Making a guitar with Roy Courtnall

Construction and repair of Classical Guitar and related instruments
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Frousse
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Re: Making a guitar with Roy Courtnall

Post by Frousse » Sun Oct 15, 2017 1:20 am

Thanks for sharing. This is a wonderful journey that you have started. I look forward to more postings and wish you continued progress.

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josswinn
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Re: Making a guitar with Roy Courtnall

Post by josswinn » Sun Oct 15, 2017 8:33 am

Elman Concepcion wrote:
Sun Oct 15, 2017 12:04 am

Hi josswinn
That method of fitting the lattice seems like a lot of work. IMHO.

Just a suggestion.

It would be easier.
If you build the lattice structure off the top.

Once it is build, you can sand it down so all joints are flushed.
i.e. you can over shoot the pockets and then sand any errors back to flush.

Then use fish glue on all the matting surfaces and then place it on the top and use a vacuum table to clamp it over night .
There are other methods of clamping with out a vacuum table but they are not as worry free.
Next, you can use a curved radius sanding block to do some graduations.
I realize you may not have a vacuum table but in future this would save you a lot of time.

Hope that makes sense.

Thanks for this thread It's great !!!
I'm also teaching someone how to build a guitar and I send him here to observe your progress :-)

Cheers
Elman
Thanks for your comments and encouragement, Elman.

Roy and I discussed various ways of assembling the lattice, including as a self-standing unit before attaching to the soundboard; vacuuming etc. but Roy's preferred method is one by one, with individual control in locating and shaping each one before gluing the other struts in place. Getting the lattice and soundboard thickness exactly right seem to be the most critical parts of making this design of guitar. It doesn't really take very long, interspersed through the day while doing other things and time is not a factor for me at the moment.

For my next guitar, I will probably use Go-bar clamps and glue up to nine struts at once. As I make the guitar with Roy, I'm also buying tools, etc. for my next build and so need to make decisions about the set up of my own workshop. The long-reach clamps that Roy uses are very expensive to buy in the UK, available only by import from StewMac.

Cheers,
Joss
Joss Winn

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Re: Making a guitar with Roy Courtnall

Post by josswinn » Sun Oct 15, 2017 9:03 am

khayes wrote:
Sat Oct 14, 2017 9:56 pm
Thanks for posting your process - I look forward to it every week. Looks like you're making the most of a great opportunity.
I'm glad you're finding it interesting, Ken. Initially, I was taking notes and photos solely for my own benefit, but have become mindful to document it so that it will be of interest and benefit to others like me who are building their first guitar.

The next update will be in three weeks' time as I have other obligations over the next couple of weeks which mean we can't work on the guitar.

Cheers
Joss
Joss Winn

JohnH*
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Re: Making a guitar with Roy Courtnall

Post by JohnH* » Sun Oct 15, 2017 4:28 pm

Wow! That is some serious gluing and clamping. I'm really enjoying your pictures and following your progress.
JohnH*
2013 Anders Sterner BRW/Spruce
1989 Yairi CY140 CSA Rosewood/Cedar
"Some places remain unknown because no one has ventured forth. Others remain so because no one has ever come back."

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josswinn
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Re: Making a guitar with Roy Courtnall

Post by josswinn » Sat Nov 04, 2017 8:19 pm

Day 13: (Courtnall book pp.214-7; 237-9) Over the last couple of weeks at home, I finished gluing all the struts of the lattice to the soundboard.

ImageLattice ready for carbon fibre top by Joss Winn, on Flickr

ImageLattice illuminated through the soundboard by Joss Winn, on Flickr

Today, with Roy, I reinforced the spruce struts with carbon fibre, glued kerfed linings to the ribs and made a caul for when clamping the bridge to the soundboard.

First, I prepared the lattice for the carbon fibre. I ensured each strut was cut to the finished length (in hindsight, I should have done this more accurately when actually making the lattice!), and then I scalloped the ends of each strut before rubbing a sanding bar across the whole lattice to ensure that the struts were sufficiently flat to take the carbon fibre strips.

