Post by R the F on Nov 16, 2016 22:15:21 GMT
(There's nothing very vital to read here that won't be covered again when I actually get round to building the guitar; it's just a way for me to formalise my preliminary thoughts and save them for future reference in a handy place.)
Anyone who’s ever followed one of my builds will realise that I generally set off with only the vaguest idea of where I’m going. I may have done a lot of thinking about one particular aspect of things - often it has to do with the bracing pattern or related structural matters – but I certainly can’t produce the classic photo of the materials I am going to use and give a clear account of how I am going to put them together. During the build I usually stop to build a jig of some kind or change my mind about how something is going to be done or, indeed, what it is I am going to do; in short, I tend to work on the hoof. This may be good fun and jolly entertaining but it is certainly not the most efficient or business-like way of going about things (as all the other luthiers on here discovered a long time ago). With this in mind I have decided to spend a little time in preparation before launching into another instrument build. This will involve answering a lot of questions before I start and here are the answers to some of those questions which occur to me as I write – in no particular order:
It’s going to be a guitar with 6 strings. Here are some dimensions:
Scale: 645mm
Lower bout width: 388mm
Upper bout width: 290mm
Body Length: 495.7mm
Body depth: 125-100mm
Total guitar length: 1481.7mm
Nut: 45.25mm (not sure how I arrived at that)
Fret 12: 56.33mm
String spread at saddle: c. 58mm
Arch of back radius: 1182.5mm
Radius of sound-board corrugation: 156mm
Radius of finger-board: 304 – 404mm
It’ll have a round hole (101mm in diameter) and will have the same body shape as my previous instruments. I will revert to the Beefy Bryn hole position, which is very high on the body allowing as much uninterrupted soundboard area as possible surrounding the bridge. The neck will again join at the 13th fret, which seems to me to allow a good compromise between bridge placement and access to upper frets. However, there will be no cutaway; Keith doesn’t like them and his guitar-playing impresses me even if I’m not that keen on Ralph McTell having listened intently to Streets of London a sickening number of times with innumerable foreign students during my middle years. Sorry, Sir, but you’ll never show me anything to make me change my mind. So no cutaway this time but there will be one of those slopy thingies that Francis and Rosie have used recently because some people do deserve/demand access to plinky notes.
I like the headstock I have used on the last two guitars with a slight bulging down the sides; using straight sides tends to produce an optical illusion of a concave curve which I don’t particularly like. I also like the ajlucas designed omphalos (pretentious word that but implies the centre of the world as well as the navel - in Greek - and that’s always appealed to me) giving access to the truss-rod, so that’s staying. And, talking of headstocks, I adore Adrian’s and RosieTGC ’s designs so, in a pathetic echo of their beauties, there’s going to be a good thick facing of laburnum lined with maple veneer but both will be trimmed back at the edges like this:
to reveal the mahogany beneath. It’s my attempt to add a bit of class – pronounced /klæs/ rather than /klα:s/ - to the design. The back of the headstock will, as usual, not be plated.
Talking of omphaloi (even more pretentious), this guitar’s going to have another one a little nearer its normal central position on the body (but round the back):
This one will afford everyday access to the neck-angle adjuster. I’ve already put in a good few hours sorting out the way this is going to work (apologies to Howe-Orme, nkforster and, indeed, francis for not keeping it simple) but I think it will be pretty straightforward from the point of view of the player. You stick a thin screwdriver or similar into the navel and locate the hole in the side of the bolt-head – technically called a “capstan screw” I believe; then you turn the bolt a little – one way to move the head back slightly and the other to move it up, thus helping to change the action at the 12th fret – though, of course, you may need to do this in conjunction with truss-rod adjustment and saddle height adjustment. The complicated bit involves two bolt heads accessible only via the sound-hole which lie just beneath the soundboard under the top end of the fretboard. These should never need touching but can be used to adjust the string length and thus the intonation. They in fact move the pivot point (and the whole neck) away from or closer to the body of the guitar. They are really there to make it more convenient for me, the maker, to adjust the initial set-up of intonation but, if the everyday navel adjuster is used to change the action to an extreme position, this could possibly result in a lengthening or shortening of the strings by up to 0.35mm, though the guitar would already be unplayable by normal means at these extremes. Normal adjustment to suit preferred 12th fret action should not exceed 0.15mm (which is 0.023% of string length ≈ nothing at all). For those who care, here are some diagrams of the way the adjustment is arranged internally:
None of which explains why I want an adjustable neck in the first place. It’s because I would like to avoid the need for the neck angle to depend so much on my precise placement of the slots in the sides of my neck-block. I suppose the obvious solution would seem to be to use a bolt-on neck. But if you’re going to bolt the neck on, you might as well incorporate some convenient (externally accessible) means of adjustment, which is what I’ve done. To be honest, it also stems from an interest in Howe-Orme guitars and in nkforster ’s discovery that a neck which makes only a minimal three-point contact with the body does not seem to affect the quality of the sound of the guitar. I could have copied the Howe-Orme arrangement but preferred to have the pivot closer to the strings to avoid potential problems with intonation so I’ve exchanged the positions of the pivot and the adjuster (as Francis does on his adjustable necks). It’s also to avoid putting off too many potential players with that terrifying “gap” between body and neck. The gap is still there, of course; it’s just that you can’t see it! I think I’ve also overcome the problem with players who insist on yanking a bit of bend out of the neck in that the capstan bolt-head is “captive” between two brass plates.
