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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on May 15, 2015 6:41:16 GMT
Sorry to keep you on tenterhooks but I'm a furniture restorer and I've spent most of the last few days making a dining table 285mm narrower. It's an exciting life! I'll try to get the bridge on this afternoon, though, and then see where we get to over the weekend.
Thanks for your concern, Rob
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on May 14, 2015 7:23:12 GMT
Spot on again. I started out trying to "do a Sobell" since I do like the look of his guitars and the arching made sense to me - note my neck joint and purfling, too...
I only worry that the combination of that arching and all the north-south bracing might entirely prevent the soundboard from vibrating at all! I just fall back on the idea that tiny vibrations may still be compatible with a structure which, as a whole, is rigid (as far as catastrophic failure is concerned) - if you follow. We'll see.
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on May 13, 2015 21:46:30 GMT
Here's the view from the end:
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on May 13, 2015 19:59:43 GMT
Well spotted, sir. The front is about 6 foot radius (1775mm) and the back even tighter at 4 foot (1182mm) - but only side to side. It didn't make sense to me to bend it lengthways because that's where you want to stop it bending.
Thanks for your interest, Rob
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on May 13, 2015 8:56:42 GMT
Yesterday I finished making the bridge and took some photos so that’s where I’ll start this account.
It’s made of laburnum stained black with iron acetate (nails in vinegar) with the grain filled with shellac and then waxed very lightly. It’s very nice to handle and looks like something out of Star Wars but that doesn’t mean it will hang on to the strings when it’s attached to a guitar!
It weighs 25gms and covers, I suppose, about 80% of the area of a more typical design at 4260mm² so shouldn’t give the glue any problems if I make a good job of preparing the surfaces. In fact, those seven little holes you can see should make it absolutely sure that it doesn’t do a Star Wars and set off across the galaxy; they are for ?” dowels which will fix it securely to the braces beneath the soundboard.
That explains the 6 bed-pan-shaped holes as well. Since there are braces under the bridge area, there’s really nowhere inside the guitar that ball-ends can happily settle if the strings are fixed with a more traditional peg system. I cast around a little to solve this problem and then discovered that there are one or two steel-string guitar makers who attach the strings to the bridge itself (not to mention classical makers) so that is what I have done. The holes are slightly angled so that the ball-ends can’t get off the surface of the soundboard when they are under tension. I have also orientated the grain north-south to help deal with the stress that the bridge will need to deal with.
I’ve had to make a special caul to put pressure on from underneath when gluing the bridge in place. It is curved and shaped to avoid the braces and only touches the soundboard itself. Here’s a picture of it.
My explanation for having a Spaghetti Junction of braces directly under the bridge is twofold:
First I was trying to design a bracing system which, on paper at least, seemed to me to more directly confront the problem of the guitar trying to fold itself in half under string tension. I’m not quite sure how the conventional layout deals with 80 kilos of pull (though it clearly does so) so I set about reconfiguring things so that they made intuitive sense to me. Obviously my intuition may be way off the mark but that’s part of the excitement. I just don't like blindly following something that I can't explain to myself let alone anyone else. What I came up with is an attempt to transfer the stress directly from the end of the neck as it enters the box to the sides of the guitar at their tightest curve (strongest point) and then directly down to the bridge area where the the other end of the strings are attached. Now, unfortunately, a guitar should be rather more than an attractive arrangement of heads and necks and boxes that can put up with a great deal of tension; it is also supposed to sound good when played. I haven’t really catered for this aspect of things here so…
...secondly, it seemed to me that, since the idea is to make the whole braced soundboard sing, then – again intuitively and with no evidence or experience whatsoever to back it up – it makes good sense to me to put the bridge right at the point where the braces can take the vibrations and radiate them out across the soundboard. So, rather than put the bridge on a blank patch of soundboard hemmed in by braces, I am going to put it right at the hub of the spokes.
Here is the design that resulted:
And here is a picture of things as they stand today:
This is the first flat-top guitar I have made and I will no doubt look back in embarrassment at my foolish attempt to reinvent the wheel without knowing the first thing about circles but… what the hell (as someone said). Over the next few days I hope to be attaching the bridge to the body and then the strings…
Will it implode?
Will it sound like a drawer full of socks?
Watch this space and find out!
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on May 11, 2015 19:02:26 GMT
You make it all look so straightforward. It's not. Loverly job.
