Making a guitar with Roy Courtnall

Construction and repair of Classical Guitar and related instruments
User avatar
Frousse
Posts: 321
Joined: Sat Jan 17, 2015 8:02 pm

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.

User avatar
josswinn
Posts: 27
Joined: Mon Jul 10, 2017 9:20 pm
Location: Lincoln, UK

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

User avatar
josswinn
Posts: 27
Joined: Mon Jul 10, 2017 9:20 pm
Location: Lincoln, UK

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

JohnH*
Posts: 307
Joined: Sun Feb 07, 2010 6:47 pm
Location: Raleigh, NC

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
1991 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."

User avatar
josswinn
Posts: 27
Joined: Mon Jul 10, 2017 9:20 pm
Location: Lincoln, UK

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.

User avatar
josswinn
Posts: 27
Joined: Mon Jul 10, 2017 9:20 pm
Location: Lincoln, UK

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.

khayes
Posts: 1237
Joined: Fri Sep 22, 2006 7:29 pm
Location: Middle Tennessee

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

TJ2
Posts: 38
Joined: Fri Dec 19, 2014 9:11 pm
Location: Oregon

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.

User avatar
josswinn
Posts: 27
Joined: Mon Jul 10, 2017 9:20 pm
Location: Lincoln, UK

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.

Return to “Luthiers”