Post by R the F on Jun 5, 2015 20:41:39 GMT
Having completed my prototype, I decided to get straight on to building a couple of guitars together/in parallel, each of which will be almost but not quite the same as the “Almost built first build” guitar. With luck the differences will be improvements but we’ll have to see about that – and things might change as I along; they usually do. That thread began at the end and this one begins right at the beginning and will, I hope, show some of the difficulties we ordinary mortals have in making our first guitars, especially when you’re a poor amateur chap who tries to live within his means and can’t really justify the expense of too many visits to the Stewmac website.
So here we go, warts and all.
On 17th May I bought 4 likely looking doors locally for £20 (£5 each, buyer collects). Into the back of the Golf and then home to be stacked away and butchered when necessary. Here’s the first in mid-butchery – note the handsaw and sweaty patches:
These instantly recognisable doors are from the 1930s and are generally made of quarter-sawn Douglas Fir. This may not be the best material for a soundboard but it’ll do me because it’s a lovely colour and not a knot in sight. Our house is full of them:
but we need those to fill the holes so I buy them on ebay for building guitars. They don’t yield as much timber as you might think because they’re full of finger-thick dowels but you can skim off quite a lot if you’re careful. Here is what I did to one stile with my trusty table saw cunningly lined up with the growth rings – not a job for the shaky of hand:
I’ve taken 2 strips for heftier braces (c. 7mm), 2 for lighter braces(c 5mm) and the rest (just under 2mm thick) for laminating the linings. I follow colins religiously on these so need similar strips of mahogany and these come from a table leg circa 1830, I reckon. (This table cost £25 and yielded three large leaves as well as the legs, though I had to travel 30 miles to pick it up). Here’s a similar one which is on ebay now:
:
And this is the leg of mine being sliced into rashers – thin-kerf blade to save on wastage (1 browny point):
Of course, these have to be thinned a little before laminating and I do this in my home-made sander-thicknesser – (plans found on-line):
Still following colins’s method, I thin the Douglas Fir and the mahogany to 1.25mm and then laminate them in cork-lined formers:
Now I’ve never been very pure in my methods so these have been glued with Cascamite (wash your mouth out with soap and water) because it gives you plenty of open time and they come out jolly stiff, which is the aim after all.
[Cascamite, for those who don’t know and want to, is in fact a white powder 2-part glue (urea-formaldehyde) which is only activated when you add water. It then sets chemically into whatever space it is filling. It gives ample time to sort things out before it goes off but you don’t have to leave it for 12 hours before touching the joint/repair. It doesn’t smell and isn’t even bothered by water. You can even colour it to match surrounding wood. Perfect…. for irreversible work - though it is reversible with a file or a chisel or drill - and you would have to be rather strange to want to reverse the gluing of these laminates!]
Nevertheless, I am reforming and the fish glue arrived just in time to do the last set – still cramped up at present so more of that later. [By the way, fish glue doesn’t smell horrible: when I was young (in the make-do 50s) we had a tube of “Seccotine” with a screw-eye bunging up the end in the sideboard drawer which was used for all our daily sticking needs - paper, card, leather and probably plates, too. And that’s what fish-glue smells like – a bit like hospitals or laboratories]. Now you have to remember that for 2 guitars you need 2 left top linings and 2 left bottom and 2 right top and 2 right bottom, which makes 8 gluing sessions. Furthermore, I don’t seem to be able get away without bending each component on a bending iron before putting them into the former (fairly tight bends on this guitar) and that’s a total of 4 x 8 = 32 bending sessions. All good practice, I suppose.
The other problem I have is that there is a 1775mm radius arch across the top of the guitar and a 1185mm radius arch across the back. This means that the sides become considerably deeper and shallower as they move in and out and the linings have to follow these curves, which look like this:
While these will be sanded to their final contour after being attached to the sides, they have to be cut approximately to shape before being attached. Since laminating them in their final form is quite tricky, I’ve found it best to draw in the shape on the inside laminate so that they can be glued with straight edges and cut to shapes after being removed from the forms. Here are a couple of pictures which may explain what the hell I am talking about:
Meanwhile, I am thinking about modifying the bracing of the soundboard. Some expressed doubts about the lack of a UTB (Upper Transverse Brace or Ugly Thick Bit – take your choice) in the design for my prototype:
"In conventional guitar construction without other means of support such as flying buttress bracing it's main job is to stop the end of the fingerboard disappearing into the box and the rest of the guitar top collapsing into the sound hole under string tension. But that could be a false rumour spread by luthiers - you'll find out. "
and
"I'm sorry, you decided on your first guitar to leave out the UTBs because you didn't understand what it did and it was a bit ugly! Have you noticed that every guitar out there has them, steel strings, classicals. It is a major structural element of the guitar which helps stop the thing folding in half.
"
and time may well prove them right to have worried. However, I actually think my death-defying diamond design provides the “support such as flying buttress bracing” that the former advocates and, if I may be so bold, overdoes it. I think the rigidity built into the prototype almost stifles its ability to sing out so I am going to try to lighten it up a little this time. So here below are designs of the prototype bracing followed by the slightly changed bracing I’m planning for the two under construction:
The one on the right lightens some of the secondary bracing but I will also carve away a little more of the “diamond” to see how much I can get away with. The middle version resulted from a comment made by a violin-maker friend of mine who says “With violins, some people have tried making the strongest point of the bass bar [this is a brace] right under the bridge and this isn't helpful - you need the driving force away from the centre or strongest point, just like bowing a string in its middle has less effect than bowing nearer the bridge.” I wasn’t brave enough to shift the cross-over to the side and make the whole thing asymmetrical so I took an easier option and extended the diamond past the bridge area. Whether violins can teacher guitars anything is uncertain since the energy input is continuous when bowing a violin as opposed to a little pluck but it’s worth a try.