The next question concerns recent experience with balancing structural strength against the responsiveness of the soundboard. Most recently, I reinforced the centre of the soundboard by incorporating a thin surface layer of hardwood running from the sound-hole to the bridge and beyond. This seems to have worked quite well though some notes on this guitar are not as good as others and this could be related to the unusual soundboard structure (or, of course, to a number of other things such as not tuning the top and bottom plates to match). As an alternative to this method of strengthening the spine of the guitar, I have decided this time to copy Howe-Orme and use what nkforster calls a cylinder soundboard i.e. one with a prominent arch or (single) corrugation down the middle with flat soundboard to either side. This should effectively stiffen the spine while leaving a surrounding area of more responsive soundboard. Nigel also suggests that this allows the soundboard to be considerably thinner than usual so I will take the thickness down to under 2mm (if I dare). I actually considered a few variations on this theme with more but shallower corrugations but ended up back where Howe-Orme started:
The combination of the arched spine to the soundboard and the adjustable neck mean that the end of the fretboard has to float above the surface of the soundboard much in the same way as it would on a carved archtop guitar. Fortunately, I love this effect.
To complete the details of the box or body: the sides will be laminated from 5 layers of constructional veneer (approximately 7.5mm thick alternating three layers with longitudinal grain and two with lateral); the back will be laminated with 2 layers of constructional veneer with a centre join on the outside and a three-piece interior (as on the last two guitars). The back will be conspicuously arched side to side as in previous builds to help with rigidity and also to help narrow the guitar side for the sake of the player’s comfort. The bindings/purfling will be kept simple: a black/white line with a nice rounded lump of something pretty and brown right on the corner. The sound-hole rosette will be raised and rounded laburnum to echo the bridge design. Although this may add extra weight to the soundboard, it will obviate the need for so much strengthening around the underside of the soundboard adjacent to the sound-hole. The port in the upper bout side will be lined with dark/light lines of veneer. The heel-cap will be laburnum with a band of maple veneer.
Of course, all of this should have started with a list of materials to be used. Well, here goes. The soundboard and all bracing (apart from oak flying buttresses) will be 80-year-old douglas fir. The back and sides will be sapele. The neck will be of 200-year-old mahogany with bands of maple and dark veneer down the middle. The fretboard and bridge will be laburnum. The headstock facing will be laburnum. The fret-markers will be camel bone. The machine-heads will be Axes-r-us Aluminium Lockers. The frets and saddle will be Jesscar Evo Gold FW47104 (as ever). There will be a two-way truss-rod with access through the headstock (but no cover) and two strips of carbon fibre stiffening, one either side of the truss-rod. The neck adjusting mechanism will be made of stainless steel (capstan) bolts pressing on brass plates with stainless steel cross-dowels (barrel nuts).
The bracing of the soundboard will be only slightly modified from my most recent efforts, the changes being only for entirely practical reasons; if there is to be a central ridge/corrugation/lump, something has to show it what shape it is supposed to be so I have added a few transverse braces and bent a couple of main braces to accommodate them:
(I should point out that what you can see there only looks like a UTB!). There is a question of whether the ridge of the braces which cross the corrugation should be parallel to the base (maintaining a near uniform height) or whether they should “bridge” the valley. I favour the former since the effect would be considerably lighter and more flexible. Since they do bend quite acutely as they move into and out this valley or corrugation, I am also considering the need to laminate the braces horizontally so that they are more compliant. The back will be ladder-braced as before.
People from the local villages have unfortunately been flocking to my door to have their furniture mended in recent weeks so I'm not sure when the next project might start. By the time it does I may have changed my mind entirely.
