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Andyjr1515 last won the day on July 13 2019

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  1. No - it's a 600mm wide slice off a 25 foot 50 foot sphere and so is a couple of mm deep
  2. And here we are with the braces as fettled as I dare. Certainly there is a pleasing variety of tones across the various points and so I think this is the point to stop: Note that the main cross braces and the horizontal one next to the heel block all will lock into notches that will be cut in the lining but that the ends of the slimmer 'tone bars' fizzle out into nothingness at various places. There will be some thin reinforcement strips around the back of the soundhole but my attention will now be turning to the much more straightforward braces to go on the back. And for that, out comes the 15 foot radius dish. Yes - another radius dish! There are some scary bits with acoustics (and most of them are still to come!) - but there is something deeply satisfying about the above
  3. And the braces are on ready for fine tuning I've roughly profiled the cross sections to a more triangular/parabola shape. Next steps will be to add the maple bridge plate and there is a small strengthener that goes across the X brace centre joint. Both of these make a difference to the flex of the top and so need to be in place before I do the final tap-tuning. Having said that, it already is returning a wide variety of notes and harmonics, which bodes well
  4. Hi Richard Not too difficult. Just some mathematics to work out the depths at a series of radii, a router on a radius bar to rout the contour depths and then a curved cabinet scraper to join up the contour lines. The challenge was the dust. I could not believe how much dust was created - and mdf dust is pretty dangerous stuff...
  5. I'm really not at all sure. The engineer in me says that it creates a tension in the top woods and that increases the harmonic potential (it is the harmonics from the top rather than the basic 'drum' pitch that seems to sort the men from the boys in terms of acoustic guitar quality). But the pragmatist in me says that I'm just going to follow what the majority of the best builders do
  6. And while the bracing is drying, there is time to start putting the linings around the edges of the body sides. These held strengthen and stiffen the body but their main function is that the top and back will be glued onto these. While the edges are also glued, those joints will actually be routed away to fit the binding on the external edges. The kerfing (the saw cuts) allow the linings to bend round the fairly tight bends of the sides. The clothes pegs with stiff rubber bands wrapped round provide more than adequate clamping all the way round while the glue dries. At this stage, the linings are set a mm or so proud of the sides because - on account of the top and back being spheroidal - they will be planed at an angle and sanded in the radius dishes to produce a good fit all the way round prior to gluing.
  7. I don't know why it's called a Go Bar Deck...but it is. Basically, two pieces of chipboard held apart by some sturdy bolted treaded rods; the radius dish placed on the bottom; flexible rods (the Go Bars) pressing down the curve-bottomed braces into the radius dish while the glue dries: And here are all but the last four small braces. This will be left overnight for the glue to fully cure and dry and then I'll add the last four braces. And then we will have a subtly spheroidal top ready for the braces to be slimmed in cross section - and then the tap tuning can commence
  8. Actually, that is the next but one step after this - the dark art of tap-tuning...
  9. And so to the top bracing. The Bouzouki is based on an OM acoustic guitar and the bracing pattern will be identical. And it's all a bit precise. Legend has it that Martin in the thirties (?) did a bracing pattern that just, well, worked. And from that point 90 odd percent of acoustic guitars have been, and still are, made with the exact same bracing pattern. I may well have my facts wrong but my philosophy is that - like banging dustbin lids to keep the elephants away - it works so that's what I'm going to continue to do! So, for those who haven't seen an acoustic build before - a flat-topped acoustic generally isn't flat. Most have a spheroidal shape of around 25 feet radius for the top and 15 feet radius for the back. So you have to make (or buy) a 25' and 15' radius dish, you have to curve the bottoms of the braces and then you have to press the braces into the dish to force the flat top into the final spheroidal shape. The process will become clear soon (probably tomorrow), but today I was cutting the braces blanks for the top. This is a straight piece of spruce sitting across the 25' radius dish: It's subtle. But the bottoms of the braces have to be planed and sanded into a curve - and because it's a sphere, the actual curve needed is different depending where each brace is going to fit. First is the well known 'X' brace which is two pieces curved underneath and locked together: And here it is in position on my home-made MDF 25' radius dish. Difficult to see, but both lengths are now completely gap free on the dish: The braces will have a LOT of work done on them, but it makes it a lot easier to remove some of the bulk by starting to cut them to side profile, especially in terms of the positions (again, very precise) of the peaks you can see below - the 'nodes'. Here we now have all of the braces for the top, rough-profiled but finish-fitted on their under-sides to suit the radius dish at each of their respective positions: And tomorrow, these will be glued and pressed into the radius dish to form the basic top shape. I might do some work on the cross-sectional profile of some the braces before they are glued in...I'll have a think about the best way round to make the access for the final shaping of the braces as easy as possible.
  10. And we're back! The rest of the wood has arrived And based on the size of the bill...and our last Sainsbury's one too...I think that the Bank of England might be right about the economy heading towards a 'V' bounce back in a number of business sectors!!!
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