Acoustic Constriction Lab - Week 3

   I started the week by preparing my guitar side ribs to the appropriate thickness and length for bending. I added moisture to the mahogany by running the pieces under warm water briefly before wrapping each rib individually in paper towels and tinfoil. I placed a heating blanket on the rib and sandwiched it between two spring steel sheets, placed it on the side bending mold and started the heating process. While applying heat for three minutes, I slowly pressed the center waist clamp down. Next, I bent the lower bout by slowly pulling the spring clamp, repeating the same process for the upper bout.

  

  After the bending was completed,  I let the rib sit in the mold and come back down to room temperature. Once cool to the touch, I reheated for another three minutes and let it cool back down again. 

  The side was now ready to be removed from the bending mold and transferred to the body mold, repeating the same process for the second rib. After placing the ribs in the mold, I clamped the cauls in place to prevent the wood from springing back and left them to sit over night. 

  The next day, I removed the ribs from the mold and trimmed the ends to size. I used mahogany to construct my neck and tail blocks, and glued them to the ribs joining the sides together. I clamped the blocks heavily and allowed the glue plenty of time to set. 

  After drying, I installed my mahogany kerfing to the inside edges of the ribs. I wrapped rubber bands around the ends of clothespins to increase the clamping pressure, and used them to firmly hold the kerfing in place while bending and gluing.

  While waiting for the kerfing to dry, I installed my center strip and braces to the back of my guitar. I used sitka spruce for the center strip, and Adirondack spruce for the back braces. I glued them using the go bar clamping deck in a 20" radius dish. Once dry, I shaped the braces with a chisel and finished them off with sandpaper to give them a clean appearance, as they will be visible through the sound hole once assembled. 

  With the weeks end, the pieces of the sound box are completed and ready to be glued together. Next week will be spent assembling the body, installing the binding, and laying out the neck and fingerboard. Step by step, its all coming together. 

- Justin Ness 

Martin or Gibson, what's the difference?

I like comparing the designs of the classic Martins and Gibsons because while I love the sounds of both, they have distinct tonal differences. The tonal differences and the design differences have helped me to form some opinions and understanding of what I can do as a maker to affect the sound of the instruments I build.
Just to be clear, I'll talk about pre war Martin Dreadnaughts, and Early 40's Banner headstock Gibson Dreadnaughts I've gotten to work on and examine. Trying to describe sound is always tricky, but in general I'd say the Martins sound fuller, warmer, and perhaps a bit louder. The Gibsons have more edge, focus, and clarity. Just my opinions, and I'd really rather you listen to as many as you can and formulate your own ideas on their sounds. I'll list the main design differences, and then go into more detail about each of them in future posts.
Body shapes are similar enough that if you take the Gibson sloped shoulder body style and do everything else in a Martin style, it sounds like a Martin. They are both X-braced with 2 lower transverse braces and 2 finger braces off each side of the X-braces.

3 of the main design differences are;
Scale lengths;
       Gibson 24.625", Martin 25.4"
Arch built in to the top;
       Gibsons had quite a bit of arch, about a 20' radius,
       Martins were built flat, though over the years string tension has pulled an arch into them
Angle of the X-braces;
        Gibsons were around 103 dgrees
        Martins 98 degrees
I've seen some variation from these numbers in the guitars I've seen and I'm sure there are more. These guitars were in ways more hand made, though in factories by many pairs of hands, then most of the modern instruments from individual makers. It all depends on your definistion of "hand made", but my point is there was some variation.
Now go play lots of cool old guitars and we'll talk more about all of these differences and others.