I began by cutting the 1mmx3mm pultruded carbon fibre strips to the correct length for each strut. Then, I masked off two or three struts, mixed a little Araldite Rapid (epoxy adhesive), smeared it on the struts and pushed the strips down, repeatedly checking that they didn't lift away from the spruce:

ImageGluing the carbon fibre with epoxy by Joss Winn, on Flickr

The whole process went well, masking and gluing three struts at a time because I was using a fast setting glue (5 mins). I changed gloves regularly so as not to get epoxy everywhere. Here's the finished lattice:

ImageThe finished lattice with carbon fibre by Joss Winn, on Flickr

Throughout this, I was talking to Roy about the different approaches Luthiers take to making the lattice: balsa or spruce struts; carbon fibre tow or pultruded strips; a carbon fibre/wood sandwich or just a carbon fibre on top, etc. etc. Roy thinks that this design of lattice using spruce and carbon fibre in only one direction, with a 1 to 1.3mm spruce soundboard, produces the "optimum sound" that he and guitarist, Rob Johns, are looking for. To demonstrate this, he played two of his recent guitars at lunch time. They have good strong bass, mid range and treble. As with all guitars, the quest for that little bit extra from the trebles is always ongoing.

Next, I glued the kerfed linings to the soundboard side of each rib, taking care to ensure they were level with the edge of the ribs. Lots of clamps as usual:

ImageClamping the kerfed lining by Joss Winn, on Flickr

Next, I cut and glued the harmonic bars (the end-block in this image is not glued in place):

ImageClamping the harmonic bars by Joss Winn, on Flickr

I will shape the bars next week. Finally, I made a caul for when gluing the bridge to the soundboard. The lattice pattern and the dome of the soundboard meant that this was probably the most difficult thing to undertake this week. I had to shape the piece of wood to the dome of the soundboard and then cut it to fit the lattice. Thankfully, I shouldn't have to make another until I use a different type of strutting design.

ImageMaking a caul for clamping the bridge by Joss Winn, on Flickr

I bought the soundboard home on the solera to cut it more accurate to size with a scalpel and will begin to piece everything together next weekend (the neck is not yet glued to the soundboard in this photo but clamped to the solera for convenient storage and transport home in my car).

ImageSoundboard and neck by Joss Winn, on Flickr

When I'm not in the workshop, I'm trying to learn about the physics of guitar construction. Working at a university, I have access to all of the peer-reviewed scientific literature, although the most useful sources so far have been:

Bader, Rolf (2006) Computational Mechanics of the Classical Guitar
Friederich, Daniel (2013) The classical guitar soundboards and their bracing.
Inta, Ra (2007) The Acoustics of the Steel String Guitar.
Rossing, Thomas (ed.) (2010) The Science of String Instruments (Ch.3 with Graham Caldersmith - also published in Fletcher and Rossing's 'The Physics of Musical Instruments').

I've not yet read Janssen's work, but see that it is summarised in Rossing and Caldersmith's chapter above.
Joss Winn

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josswinn
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Re: Making a guitar with Roy Courtnall

Post by josswinn » Mon Nov 13, 2017 7:47 pm

Day 14 & 15: (Courtnall book pp. 240-252) We've started to assemble the guitar over the last two days.

Yesterday, I reinforced the kerfed linings with a strip of 1mm veneer, giving the ribs more stiffness.

ImageReinforcing the kerfed lining by Joss Winn, on Flickr

I also started to shape the arm rest, taking an off-cut from a rib and cutting it into three 25cm lengths, which were bent, laminated and clamped to the side of the guitar to retain their shape while drying.

ImageLaminating walnut for the arm rest by Joss Winn, on Flickr

I then glued the neck and end block to the soundboard, taking care to get the end block centred and vertical.

ImageGluing the neck and end block to the soundboard by Joss Winn, on Flickr

I then prepared a rib for gluing to the soundboard, first by planing the edges and then sanding it on a sufficiently large sanding board.

ImagePlaning the reinforced lining by Joss Winn, on Flickr

Once that was done, I made corresponding cuts into the lining and the harmonic bars so they fitted together when glued.

ImageChiseling out space for the harmonic bars by Joss Winn, on Flickr

ImageA rib glued to the soundboard by Joss Winn, on Flickr

At the end of the day, I cut the laminated back to shape on the bandsaw and three walnut bars to reinforce it. The ply template on the bar in the photo is shaped to the dome that the back will be forced into when clamped.

