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Ken_N

Inside First

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Well the mold worked, but if I were to make another model guitar, it would have on outside mold.  It is far simpler.

The sides will need some coaxing to get where they're supposed to be.  This photo shows the high arch on the back. 

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I don't know if it is normal, but the cutaway made a crease in the arching that adds a lot of stiffness.

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It is 350 grams now.  I started doing the recurve at 500 grams.  The tap tone did not drop, it only became more flexible, and there are more tones all over.  It is at 370.  It seems really high doesn't it?  Maybe that's not M5.  Whatever; it's been there the whole time.

I made a little plane to smooth out the groove for the truss rod.  I wasn't going to use one, but "everyone" insisted.  I drilled 3/16 holes along the length first.  It worked great.  Now I'm fitting the joint for the head.  The birdseye for the neck wasn't long enough to cut out the head with the neck, so since it is supposed to be a late 18th century guitar from Guadagnini, I used the typical v joint.  It isn't too hard, but far more trouble than a scarf joint!

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19 hours ago, Ken_N said:

20190507_135124.thumb.jpeg.680a2eb1f407dd893b72c6ff82d7887f.jpeg

It is 350 grams now.  I started doing the recurve at 500 grams.  The tap tone did not drop, it only became more flexible, and there are more tones all over.  It is at 370.  It seems really high doesn't it?  Maybe that's not M5.  Whatever; it's been there the whole time.

Your total side depth/height should be around 3" total.  Total means the outer thickness of your plate edges and rib heights combined.  So if 76mm is the total height suggested by me and you have two plates with 4.8mm edge heights each that should equate to let's see............ 66mm or so ribs heights needed only - don't go much higher.

As for m5 tap tone and hz.  These plates very well may be hovering around the 95 hz to 150 hz area when graduated correctly - I'm not really sure.  I'm just trying to compare a smaller plate of a violin to a 4/4 violin plate hz wise.  The smaller plate rings higher tone than a 4/4 plate hence my speculation of a bigger archtop plate ringing lower than a 4/4 violin plate.  I'm not really sure but my point is I'd like to see you get this all right the first time around tonewise and playability.

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The numbers were when I started.  Now it is 4 around the edge.  3-3.5 in the recurve and across the bouts.  The center is from 4-6 mm.   The thickness flow gradually downwards from the middle.  They don't rise at all until maybe 20 mm in.  I want a 10 mm fancy edge, like would normally go around a sound hole.  I'll finish tuning it when it is glued on the sides, and the edgework is in. 

I tapped it just now listening to an online tone generator.  The lower three are balancing on the center, and tapping the edge.  The other five are holding around the edge, and tapping around the plate.  There are notes all over the place.

65 C2

82 E2

109 A2

165 E3

235 Bb3

330 E4

350 F4

370 F#4

Maybe you could just call it E.  

It's no where near flimsy.

The belly is still thick, I want to put the f holes in before I thin it.  It is 350 grams too, and is basically 6-7mm thick, and 5 around the edges.  It is very resonant.  It will end up lower than the back.  It sounds way higher, but it is just so lively.  A quick check gave:

82 E2

165 E3

195 G3

388 G4

It has some flex already.  Not quite as much as the back, but more than the back had when it was 30% heavier.  

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I've done some things on the guitar.  The neck and back are glued on.  The belly is down to 248 grams, and is about ready for the diagonal braces.  I won't make them as tall and wide as suggested in the book.  I want to use nylon strings, and will have a lot less pressure on the belly.  Nylons go from 90 - 110 pounds, while steel has a much larger range: lights at 135 or so, and heavy gauge at maybe 180.    

I figure it at two thirds.  

Once I get the belly glued on, I can cut the edges down, and tune it.  Fingerboard extension, fingerboard, frets, and all the setup and finish stuff.

 

 

 

 

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