Acoustic Construction Lab - Week 2

  Week two of Acoustic Construction Lab was spent focusing on bracing the guitar top. I chose to use a few pieces of Adirondack spruce that I had purchased, tilt the bandsaw table to match the end grain vertically and re-saw the spruce to get the best quartersawn stock possible. After cutting my braces slightly over-sized, I thickness sanded them to width. The Larson Brothers are known for their unique x braces consisting of a three-ply lamination, with a strip of hardwood between the spruce. I decided to use rosewood to do this for my upper transverse and x braces. Their OM sized guitars also have a top radius of 15’, so I used an edge sander jig to shape a radius on the edge of the brace that is to be glued to the top. After all my braces were radiused and cut to size, I notched and fit the x braces together. Moving right ahead, I began the gluing process using a go-bar clamping deck. I placed a dish with a 15' radius in the bottom of the deck, and bent strips of maple to apply clamping pressure and hold the brace firmly in place while letting the glue set.

  The first round of gluing installed the x brace, as well as the upper transverse brace that has a radius of 25'. After the glue had completely set, I started tapering and shaping the laminated bracing using my block plane and chisels. 

  Next I prepared my lower transverse and finger braces, by tapering and rough shaping them to size. These pieces were constructed using the Adirondack spruce.

  I used the scrap Adirondack from re-sawing my brace stock to construct small clamping cauls to fit over the finger braces, preventing them from being damaged by the wood strips used to apply the appropriate clamping pressure.

  Both lower transverse braces were also installed during round two of gluing, they were all pressed in a 15' dish and allowed two hours to set. 

  For the third round of gluing, I installed the maple bridge plate as well as the upper graft, sound hole braces and x brace cap, all made from scrap Sitka spruce pieces left from my guitar top. 

  By the time Friday rolled around, the top was completely braced and I spent a good part of my day carefully shaping the braces with a finger plane and chisels. While my guitar brace work is laid out true to the Larson Brothers design, I decided to shape the braces themselves in a more triangular approach that closer resembles the Larrivee guitar bracing. 

  During my down time waiting for the glue to set, I started to prepare my Honduras mahogany back and sides for week three. I joined my back, thickness sanded it and cut out the shape slightly over sized. I also thicknessed the sides and prepared them for bending. With every new day the pieces continue to come together and resemble a guitar more and more. 

- Justin Ness

Acoustic Construction Lab - Week 1

  One week into my acoustic guitar build and I am already finding myself dreading the weekends, i would rather keep working. Its amazing how fast the day flies by when you are building. Over the three week winter break I left my materials to acclimate in the lab environment. I chose to build a Larson Brothers Orchestra Model with a sitka spruce top, Honduras mahogany back and sides, mahogany neck with ebony fingerboard, Indian rosewood bridge and head cap veneer. 

  The first week of Acoustic Construction Lab was spent building our workstations, templates and laying out our desired neck dimensions on the blueprints. We then moved ahead with jointing and thickness sanding our tops. Having never used hot hide glue before, I decided to use it for this process. With such a small window of time before the glue begins to set, getting the two pieces placed together and clamped in under a minute and thirty seconds was a bit of a challenge. In the end it worked out just fine for me, and I am happy that I took the time to gain some experience using the hide glue as I intend to continue to use it for various glue joints throughout my build. 

  Next I cut out my body shape leaving the wood slightly oversized. I laid out the rosette in pencil, and sealed it with a coat of lacquer to help prevent end-grain splits while routing. 

  I have become comfortable with most of the powertools that we have available at the school, but a router is the one that I have the least experience with. The thought of cutting a series of perfect circle groves into my freshly joined and sanded spruce top was a little scary at first. I picked out a classic herringbone rosette and decided to add an inner ring by inlaying two purfling strips together for my desired thickness. I took my time measuring my cuts, practicing on a piece of scrap wood. When I made my final cuts, it worked out just as I had planned and the inlay was complete. 

  I used a thin bead of glue in the bottom before inlaying the rosette and ring, clamped it and let it dry. I then used scrapers to remove the excess height, bringing it down to the top level and finished by sanding it out. 