ImageShaping the back bars to the dome by Joss Winn, on Flickr

Today, I picked up where I left off and carried on working on the back, shaping each of the bars to a 3mm dome. Once I had finished the longest bar, I used that as the template for the other two, going between my block plane and a shooting board with a small sanding block so as to ensure the bottom of each bar was flat for gluing. Here it is clamped up:

ImageGluing the domed bars to the back by Joss Winn, on Flickr

I cleaned up the glue where it could be seen through the sound hole but left a neat bead where it couldn't be seen in the hope it will give it more strength.

I then turned to the second rib and repeated the process I undertook yesterday of planing and sanding the edge flat, cutting the lining and harmonic bars, making final adjustments to the neck heel wedge and generally getting the whole thing to fit to the plantilla outline.

ImageThe second rib glued and clamped by Joss Winn, on Flickr

That took much of the afternoon, by which time the domed back was dry and I removed the clamps. Here's the result:

ImageThe resulting dome of the back by Joss Winn, on Flickr

Next weekend, I hope to get the back on.
Joss Winn

khayes
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Re: Making a guitar with Roy Courtnall

Post by khayes » Tue Nov 14, 2017 3:32 am

This is the highlight of my day - really interesting to read and see.
Ken

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Re: Making a guitar with Roy Courtnall

Post by TJ2 » Wed Nov 15, 2017 12:46 am

Thanks for sharing your guitar build. It is fun to follow and see the progress.

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josswinn
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Re: Making a guitar with Roy Courtnall

Post by josswinn » Sat Nov 18, 2017 10:06 pm

Day 16: (Courtnall book pp. 253-260; 275-276; 283) Today, I started by reducing the height (depth?) of the ribs so that the back could eventually be glued on. During the week, I had already reduced the height of the ribs at the end block and the foot of the neck and so started the day like this:

ImageReducing the depth of the ribs - first at each end by Joss Winn, on Flickr

I then went around the ribs with a block plane, regularly checking the overall height with a flat board that extended across the end block, neck heel and the ribs. Finally, I lightly sanded them with a board:

ImagePlaning then sanding the depth of the ribs by Joss Winn, on Flickr

I then aligned the centre of the back with the centre line on the heel and end-block and carefully marked the position of the back bars on masking tape I'd stuck on the ribs and also marked where the bars needed cutting down to:

ImageAligning cuts to the ribs and back bars by Joss Winn, on Flickr

Next, having marked where the bars would sit once the back was glued on, I glued the kerfed lining inbetween each of the bar positions, cutting the length of the lining to fit nicely.

ImageGluing kerfed lining with spaces for the back bars by Joss Winn, on Flickr

Once the lining was cut and glued to the ribs, I trimmed the back bars, reinforced the linings with 1mm veneer (see last week's post) and marked, cut and glued a piece of walnut which was used to build up the foot of the neck for gluing to the domed back.

After lunch, we started to work on the fretboard (it's useful to have a couple of things on the go at the same time to turn to while glue is drying). I am using Rocklite which is purchased already pretty flat and square. We discussed various ways of preparing the fretboard. Roy's book shows first planing the tapered shape before cutting fret slots, and gluing it to the neck before cutting slots. However, he told me that it's easier (and less worrying) to cut the slots before gluing to the neck and also cutting them on a square edge fretboard rather than a tapered one, with the tapered edges being made afterwards.

So, we found the best edge and face and using a square, I marked the nut end on all four faces. I then chiselled a groove from the waste side of the line to help position the saw when starting to make the cut. In the image below, you can also see a centre line marked with a knife. Earlier in the week, at home, I thought I'd have a go at marking up the fretboard and foolishly used a knife rather than a pencil to mark the centre line. I realised my mistake and left it until today to see if it could be salvaged. Roy said it was a light cut and can be sanded out. On this first guitar, small mistakes like this are really instructive and keep me grounded.

ImageChiseling a groove for the fret saw by Joss Winn, on Flickr

Turning to the guitar body, the back could now be positioned more or less flat on the ribs. It required a little more work chiseling out the slots in the lining and trimming the length of the bars, eventually achieving a very good fit. With a soft pencil, I drew around the outline of the body on the underside of the shape and cut the back more accurately on the bandsaw.

ImageMarking the final outline of the back by Joss Winn, on Flickr

With the back accurately sawn to shape, I then planed the height of the ribs and lining to fit the dome of the back. This required taking a little more off around the curves of the upper and lower bouts.

