to see and hear what they will be like.
I wrote a blog post about falcate bracing and x-bracing. I need to update it with some new information but
it's available here: guitar bracing theory
It's too long to post here.

Last edited by Portland Guitar; 06-28-2020 at 07:36 AM.
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Old 07-03-2020, 06:00 PM
Portland Guitar Portland Guitar is offline
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The frames have been made for the four guitars. The tops have started to have their rosette channels routed. The next steps are to put in the rosettes for each top. Using the cnc to route those channels. Our goal is to get a body together. The braces need to be made and glued into the top and the back. We only have one go-box, which is used to apply the pressure needed to glue the braces in. There are eight pieces of wood that need to have braces glued in. Only one or two can be glued in during a day so this step is going to chew up a lot of time. An important part will be getting the process down to make a conveyor belt to get these all glued together in a timely manner. The steps happen in a few parts. The first one is to cut out the strips needed to make the braces. These are then bent over a form. Then the carbon fiber is cut out and glued into the bent braces. The braces must be cut into individual pieces then they are placed on a top or back and glued in using the go-box.
Wood bending has two main components: heat and water. These serve to loosen the ligands in the wood and makes them more pliable. When bending sides. there is continuous heat that is added at the same time as the water. The water serves to distribute the heat and make sure that every part of the wood is hot. The water absorbs into the fibers and acts as a lubricate between the fibers allowing them to move more freely. The amount of water vs heat needed various.

The strips of wood are soaked in water. The water can be warm but it’s going to cool down over the time that it’s soaking. This step isn’t to add any heat to the wood it’s only to make the water absorb through the wood. It’s left in the sink for about thirty minutes. It can be left in longer but at a certain point the wood has absorbed all the water that it’s able to. The strips are thin enough that this doesn’t take a long time. After the thirty minutes are up the strips are tested by giving them a little bend. If it’s pliable then they can be taken out. If they are still tough, then time to soak for longer. The braces only need to bend enough to fit into our forms. The forms have nice gentle curves so it’s not asking the wood to bend far. It’s much less than bending the upper bout of the side, a notorious bend.

The wood is clamped into the jig and put in the oven.

Here’s Jay taking the braces out. It’s hot! Those clamps absorbed a lot of heat.

They are left to cool down and hold into the form. It would be a problem to release them from the jig now and have them relax back to a flatter position.

The carbon fiber is rolled out and taped off in sections. This helps keep the end strands together when cutting it out.

A piece of wax paper is placed on top of the form, so the epoxy doesn’t glue the braces into the form.


Glued together.

The braces are cut out on the band saw and then placed on the top in a pleasing shape.

They are glued in using the go box. Glue is sticky and slick at the same time, so it takes some care to fit the braces in while pressing down on them.

I wrote an article about wood bending. Most of the info is probably repetitive for most people here but you can check out the guitar side bending article

Last edited by Portland Guitar; 07-06-2020 at 05:40 PM.
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Old 07-13-2020, 07:33 PM
Ergoetal Ergoetal is offline
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These look great. Any progress on these?
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Old 07-16-2020, 09:16 AM
Portland Guitar Portland Guitar is offline
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Thank you! Yes there has been, I'll post an update today.
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Old 07-16-2020, 10:39 AM
Portland Guitar Portland Guitar is offline
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It’s been a few weeks since the last update. The shop needed to be rearranged for a replacement bandsaw and drum sander. It was a perfect time to get some cleaning and maintenance done. sometimes it’s important to have a less dusty shop.

Frames, braces, tops, backs and glue create the bodies of these guitars. The braces and frames are complete, onto the tops. The same style and design will be used for each one. An amboyna burl rosette with a black white black border. First a little work to complete the frame.



A bottom decoration is put in to hide the joining line. The inlay and wood insert are glued in. It’s a messy process.



It’s cleaned up with a chisel and sandpaper.
Next, we turn to the top and the rosette.



Channels are routed in the cnc then inlay is glued to the outer and inner edge. Pressure is applied and a drop of glue seals the deal.



The pieces of the rosette are routed out. To conserve space the circle is broken up into four quarters. They are tessellated in a rectangle then cut out. Double stick tape keeps them attached to a spoiler board. To be detached, heat is applied.