  After this process I took the top back to the router and cut out my sound hole. With the rosette completed, I started laying out the bracing on the inside of the top. I am bracing my guitar in the style of the Larson Brothers, and I made my marks by using a templet and cross referencing my blueprint. I made a cut list of dimensions and began cutting my bracing stock using quartered adirondack spruce, with a rosewood laminate for the upper transverse and X-braces. 

  Just like that, week one has come to an end. Week two will be spent bracing the top, and getting the back and sides joined and thickness sanded. It is starting to take the shape of a guitar. 

- Justin Ness

Electric Design

There is a new offering as part of our Electric Guitar Building certificate which is a one credit Electric Design course.  Historically the design and blueprinting process started in the spring semester Electric Construction course which would take at least two full class days.  That class time becomes incredibly valuable toward the end of the seven week building process.  By creating the fall Electric Design course students have more time to plan what they'd like to build, complete the design process and have a working drawing to help them choose the correct material sizes to order for spring.  Not only that, but it will save all of the students valuable time in the actual building process.

Here is a design nearing completion.  The necessary dimensions are listed so someone can get the answer they're looking for without ever needing to measure the drawing. 

It can't be overstated how important the design and blueprinting is for a successful build.  As you work through the design on paper (or in a CAD program) problems with the idea will come to light.  You'll get a sense of how something will be constructed and plan ahead to make the process as smooth as possible.

This years students have the advantage of knowing all of the dimensions before they need to order wood for the build.  Making sure the material is over-sized enough will likely avoid some improvisational solution during construction.

On the first day of Electric Construction this spring, students will right away begin making templates.  They will want to have their finished blueprint with them as reference during the building process.  We're hoping these changes allow for a little more breathing room during the build for when unforeseen issues or mistakes pop up.  This should translate to a cleaner "fit and finish" to each students instrument.  After all, the fit and finish are what skilled luthiers will be looking at as they consider hiring one of our graduates!  We encourage students to focus on building a very clean, well-built simpler design for their first build. 

Here is the guitar from the drawing coming together.  This instrument was built in an early school year.

So what does this change mean for students coming into the Guitar Repair and Building program at Southeast Technical College?  The majority of credits required for the building certificate are already a part of the diploma program.  In order to complete the certificate students need to sign up and successfully complete the new fall semester Electric Design class which is a prerequisite for the Electric Construction course in spring semester.  The other fall courses needed for the certificate are also prerequisites for the spring building course.  Once students successfully complete the spring Electric Construction and Intro to Finishing course they will have earned the certificate in addition to a diploma.

Students in our diploma program that do not plan on building an electric guitar in spring are also welcome in the fall Electric Design class.  Taking the class would help them understand electric guitars if they are unfamiliar with them which very well might help them as they enter a real world shop setting.

If you would like more information about our Guitar Repair and Building Program at Southeast Technical please contact our admissions department anytime!

Here are all of the courses which make up the Electric Building Certificate:

GTRB1414	Guitar Overview Topics (fall)	3cr
GTRB1415	Electric Guitar Set Up, Lab (fall)	3cr
GTRB1417	Electric Guitar Design (fall)	1cr
GTRB1418	Electric Guitar Construction (spring)	4cr
GTRB1425	Fretwork (fall)	3cr
GTRB1450	Introduction to Finishing (spring)	4cr
Total Credit Requirement - 18

Sabbatical Entry 4

Well let's see, where do I begin on this one? 

Since entry #3 I hopped a flight to Texas for a 10 day trip starting in the capital of Austin.  I had the opportunity to spend three days at the Colling's Guitar Company and would like to thank everyone there for the opportunity.  If you are familiar with their instruments you know it can be argued these are the finest production instruments being made today.  Currently there are four graduates working there and it was great to see them again and have the opportunity to learn from them!