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Apr 12, 2015 21:37:20 GMT
Interesting stuff – and part of a pattern, I reckon. It fits in with things I’ve previously read/seen about experts blind-tasting wines, hi-fi experts blind-listening to different set-ups , even average folk trying to discriminate between bottled and tap-water or between white and red wine. They all swear blind (excuse me) that they can tell the difference and they always end up with a result that shows that they can’t if you test under strict conditions. I don’t think that necessarily invalidates “expertise” but it does show that it’s the whole package (i.e. we like the look, packaging, history, folklore etc. etc. which goes with whatever it is) and shouldn’t kid ourselves that we are as subtle and objective as we like to think. But some people, of course, make a living out of this so we have to tread carefully!
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Apr 11, 2015 9:39:41 GMT
Sorry to be a bore, chaps, but this UTB thing is bothering me and I won’t take “envelopes” for an answer!
To be serious, then. I know that it is said to be there to stop both ends of the guitar sliding together into a black hole under string tension – but surely the string tension will tend to fold the guitar if it finds a big solid bar preventing a slide; like standing against someone’s feet before you try to pull them up off the floor.
I have also noticed that 99% of guitars have them; but that doesn’t explain anything. We all have an appendix (to start with) but that doesn’t mean it’s any use to us. What I am looking for is an engineering explanation (I suppose) as to how this works as a “major structural element of the guitar which helps stop the thing folding in half”.
I’m certainly not suggesting I know any better than thousands of makers before me but it seems to me that contemporary luthiers are generally a reliable and sharing bunch who will take a hard fresh look and apply proper logic to what they are doing. Somewhere someone must have explained how the UTB does what it’s supposed to do; or does everyone assume that someone else must know?
I might also ask why the wood-grain on a bridge isn’t orientated along the length of the guitar – but that’s a question for another day.
Thanks for your patience.
Rob
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Apr 11, 2015 8:27:38 GMT
I decided UTB must mean "Ugly Thick Bit" when I was trying to understand how bracing worked. So, perhaps foolishly, I decided to miss it out and see what happened on my first build! I've nearly finished the guitar now and I still can't quite see what it does so... can someone (point me at something that will) explain. It is big and it is a bit ugly so I'm sure it does something or other but it just seems to be doing it in the wrong direction. No doubt I'll come to understand why it's there when I put strings on the thing... 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. I realise that's the conventional view but I just don't see how it was arrived at. I mean, if I didn't want the postman to fold something lengthways, I wouldn't put something stiff across the package, I'd put it lengthways. You might as well put a dotted line on the Ugly Thick Bit and write "please fold here"! Thanks for trying to unmisguide me anyway.
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Apr 11, 2015 8:08:34 GMT
I decided UTB must mean "Ugly Thick Bit" when I was trying to understand how bracing worked. So, perhaps foolishly, I decided to miss it out and see what happened on my first build! I've nearly finished the guitar now and I still can't quite see what it does so... can someone (point me at something that will) explain. It is big and it is a bit ugly so I'm sure it does something or other but it just seems to be doing it in the wrong direction. No doubt I'll come to understand why it's there when I put strings on the thing... 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. Off to fire arrows. Colin Sounds as if you might as well use my box for target practice! Good shooting!
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Apr 10, 2015 22:34:08 GMT
I decided UTB must mean "Ugly Thick Bit" when I was trying to understand how bracing worked. So, perhaps foolishly, I decided to miss it out and see what happened on my first build! I've nearly finished the guitar now and I still can't quite see what it does so... can someone (point me at something that will) explain. It is big and it is a bit ugly so I'm sure it does something or other but it just seems to be doing it in the wrong direction. No doubt I'll come to understand why it's there when I put strings on the thing...
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Mar 30, 2015 18:05:14 GMT
Thanks for the prompt response. Yes. I was adding the same (3mm) "margin" all the way along the fretboard. I see the point now of swelling it towards the half-way point - and, yes, I already know I'm in serious danger of disappearing up my own bottom on these matters; I have swathes of full-size drawings of what I'm making - printouts from the cadcam program I use in fact - but I still missed the point! There's nothing to beat a quiet word from someone who's done it all before.
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Mar 30, 2015 11:42:30 GMT
I come a little late to your build but it's been of enormous help to me over the last couple of months as an aspiring builder of guitars; enormous gratitude for the trouble you have taken over it. I've even transformed it into a "to do next" list. However, I'm just sorting out a fretboard and I've been stumped to understand this: Is there a typo here? Should "larger" read "narrower"? If so, I can stop tearing my hair out! By my calculations, a 46mm nut gives a 40mm string spacing at the nut (allowing 3mm margin either side), which gives you a 54.5mm board width at the 12th fret (assuming a 63mm notional board width at the saddle i.e. 57+3+3).
Thanks again for the thread and sorry to be a bore.
Rob
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Mar 28, 2015 19:32:11 GMT
I give up, then.
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