The next one

Dave!  You really must take more care over reading my posts.  Ponder every word and click every link...

...till I wake up where the clouds are far behind me, where trouble melts like lemon drops, high above the chimney tops that's where you'll find me...

Sorry davewhite - the image of your prancing across an open field in leather shorts is not good at this time in the morning....

You're a cruel and heartless man, Kym, smashing my fantasies to pieces around my feet and crunching the bits under your heels.  You must pop round some time;  I have to almost beg people for criticism but yours is straightforward and very useful.  But I think you're a bit far away for a cup of coffee later this morning, aren't you?

On the other hand....  you are sailing quite close to the why-the-hell-don't-you-just-make-a-proper-normal-guitar-that-someone-might-even-want-to-buy way of looking at things and I have some sympathy with that (as does my wife) but no one would want to read about my next build and I'd be all alone in a workshop listening to Radio 4 without a friend in the world - even if I had sold a guitar.  Tugged the heartstrings?  I can only quote Leonhard Augenstein (interviewed by nkforster on his Luthier Blog) who put it like this:  "I do not see any sense for myself to repeat and copy what thousands of other guitar makers and guitar factories are doing.  A guitar is something beautiful and people that are playing and buying guitars should have unique instruments that are inspiring them for their own playing."  My English is more correct than his but less poetic and our sentiments match exactly except that I would add "much better than I ever could" at the end of the first sentence.

I don't actually have a bridge-plate because there's too much bracing directly beneath the bridge to make it a practical option.  This is clearly a big part of my problem and is why I am looking at ways of spreading the load behind the bridge, though you're probably right that I should also be keeping my eye one what's happening between the bridge and the soundhole.  The lack of a bridge-plate means I can't use conventional pins (and, besides, have you seen the price of a reamer?!), which is my excuse for having such an odd (and delightful) bridge, which (incidentally) makes changing strings incredibly easy and is one of my few successes in guitar-building life.

The Larson brothers' metal rods I understand completely, having used virtually the same thing in my carved archtops, but I think I see more logic in davewhite 's carbon-fibre flying buttresses with a flat-top because the bit that needs supporting is between the bridge and the heel rather than between the tail and the heel.  

The idea of the bridge as a brace always strikes me as one of these things that everyone believes because they've read it somewhere and that was just someone repeating what they'd read somewhere...  If you look at it structurally, it seems to make more sense to have a bridge with a longer north-south dimension and with the grain running north-south because the torque of the strings is trying to rotate it down at the front (and up at the back).  (Leonhard Augenstein also seems to be doing this on some of his guitars along with others perhaps - Nigel Forster?).  That's one of the reasons for putting a bloody great "bridge-plate" underneath;  but it's not a very elegant solution when everything on the surface is made to look so refined and delicate.

So where does all this get me?  Well, I've more or less abandoned (for the time being!) the idea of anchoring the strings down by the tail because it opens upon a Pandora's worm-tin.  And the so-called Larson brothers inspired bracing pattern is clearly overdoing it somewhat.  But I might move towards something with a similar layout and a lot of light bracing (always avoiding the 12mm mdf look) which still retains the bridge as an integral means of locking together a basically radial pattern - see motorbike-engine analogy in Beefy Bryn.  I'm also going to consciously leave quite a lot of meat on the central spine of the soundboard to help with its fundamental integrity.

Does that make sense?  Thanks to you, Kym and the others (richm , davewhite , francis ) for your humour, help and horror;  I've never instigated such a flurry of activity over anything before!

Now he tells me!  

So-called Beefy Bryn will, I think, deliver a better sound and be more responsive than I have previously managed but I've only had one visiting player so far and he doesn't know me well enough yet to say what he really thinks;  he thought all my guitars were utterly unbelievably fantastic, by the way.  To my limited old ears it sounds great.  I've left it in its buzzing and bulging state so far because I want it playable if anyone else responds to my plea for players.  There are two "problems" with it:  the neck angle (causing buzzing) and consequent high saddle;  the bulge, which may not be terminal and may be helped by lowering the near end of the fretboard and thus the saddle - if you follow.  Therefore my path and end goal with the next one is to hold on to my successes but to take more care with neck-angle and with bridge support.  

Can I say that I introduced my Wallace and Grommit design with these words:  "Does anyone know who has done something like this in the past?"  I was merely wondering if anyone on the forum knew of such a guitar and what it might sound like because it's an entirely different beast;  it's much more like a carved archtop in terms of tensions and response, I would imagine - as are the instruments you have built with end-to-end bracing where the strings run end to end.  You don't use end-to-end bracing on guitasr which have strings attached half way along the soundboard, do you?

Thanks for helping me to clarify my thoughts, Dave.  I'm going for a run now (and may be some time) so god knows what I might have come up with by lunchtime!

Rob,

Just a comment with regard to the flying buttress braces (fbbs). The rim (sides and end blocks) forms an incredibly stiff and rigid structure especially when the top and back go on and close the box. Having the fbbs attach just behind the waist and into the head block intuitively to me takes maximum strength advantage of integrating with the rim structure - in effect they follow the rim from just below the waist around the lower bout. Where your first diagram shows them joining the sides is a much weaker arrangement to my mind. I'm sure the engineers can provide the maths to prove which of the two connection points provides most resistance to the string tensions rotational torque on a pinned bridge.

R the F I'll let davewhite discuss the merits of the carbon rods. My concern is how you've shown the ends of the extended bridge plate. Having in effect a 'pocket' joint with the bridge sitting in it, the squared ends are weak points front and back. It would be better if you taper the front and back edges from full depth under the bridge to nothing where the ends emerge from the soundboard - probably either side too.

Still struggling with the rational on this one....