The first day there I had a chance to visit with Steve who oversees all aspects of the Colling's company and Ruth who is head of HR.  It gave them the opportunity to ask about our program and learn more about what we do here in Red Wing.  From there Steve was gracious enough to give me a tour of the factory, different shop areas and an overview of how things are done.  After peppering him with questions along the way (and running into our alumni) I was free to roam the grounds and take a few pictures.  Everyone there was incredibly gracious with their time and telling me anything I wanted to know.  Over the years the vast majority of people I've met in the industry are more than happy to share how they do things and believe there are no "secrets" to their work.  Often folks with this mentality are the most successful people in lutherie.

On the second day I once again was free to roam around, take pictures and ask questions.  Let there be no doubt I took advantage of that opportunity.  I'm not sure how many questions I asked but at the end of the day there were about 650 new pictures on my camera.  Before leaving I made it a point to head back to the finishing area to talk with Joe who completed both diplomas in our guitar program.  We chatted about a few things related to finishing and planned to spend final day  going over the processes he does every day.

A quick little snapshot of acoustic tops with a few production notes included.

Here is an all Koa acoustic that was just removed from the outside mold.  The instrument will stay in an mold from the time the ribs are bent until the top and back are glued on.

There are no shortcuts when prepping an instrument for finish.  Many hours are spent even in a production setting making sure the surface is perfect.  I really like the vacuum fixture holding the mandolin so he can rotate it as necessary.

On my final day there I met up in the finishing department around 9am where Joe was already a few hours into his work day.  He had set aside some instruments to show me some of the finishing steps he does on acoustic guitars.  It was great to see the information he learned in the program being put to use and better yet, having the skills to develop his own approach to what he has learned working at Colling's over the last two years.  One of the most important things to me was seeing the pore filling process he refined so instruments can get through that step in a matter of minutes instead of hours.  To say I was impressed is an understatement.  I took some notes notes and plenty of pictures while he worked and am already prepping some test panels to give it whirl myself.  Just one of the great things in this work is you never stop learning and striving for a better way to get something accomplished.  Well, at least for the folks that know W.O.R.K. is not a radio station.

Here Joe is cleaning up the binding after the excess filler has been removed.  No detail can be missed in this job.

It takes a little practice to get this good at cleaning up purfling.

Amp Building

While in Texas I also spent four days building a guitar amp.  The 4 day workshop wasn't exactly what I expected (based on my interactions with the person offering the course) but the fact remained I finally had the opportunity to build a tube amp.  The gentleman slated to help me was extremely knowledgeable and a great all around guy.  Finally I was able to get my hands on a different set of electronic components and work through each stage of the build.  The amplifier design I chose was about the most intense one they offer for a first time build. There were times I wondered if I'd complete it in time for testing and troubleshooting, but after twenty years of wiring electric guitars those skills kept things moving along quite well.  

Day 1 

The first thing I wanted to do is go through what is in the kit and get it organized.  A little overwhelming at the start but I had help!  I quickly got the tube sockets mounted so I could wire up the filament circuit which provides power to all the tubes.

Apparently a lot of people spend the first day wiring up the filament circuit.  Here I've got it wired by lunch and was feeling pretty good.  I was cautiously optimistic at this point but I could tell the hard work hadn't actually begun.

After lunch I got the transformers, filter capacitors and circuit board mounted.  The filter capacitors hold a dangerous amount of DC voltage but at this point there was no charge in them. 

The project started to look like something when I mounted this circuit board.  It holds the different components for each of the tube circuits.  Little did I know there was a rogue wire!  I wouldn't know I goofed up until the last day....more on this to come.

Here is just one of the spots for grounding components.  It's important to separate the grounds appropriately so one circuit doesn't interfere with another one causing excess noise.

By the end of Day 1 I was feeling good about the progress but still slightly nervous about the time frame because I "didn't know what I didn't know".  Since this was my first amp build I had a sense of how much wiring I'd need to do but couldn't predict how long it would take.

Day 2

The morning began with another round of organizing things for the day and easing into the reality of what's ahead.  There's a brass strip inside the chassis with grounding points for each circuit.  Reality was just beginning to sink in as I reviewed the schematics and pictures included with the amp kit.