Glued in place. Some adjustment required.





The finished product on spruce and cedar

A large detour to create elegant purfling ensued. Many ideas swirled for this series. The wave designs worked well for the last series. A good design, but a now comfortable technique. A new purfling pattern is desired for this set. Nature and symmetry inspire the set.

Technical difficulties present the next challenge. The idea is to make long thin strips using the bandsaw. Then cnc the pattern.

It can make any pattern it’s given. But different router bits used will affect the size and resolution of the image. Purlfing is not wide and looks better when in thinner strips. To accomplish this precision a 0.05” end mill bit is used.
Small strips mean small details. Thin purfling and patterns want to break off and ruin the run.

The strips bend around the lower and upper bouts. This provides a limit on the thickness in certain places.



Here is the cnc at work. The wood used for the first trial was bog wood. It’s light, hard to see in this picture. It’s taped down to a spoiler board. An added problem is that the purfling can break while being pulled up.



Using the heatgun and a scraper the pieces are pried up.



One of the designs that worked.



Another design that worked.

There was limited success making these. The key design snapped in multiple places many times.

The number of strips that were usable ran out and attention was turned to finishing the bodies once again.



The back was sanded in places.
A set of back and sides were finished and glued together.



The body glued together.
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Old 07-23-2020, 03:52 PM
Portland Guitar Portland Guitar is offline
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The bodies are complete! It’s the end of leg one of this batch.
Here are the last pictures to catch up.
Laying the glue down on the curfing. A liberal amount is applied to make sure all the edges are filled.



Scraping squeeze out from the inside of the body. No one will see this, but it’s important for the spirit of the instrument.



We’re installing K&K pure mini pickups on this batch. They have three contact pads that go underneath the bridge.



The four bodies completed





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Old 07-23-2020, 04:34 PM
jaan jaan is offline
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Default Bracing

Very interesting bracing under the hood! I don't think I've seen that style before. Does it produce a more modern voice? Is it better for fingerstyle or flat picking?
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Old 07-24-2020, 12:37 PM
Portland Guitar Portland Guitar is offline
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I would say so, It provides less stiffness and mass for the top while retaining a lot of the strength. boosting mainly the low end. It's a matter of preference, I think it's better for flat picking.
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Old 07-27-2020, 12:25 PM
Portland Guitar Portland Guitar is offline
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We’re around the half-way point for all the guitars. The bodies are together and ready to go through the marquetry steps. The neck blanks are ready, but they need a fretboard. That’s what we’re taking care of next. There are four to make and all will be in similar styles. We’re having success with our colored inlay so there will be more of that for the fretboard markers. Snake wood binding and a white border binding will frame the bottom edge. A white border will also frame the top.

Every job in the CNC starts with the design process. Sometimes it takes hours and sometimes days. For creative designs, the ideas percolate for weeks.



There are two major tool paths used to create the fretboard, a radiused profiling and the fret slots. First the radius is put in. This is done with a ball end bit



A channel is routed for the white border then glued in.





Then the slots are routed.



The pigment is applied after the fretboard markers are routed. Channels for the inlay are also done. This was one of the first times. A cyanoacrylate with the green powder proved insufficient. Too many cracks and uneven fills. The process later changed to adding the pigment to an epoxy resin.
Six fretboards were created this round. The goal was to get it close to perfect. During steps like these, it’s easy to repeat most of the work, it’s possible to retry a few times. This was one of the early and unsuccessful trials.





There are lots of cracks in the inlay and uneven edges on the binding. It wasn’t right so another was made. On the third trial it started to work. Here is the epoxy painted on.



Drying overnight.



Time to put in the frets. CNC is used to make 20 blocks of differing radius, used to press in the frets. It gives an even fit and minimizes the amount of work needed later.



Three stages



The tang of the frets needs to be ground down so they don’t stick into the binding. They are put in this holding device then sanded off.





This batch is complete. It turned out nice in my opinion. Here are three.

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Old 07-27-2020, 01:04 PM
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Interesting to watch these come along! Looking GOOD!

Carry on and stay vigilant and well

Paul
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Old 07-28-2020, 06:19 PM
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A lot of work done there, sure looks nice when done the way you want them to be.
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Old 07-29-2020, 04:26 AM
Portland Guitar Portland Guitar is offline
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Thank you.