Rob
Anyone who’s ever followed one of my builds will realise that I generally set off with only the vaguest idea of where I’m going. I may have done a lot of thinking about one particular aspect of things - often it has to do with the bracing pattern or related structural matters – but I certainly can’t produce the classic photo of the materials I am going to use and give a clear account of how I am going to put them together. During the build I usually stop to build a jig of some kind or change my mind about how something is going to be done or, indeed, what it is I am going to do; in short, I tend to work on the hoof. This may be good fun and jolly entertaining but it is certainly not the most efficient or business-like way of going about things (as all the other luthiers on here discovered a long time ago). With this in mind I have decided to spend a little time in preparation before launching into another instrument build. This will involve answering a lot of questions before I start and here are the answers to some of those questions which occur to me as I write – in no particular order:
It’s going to be a guitar with 6 strings. Here are some dimensions:
Scale: 645mm
Lower bout width: 388mm
Upper bout width: 290mm
Body Length: 495.7mm
Body depth: 125-100mm
Total guitar length: 1481.7mm
Nut: 45.25mm (not sure how I arrived at that)
Fret 12: 56.33mm
String spread at saddle: c. 58mm
Arch of back radius: 1182.5mm
Radius of sound-board corrugation: 156mm
Radius of finger-board: 304 – 404mm
It’ll have a round hole (101mm in diameter) and will have the same body shape as my previous instruments. I will revert to the Beefy Bryn hole position, which is very high on the body allowing as much uninterrupted soundboard area as possible surrounding the bridge. The neck will again join at the 13th fret, which seems to me to allow a good compromise between bridge placement and access to upper frets. However, there will be no cutaway; Keith doesn’t like them and his guitar-playing impresses me even if I’m not that keen on Ralph McTell having listened intently to Streets of London a sickening number of times with innumerable foreign students during my middle years. Sorry, Sir, but you’ll never show me anything to make me change my mind. So no cutaway this time but there will be one of those slopy thingies that Francis and Rosie have used recently because some people do deserve/demand access to plinky notes.
I like the headstock I have used on the last two guitars with a slight bulging down the sides; using straight sides tends to produce an optical illusion of a concave curve which I don’t particularly like. I also like the ajlucas designed omphalos (pretentious word that but implies the centre of the world as well as the navel - in Greek - and that’s always appealed to me) giving access to the truss-rod, so that’s staying. And, talking of headstocks, I adore Adrian’s and RosieTGC ’s designs so, in a pathetic echo of their beauties, there’s going to be a good thick facing of laburnum lined with maple veneer but both will be trimmed back at the edges like this:
to reveal the mahogany beneath. It’s my attempt to add a bit of class – pronounced /klæs/ rather than /klα:s/ - to the design. The back of the headstock will, as usual, not be plated.
Talking of omphaloi (even more pretentious), this guitar’s going to have another one a little nearer its normal central position on the body (but round the back):
This one will afford everyday access to the neck-angle adjuster. I’ve already put in a good few hours sorting out the way this is going to work (apologies to Howe-Orme, nkforster and, indeed, francis for not keeping it simple) but I think it will be pretty straightforward from the point of view of the player. You stick a thin screwdriver or similar into the navel and locate the hole in the side of the bolt-head – technically called a “capstan screw” I believe; then you turn the bolt a little – one way to move the head back slightly and the other to move it up, thus helping to change the action at the 12th fret – though, of course, you may need to do this in conjunction with truss-rod adjustment and saddle height adjustment. The complicated bit involves two bolt heads accessible only via the sound-hole which lie just beneath the soundboard under the top end of the fretboard. These should never need touching but can be used to adjust the string length and thus the intonation. They in fact move the pivot point (and the whole neck) away from or closer to the body of the guitar. They are really there to make it more convenient for me, the maker, to adjust the initial set-up of intonation but, if the everyday navel adjuster is used to change the action to an extreme position, this could possibly result in a lengthening or shortening of the strings by up to 0.35mm, though the guitar would already be unplayable by normal means at these extremes. Normal adjustment to suit preferred 12th fret action should not exceed 0.15mm (which is 0.023% of string length ≈ nothing at all). For those who care, here are some diagrams of the way the adjustment is arranged internally:
None of which explains why I want an adjustable neck in the first place. It’s because I would like to avoid the need for the neck angle to depend so much on my precise placement of the slots in the sides of my neck-block. I suppose the obvious solution would seem to be to use a bolt-on neck. But if you’re going to bolt the neck on, you might as well incorporate some convenient (externally accessible) means of adjustment, which is what I’ve done. To be honest, it also stems from an interest in Howe-Orme guitars and in nkforster ’s discovery that a neck which makes only a minimal three-point contact with the body does not seem to affect the quality of the sound of the guitar. I could have copied the Howe-Orme arrangement but preferred to have the pivot closer to the strings to avoid potential problems with intonation so I’ve exchanged the positions of the pivot and the adjuster (as Francis does on his adjustable necks). It’s also to avoid putting off too many potential players with that terrifying “gap” between body and neck. The gap is still there, of course; it’s just that you can’t see it! I think I’ve also overcome the problem with players who insist on yanking a bit of bend out of the neck in that the capstan bolt-head is “captive” between two brass plates.