I then measured (using the bottom of a vernier caliper), cut and glued six reinforcing struts to the ribs under each of the slots where the back bars fitted.

ImageReinforcing the ribs under each back bar by Joss Winn, on Flickr

With these struts, the reinforced lining, the laminated ribs, and the three flat bars across the domed, laminated back, a strong and rigid body has been created.

Towards the end of the day, I started to plane, chisel and sand the walnut I had glued to the heel of the neck in preparation for gluing to the back.

ImageBuilding up the foot of the neck by Joss Winn, on Flickr

To get the correct level across the dome of the back, I taped off-cuts of thin strips of wood to each upper bout that compensated for the depth of the dome of the back and allowed me to reduce the walnut until it was level with the compensated ribs. The purpose of this was so that with the strips removed, the perimeter of the back lies flat on the ribs and the dome of the back lies flat on the built up neck heel. By this point, it was late in the day so we decided to wait until next week to glue the back on.

The last thing I did was begin to mark the frets out with a sharp blade. Using the measurements from Roy's book, I first made small notches in the fretboard and then double checked them for accuracy. Happy with that, I placed the blade in the notch and pushed a square up to the side of the blade. I then marked the line of the fret along the squared edge.

ImageMarking the frets by Joss Winn, on Flickr

My homework is to finish marking the frets and finish shaping the foot of the neck for gluing the back to.
Joss Winn

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Re: Making a guitar with Roy Courtnall

Post by josswinn » Sun Nov 26, 2017 9:10 pm

Day 17: (Courtnall book pp. 276-7; 289-93) Today, we worked on the armrest, the fretboard and the bridge.

First, I should explain that I wanted to make an armrest both for its apparent utility (avoid dampening and increased comfort for the player) but also for the experience of making one while working with Roy. Roy recently made a magnetic armrest for a guitar but I was flip-flopping between a magnetic one or gluing it to the body. Last weekend, I thought I'd glue it, but after re-reading James Lister and Trevor Gore's comments about magnetic armrests, I finally decided on that approach. This preamble might help explain why last week I glued in the lining and why this week, I started to chisel out slots in the lining for magnets. If I'd decided on a magnetic armrest earlier, I might have cut the lining to accommodate the magnets before gluing it into the body of the guitar. Anyhow, I began the day by cleaning up the bent and 6mm laminated walnut I had prepared on day 14 by planing the edges and trimming the ends. Finally, I rubbed it over a sanding board to ensure there was a nice flat surface to glue the top of the armrest to:

ImagePlaned and sanded armrest attachment by Joss Winn, on Flickr

The 250mm walnut side of the armrest had lost a little of its shape since it was bent and glued - not by much and just at one end - so we figured we'd have to pull it back into line when gluing it to the top part. I'd bought a 4mm sheet of quarter sawn padauk and traced the outline of the body with a sharp pencil. I then cut the outside of it on a bandsaw and finished it with a sanding drum on Roy's pillar drill:

ImageShaping one side of the Padauk armrest by Joss Winn, on Flickr

The inside of the padauk needs cutting to shape too and the walnut will be glued to a 6mm line scribed in from the edge, but that must wait. Next, I wrestled with magnets. I had bought 20 15x3mm N35 rare earth magnets on the advice of Roy who had previously used 12x3mm magnets and felt that stronger ones would be an improvement. My 15mm N35 magnets are rated 30% stronger than 12mm N35 magnets. If you've not handled these magnets you're in for some fun. Given their small size, they are extremely strong and while figuring out how to best employ and situate them in the armrest and in the side of the guitar, the damn things kept flying across the worktop sticking to each other or any other piece of metal. At times it was comical but also painful when they trap the ends of fingers.

Anyway, I took the bent walnut, positioned it where it would eventually sit on the rib and then marked the horizontal distance between each magnet, making sure to avoid the upright struts reinforcing the ribs. Then, taking account of the purfling, the soundboard and the need to have it raised off the soundboard, I marked the vertical position of the magnets, such that they would sit partly embedded in the lining of the guitar. I then drilled 15x3mm holes into the walnut for the magnets to be superglued flush with the surface of the wood.