It's constant struggle to be satisfied with them. A critical eye has its advantages and disadvantages.
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Old 07-31-2020, 01:46 PM
Portland Guitar Portland Guitar is offline
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The fretboards are done. They are epoxied into the fretboard and the neck is complete! Marquetry is the last step before moving onto finishing. This is time intensive and detail oriented. The plan for the purfling moved towards a more traditional style. Herring bone with snake wood binding and a black-white-black inlay beneath the binding. The work can’t be repeated this time, mistakes are permanent.

The snake wood, fresh out of the bending machine. So much texture.



Routing the channel for the binding and purfling. A router on a radial arm moves around the body of the guitar to make a channel for the inlay to sit in.



All four had their channels routed at the same time.



At this point the path of these guitars diverge. The parlor with spruce advances further than its peers. The marquetry is time-consuming and tedious. It’s mentally exhausting to do and takes a whole day. Doing this four times in a row would be draining. There’s a certain amount of reward needed to offset the slog. Instead of doing marquetry on the other three, this one is finished instead.
The starting place for the inlay is where the neck meets the body.



The channel is cut out with a multi-tool



Then cleaned up with a chisel



A strip glued in



Cut off



The overhang is sanded until the neck, slides in.



A good fit




The purfling is pressed in, then a drop of cyanoacrylate is added to hold it in place.



This is done all the way around the guitar, then sanded down.



Clean up



The final form

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Old 08-02-2020, 04:50 AM
ZacInSC ZacInSC is offline
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Wow! Those are pretty!
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Old 08-04-2020, 04:28 PM
Portland Guitar Portland Guitar is offline
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Thank You!

The body and neck are finished on the emerald guitar. The first in the series is almost ready to finish. A great guitar so far, but an uphill battle to get the details right. Jay is feeling good about this one. The pace of the build slowed down at this point. The next pictures took place over around 2 weeks. The idea here was that all good things happen slowly. The build has been successful so far. No reason to ruin it by rushing forward and applying a poor finish.

After finishing comes set up. This is painless as the CNC makes our nut, giving us pre-cut slots and even string spacing. Getting the height of the nut is easy using a sander. After this there are a few more details, like dots and a truss rod cover, to add.

The body and neck are sanded down to 800 grit to remove all the scratches. Most of the scratches are put in by the drum sander, so using the 80 grit is the most important part. The largest scratches are the most troublesome. This takes twice as long as predicted every time. Once it’s completed the instrument feels amazing to the touch, silky smooth.



The acrylic lacquer is air brushed on. While spraying, It’s important to get even layers. The brush must be held a certain distance away to make sure the right thickness is appled. From what we’ve been able to figure out, finishing is an inexact process. It has many variables that change daily. Temperature, humidity and others affect the way the lacquer dries and cures. What we do is the best process so far that we’ve found through trial and error.



It dries then is sanded down. The amount of time it spends drying influences how hard it is when sanding.



A layer is applied and then sanded off down. The wood is like a landscape, it contains high and low spots. The goal is to raise everything to an even level. The first layers fill in the valleys in the wood, then the peaks are sanded down.



The same is done with the neck



Polished up and looking fine



The bridge is made then glued on. The finish is thin enough on the top that it can be sanded away to allow space for the bridge to be glued on.



The finished bridge. We made some changes to the split saddle bridge since the last time it was pictured. The changes were made to make the presentation cleaner. The saddle plates were turned into a singular saddle plate. The gaps between the edges were eliminate and the edges have a lift tab to remove it. I think it looks better



The nut is made





The neck is put on



The nut is trimmed to size. A pencil is used to pull the strings up then the nut is removed and sanded down. Our sander is a lathe that has a piece of sandpaper glued to the wheel. The variable speed makes it excellent for fine sanding work.



The truss rod cover is put on. In the past truss rod covers weren’t used. We heard feedback from multiple people that a truss rod cover looked better. The thought process behind leaving one out was that in a performance guitar the player wants to have easy access to the truss rod. Unscrewing a cover creates a burden. This was solved by using magnets in the cover and the truss rod slot.



A few more details were cleaned up and presto! the guitar is finished



The next round of pictures will be the final product shoot.
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