The next question concerns recent experience with balancing structural strength against the responsiveness of the soundboard. Most recently, I reinforced the centre of the soundboard by incorporating a thin surface layer of hardwood running from the sound-hole to the bridge and beyond. This seems to have worked quite well though some notes on this guitar are not as good as others and this could be related to the unusual soundboard structure (or, of course, to a number of other things such as not tuning the top and bottom plates to match). As an alternative to this method of strengthening the spine of the guitar, I have decided this time to copy Howe-Orme and use what nkforster calls a cylinder soundboard i.e. one with a prominent arch or (single) corrugation down the middle with flat soundboard to either side. This should effectively stiffen the spine while leaving a surrounding area of more responsive soundboard. Nigel also suggests that this allows the soundboard to be considerably thinner than usual so I will take the thickness down to under 2mm (if I dare). I actually considered a few variations on this theme with more but shallower corrugations but ended up back where Howe-Orme started:
The combination of the arched spine to the soundboard and the adjustable neck mean that the end of the fretboard has to float above the surface of the soundboard much in the same way as it would on a carved archtop guitar. Fortunately, I love this effect.
To complete the details of the box or body: the sides will be laminated from 5 layers of constructional veneer (approximately 7.5mm thick alternating three layers with longitudinal grain and two with lateral); the back will be laminated with 2 layers of constructional veneer with a centre join on the outside and a three-piece interior (as on the last two guitars). The back will be conspicuously arched side to side as in previous builds to help with rigidity and also to help narrow the guitar side for the sake of the player’s comfort. The bindings/purfling will be kept simple: a black/white line with a nice rounded lump of something pretty and brown right on the corner. The sound-hole rosette will be raised and rounded laburnum to echo the bridge design. Although this may add extra weight to the soundboard, it will obviate the need for so much strengthening around the underside of the soundboard adjacent to the sound-hole. The port in the upper bout side will be lined with dark/light lines of veneer. The heel-cap will be laburnum with a band of maple veneer.
Of course, all of this should have started with a list of materials to be used. Well, here goes. The soundboard and all bracing (apart from oak flying buttresses) will be 80-year-old douglas fir. The back and sides will be sapele. The neck will be of 200-year-old mahogany with bands of maple and dark veneer down the middle. The fretboard and bridge will be laburnum. The headstock facing will be laburnum. The fret-markers will be camel bone. The machine-heads will be Axes-r-us Aluminium Lockers. The frets and saddle will be Jesscar Evo Gold FW47104 (as ever). There will be a two-way truss-rod with access through the headstock (but no cover) and two strips of carbon fibre stiffening, one either side of the truss-rod. The neck adjusting mechanism will be made of stainless steel (capstan) bolts pressing on brass plates with stainless steel cross-dowels (barrel nuts).
The bracing of the soundboard will be only slightly modified from my most recent efforts, the changes being only for entirely practical reasons; if there is to be a central ridge/corrugation/lump, something has to show it what shape it is supposed to be so I have added a few transverse braces and bent a couple of main braces to accommodate them:
(I should point out that what you can see there only looks like a UTB!). There is a question of whether the ridge of the braces which cross the corrugation should be parallel to the base (maintaining a near uniform height) or whether they should “bridge” the valley. I favour the former since the effect would be considerably lighter and more flexible. Since they do bend quite acutely as they move into and out this valley or corrugation, I am also considering the need to laminate the braces horizontally so that they are more compliant. The back will be ladder-braced as before.
People from the local villages have unfortunately been flocking to my door to have their furniture mended in recent weeks so I'm not sure when the next project might start. By the time it does I may have changed my mind entirely.
Rob
.... Rob just likes to keep people guessing 
Jo whoever he is.