It took me a little bit to sort through the resistor values.  We use variable resistors in electric guitars known as potentiometers.  Those are easy because the values are stamped using handy things called "numbers".  Regular resistors have colored bands on them indicating their value and tolerance.  One sneeze at this moment and I would have started over.

Here's a potentiometer with a resistor and capacitor.  I wanted to get as many components wired before mounting the control pots because it's much easier to do outside of the amp chassis.

Since potentiometers have different values it was important to make sure each one going in the amp was sorted out before wiring anything more.  (It isn't just my OCD flaring up I promise)

Now the controls are in the chassis and it's time to get them wired into each circuit.

I started where the guitar enters the amp and worked my way from one end to the other focusing on wiring in the control pots.  Since I really didn't know how far I'd get in one day I'd save the bulk of the tube sockets for later.

Here's more of the first gain stage where we plug into the amp.  I took my time and tried to make sure I knew each connection was correct because I had no idea how much of Day 4 would be available for troubleshooting any problems.

Just working my way across the controls from the input side of the amp towards the output section.

Here is how my brain felt at the end of Day 2.  I'd been wiring all day and then thought about the rest of the tube sockets, all those wires and really began to wonder if I'd get this all done!  Why couldn't I just have built a single-ended Champ design to keep things simple?  Because my mentality has always been to jump in the deep end of the pool to see if I can swim.  Oh, and I wanted an amp with plenty of different "tones".

Day 3

So after an evening studying the schematic some more I felt I had a pretty good game plan for Day 3.  My goal was to have everything wired by the end of the day so Day 4 could be dedicated to troubleshooting the amp, trying different tubes and learning about different techniques for working on an amplifier.  This pictures shows.........more wiring.

Now I'm basically working my way from the input side of the amp to the output side of the amp but working each tube socket and components on the back of the amp trying to make sure I don't miss anything or make any mistakes.

Here is the completed amp.  Little did I know there was that "rogue wire" between two of the boards inside the amp.  This was a mistake I made on the very first morning but fortunately during final inspection we discovered it and got it resolved.

Day 4

There were only a couple of things I wanted to fix the morning of Day 4.  A couple resistors had been on my mind and how I had soldered them to wire extending the length to where they needed to go.  I couldn't get it out of my head and knew it needed to be a physical connection twisted together before soldering it.  I jumped right to it so we could begin troubleshooting any problems. 

Needless to say I was beyond anxious to hear how the amp sounded and was relieved when the power was turned on and nothing exploded.  In fact the amp powered on just fine and after some bias adjustments I was able to hear it for the first time.  It was a deja vu feeling similar to the first time I heard the guitar I made in 1994 as a student in our program!!!  

The amp sounded fantastic and then it was time for some "tube tasting".  I brought several different brands of 6V6 output tubes and a few different options for preamp tubes.  It was a great opportunity to hear the subtle differences from one set of tubes to another.  These days companies buy in bulk from overseas manufacturers.  They test all of the tubes and match them up according to a set of measurements.  While everyone raves about "new old stock" (N.O.S.) tubes that were made in America the reality is supply is dwindling and what's left tend to be tubes other people haven't wanted.  It was important to me that I use what is currently being made to hear the differences and have a sense for how to voice an amp later on.

After playing the amp with many different tube combinations I decided which ones to use and had the bias reset to that specific pair of 6V6's.  The amp was shipped back to Minnesota where it awaits a cabinet and speakers.  Oh, I also have to design and build a cabinet then learn the joys of covering it with material.  It's kind of like having a high performance motor sitting in the garage and needing the car to go along with it.  Just another item on my "to do" list.  Once it's done I'll put some pictures up on the blog and who knows, maybe a sound sample?

I know I took quite a few pictures during on Day 4 but for some reason those have also gone rogue.  I'll be sure to look for them and include it another blog post