Next - and this is quite important when handling 16 of these powerful magnets all in close proximity of each other - I paired up 8 sets of magnets so that they stuck to each other and I numbered the top of each pair so as to identify the order of them and because they are identical back and front, so I could glue them into the guitar the correct way around. The last thing I want is to glue them in and then discover that some pairs are attracting and some are repelling. Here they are glued into the walnut with the numbered pairs:

ImagePositioning and numbering the magnets by Joss Winn, on Flickr

I slid the magnets apart (they are too small and strong to prise apart easily) and put the numbered ones well away from the workspace. Next, I took the bent walnut with the embedded magnets and positioned it on the side of the guitar and took a single magnet (number eight) and placed it on the inside of the rib. It grabbed the armrest and allowed me to move the magnet exactly into place along the inside curve of the rib, indicating the position in the lining I needed to cut. There seemed to be no more accurate way of ensuring that each pair of magnets would meet each other in exactly the right place. You can see from the photo below, first where I circled the position of the magnet along the rib and then the corresponding slot that I cut out of the lining for it to drop into. The horizontal pencil line above the magnet was the depth marker that I checked against, chiselling a little out of the lining and dropping the magnet into the slot to see if I'd hit the right depth.

ImageSlots are cut into the lining for the armrest magnets by Joss Winn, on Flickr

The first slot was a really tedious piece of work, using a 1 and 2mm chisel to carefully remove the wood. The answer is to make plenty of room for the magnet, taking out 4mm for the depth of the magnet which allows easier access for the chisel. The next 7 slots should be easier and faster and I'll do them over the next week. We tested whether the first slot had been successfully positioned, allowing the two magnets to find each other on the rib and sure enough, the walnut naturally found its place with its top edge raised above the soundboard. You'd think it was magic:

ImageThe line of the arm rest with one magnet fitted by Joss Winn, on Flickr

I will repeat this for each magnet, making sure that each is correctly positioned before moving on to the next. Making the armrest has been a lot of fun so far - time consuming but a great problem-solving exercise. Fingers-crossed it will work well. I have a nagging concern that using 8 magnets might make it difficult to actually remove from the guitar, although sliding it up and off should be OK. Also, I wonder if there are there health risks having such powerful magnets next to the player's body?

Next, we turned to the fretboard. I stuck masking tape down the two sides to make it easier and more visible to mark out. Then, finding the centre line I had previously marked I used dividers to mark the width at the nut and the 12th fret. I scored a line between each and pulled off the outside piece of tape to reveal the taper I need to achieve. After taking much of it off with the bandsaw, I planed it exactly to the line making sure the edge of the fretboard was square with the face:

ImagePlaning the fretboard to its finished dimensions by Joss Winn, on Flickr

Putting the fretboard to one side, we spent the rest of the day working on the bridge(s). I'm wondering whether to use Padauk or Madagascan Rosewood. The binding of the guitar will be Padauk, as is half of the armrest. I had assumed the padauk would have lower mass than the rosewood, but the padauk I have is 822kg/m3 and the rosewood is 819kg/m3 so there seems to be no benefit there. Anyway, I carefully cut both bridge blanks to the desired length and then planed it square. The rosewood had a more glassy feel to it when being planed and smelled great.

ImageTwo planed bridge blanks by Joss Winn, on Flickr

As I was doing this, Roy was making a sanding block that was shaped to the dome of the soundboard. I then took a scraper and started to shape one side of the rosewood to the dome. When I was nearly there, I marked the centre of the bridge and the centre of the domed sanding block and then sanded back and forth, keeping both lines aligned:

ImageShaping the bridge blank on a domed sanding block by Joss Winn, on Flickr

It didn't take much to get it to the desired shape of the soundboard:

ImageThe shaped bridge blank by Joss Winn, on Flickr

Next, I had to reduce the height of the bridge to 9mm, using Roy's 'bridge jig':

ImageThe bridge jig with a 9mm top layer by Joss Winn, on Flickr

The top piece of ply for the jig is 9mm and a piece of veneer taped in the bottom of the 'window' is the height of the dome. I marked a line along the length of the wood and planed it to the line, tried it in the jig and shaved a little more off so that a ruler could skim across both the jig and the rosewood. As usual, it was a case of making sure the face was planed level and flat.