Hope you don’t find all this a bit excessive but I’ve got no one else to talk to about it!
So here we go, warts and all.
On 17th May I bought 4 likely looking doors locally for £20 (£5 each, buyer collects). Into the back of the Golf and then home to be stacked away and butchered when necessary. Here’s the first in mid-butchery – note the handsaw and sweaty patches:
These instantly recognisable doors are from the 1930s and are generally made of quarter-sawn Douglas Fir. This may not be the best material for a soundboard but it’ll do me because it’s a lovely colour and not a knot in sight. Our house is full of them:
but we need those to fill the holes so I buy them on ebay for building guitars. They don’t yield as much timber as you might think because they’re full of finger-thick dowels but you can skim off quite a lot if you’re careful. Here is what I did to one stile with my trusty table saw cunningly lined up with the growth rings – not a job for the shaky of hand:
I’ve taken 2 strips for heftier braces (c. 7mm), 2 for lighter braces(c 5mm) and the rest (just under 2mm thick) for laminating the linings. I follow colins religiously on these so need similar strips of mahogany and these come from a table leg circa 1830, I reckon. (This table cost £25 and yielded three large leaves as well as the legs, though I had to travel 30 miles to pick it up). Here’s a similar one which is on ebay now:
:
And this is the leg of mine being sliced into rashers – thin-kerf blade to save on wastage (1 browny point):
Of course, these have to be thinned a little before laminating and I do this in my home-made sander-thicknesser – (plans found on-line):
Still following colins’s method, I thin the Douglas Fir and the mahogany to 1.25mm and then laminate them in cork-lined formers:
Now I’ve never been very pure in my methods so these have been glued with Cascamite (wash your mouth out with soap and water) because it gives you plenty of open time and they come out jolly stiff, which is the aim after all.
[Cascamite, for those who don’t know and want to, is in fact a white powder 2-part glue (urea-formaldehyde) which is only activated when you add water. It then sets chemically into whatever space it is filling. It gives ample time to sort things out before it goes off but you don’t have to leave it for 12 hours before touching the joint/repair. It doesn’t smell and isn’t even bothered by water. You can even colour it to match surrounding wood. Perfect…. for irreversible work - though it is reversible with a file or a chisel or drill - and you would have to be rather strange to want to reverse the gluing of these laminates!]
Nevertheless, I am reforming and the fish glue arrived just in time to do the last set – still cramped up at present so more of that later. [By the way, fish glue doesn’t smell horrible: when I was young (in the make-do 50s) we had a tube of “Seccotine” with a screw-eye bunging up the end in the sideboard drawer which was used for all our daily sticking needs - paper, card, leather and probably plates, too. And that’s what fish-glue smells like – a bit like hospitals or laboratories]. Now you have to remember that for 2 guitars you need 2 left top linings and 2 left bottom and 2 right top and 2 right bottom, which makes 8 gluing sessions. Furthermore, I don’t seem to be able get away without bending each component on a bending iron before putting them into the former (fairly tight bends on this guitar) and that’s a total of 4 x 8 = 32 bending sessions. All good practice, I suppose.
The other problem I have is that there is a 1775mm radius arch across the top of the guitar and a 1185mm radius arch across the back. This means that the sides become considerably deeper and shallower as they move in and out and the linings have to follow these curves, which look like this:
While these will be sanded to their final contour after being attached to the sides, they have to be cut approximately to shape before being attached. Since laminating them in their final form is quite tricky, I’ve found it best to draw in the shape on the inside laminate so that they can be glued with straight edges and cut to shapes after being removed from the forms. Here are a couple of pictures which may explain what the hell I am talking about:
Meanwhile, I am thinking about modifying the bracing of the soundboard. Some expressed doubts about the lack of a UTB (Upper Transverse Brace or Ugly Thick Bit – take your choice) in the design for my prototype:
"In conventional guitar construction without other means of support such as flying buttress bracing it's main job is to stop the end of the fingerboard disappearing into the box and the rest of the guitar top collapsing into the sound hole under string tension. But that could be a false rumour spread by luthiers - you'll find out. "
and
"I'm sorry, you decided on your first guitar to leave out the UTBs because you didn't understand what it did and it was a bit ugly! Have you noticed that every guitar out there has them, steel strings, classicals. It is a major structural element of the guitar which helps stop the thing folding in half.
"
and time may well prove them right to have worried. However, I actually think my death-defying diamond design provides the “support such as flying buttress bracing” that the former advocates and, if I may be so bold, overdoes it. I think the rigidity built into the prototype almost stifles its ability to sing out so I am going to try to lighten it up a little this time. So here below are designs of the prototype bracing followed by the slightly changed bracing I’m planning for the two under construction:
The one on the right lightens some of the secondary bracing but I will also carve away a little more of the “diamond” to see how much I can get away with. The middle version resulted from a comment made by a violin-maker friend of mine who says “With violins, some people have tried making the strongest point of the bass bar [this is a brace] right under the bridge and this isn't helpful - you need the driving force away from the centre or strongest point, just like bowing a string in its middle has less effect than bowing nearer the bridge.” I wasn’t brave enough to shift the cross-over to the side and make the whole thing asymmetrical so I took an easier option and extended the diamond past the bridge area. Whether violins can teacher guitars anything is uncertain since the energy input is continuous when bowing a violin as opposed to a little pluck but it’s worth a try.
Hope you don’t find all this a bit excessive but I’ve got no one else to talk to about it!
Jo whoever he is.