ImageThe bridge is planed to 9mm height by Joss Winn, on Flickr

I then marked the 'wings' of the bridge and the location of the string holes. I only needed six holes as I will use 'string beads', Roy's current preferred method. Using a 1.5mm drill bit, I carefully drilled the holes, using masking tape on the drill bit to indicate when I'd reached the desired depth:

ImageThe string holes are marked and drilled with a 1.5mm bit by Joss Winn, on Flickr

I then cut and chiseled the wings of the bridge...

ImageThe 40mm bridge 'wings' are chiseled out by Joss Winn, on Flickr

... and routed the slots:

ImageThe slots are routed by Joss Winn, on Flickr

Here's where we finished up today: The basic shape of the bridge is complete and will take strings. I will clean it up next week:

ImageThe bridge has been cut and routed and ready for finishing by Joss Winn, on Flickr

Comments on magnetic arms rests welcome... :-)
Joss Winn

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Re: Making a guitar with Roy Courtnall

Post by lamanoditrento » Sun Nov 26, 2017 11:31 pm

I have never seen the veneer over the kerfed lining, that is a really interesting idea!

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Re: Making a guitar with Roy Courtnall

Post by SteveL123 » Sun Nov 26, 2017 11:40 pm

Hey Josswinn, I've been following this great thread with the awesome pics!

In regards to "Last weekend, I thought I'd glue it, but after re-reading James Lister and Trevor Gore's comments about magnetic armrests, I finally decided on that approach."

Can you supply a link to those comments? Have you weighed the magnets? Does the added weight change the sound?

Edit: Why was N35 magnets chosen? Why not N52, which is stronger?

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Re: Making a guitar with Roy Courtnall

Post by josswinn » Mon Nov 27, 2017 6:54 am

The thread I was referring to is this one.

I chose N35 because they are easily available in 15x3mm size. I think N52 start at 20mm and that's quite large for working on a curved surface.

I'll weigh the magnets later - they are not especially heavy but I suppose the added mass in the lining will have some kind of effect, but whether it's discernible to the ear - I don't know at this stage. No-one using them on this forum has suggested any appreciable difference due to the mass. The main concern is to improve the sound by keeping the arm off the sound board.

Edit: each 15x3mm magnet weighs 0.48g
Last edited by josswinn on Mon Nov 27, 2017 7:46 am, edited 1 time in total.
Joss Winn

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Re: Making a guitar with Roy Courtnall

Post by josswinn » Mon Nov 27, 2017 7:12 am

Roy has suggested I point out that: "a curved rest laminated from multiple layers of 1mm veneer {as I did}, retained its shape completely, whereas your 3 layers of 2mm walnut moved at the end(s). This is why curved furniture is multi layered. We could have used 1mm thick veneer with a final 0.6 walnut veneer for colour matching, would have given a more perfectly shaped curve without needing the bending iron."

Here's an image of how Roy attached four magnets on a recent guitar, "showing stages of fitting, finally covering with veneer of wood. Also see the 1mm thick veneer covering almost all kerfed lining making it very rigid."

ImageRoy's arm rest magnets by Joss Winn, on Flickr

Rather than go into the lining, the side of Roy's arm rest extends deeper into the body of the guitar than mine.

And here's an image of my armrest with holes drilled but no magnets. I first drew a red line across the magnets when pairing them but found that wasn't adequate to distinguish the pairs, so resorted to numbering them:

ImageHoles drilled in the armrest for magnets by Joss Winn, on Flickr
Joss Winn

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Re: Making a guitar with Roy Courtnall

Post by josswinn » Mon Nov 27, 2017 8:45 am

Here's a photo that shows a recent guitar made by Roy, with armrest and Rosette string beads:

ImageClassical guitar by Roy Courtnall (2017). Lattice struts, armrest, string beads. by Joss Winn, on Flickr

This page on Roy's website also explains advantages of beads and the lattice in general.

Reflecting on the added weight of the magnetic armrest, Roy emailed me this morning and said: "weight added by magnets seems unimportant. In general, a lattice design seems to render all the discussions about body resonance irrelevant. We do end up with something between Gsharp and A. That is inevitable given the thin, tight top and the rigid body. But there is no sign of any problems / weaknesses with notes around these pitches. Body res. seems more of an issue with low , 'thuddy' guitars, where the bass can suffer with a low res. Anyway, this is Rob's and my conclusion after six lattices."
Joss Winn

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