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Opinions on bracing for my Petite Jumbo http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=13833 |
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Author: | Allen McFarlen [ Sat Sep 29, 2007 8:34 pm ] |
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I've been building from Scott Antes plans for my first 4 guitars, and wanted to venture out with a body shape of my own. I really like the smaller body guitars, but love the look of Jumbo's. I've built the mold this weekend and now waiting for wood orders to arrive in the mail. I call this one a "Petite Jumbo" (yes, I'm aware of the oxymoron). It's 15 1/8" across the lower bout, 10 1/4" across the upper bout, and 19 1/4" body length. I also think that it would be easy enough to add a spacer between the 2 halves of the mold to increase the width for something a little different. I used a pretty standard bracing pattern but liked the idea of the sound hole braces extending through the upper transverse brace and into the fingerboard extension support. I've been reading recent threads about the sizes of the X-braces, tone bars and finger braces. Most notably some posts saying that they had downsized the X-braces on 000 to 7mm wide from Antes plans that stipulate 9.5mm. As this is the same size as a 000 but just a different shape, any opinions on what I have drawn up here so far? I use parabolic bracing and solid linings. All opinions gratefully accepted. |
Author: | bob_connor [ Sun Sep 30, 2007 12:28 am ] |
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Hi Allen We're doing one with almost identical dimensions to yours but the upper bout shape is a little different. The braces in the one below are at 8mm. It is for a 12 string and yes it is a left hander. I'm also doing another one of these and I'm going to put 6mm braces on that one (it has a much stiffer soundboard) Your bracing looks fairly similar. The first one should be completed in about 3 weeks so I'll let you know what it sounds like then Here's what the shape looks like in comparison to an OM Cheers Bob |
Author: | Lillian F-W [ Sun Sep 30, 2007 1:47 am ] |
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Bob, the more I look at your big bottomed girl, the more I like it. I have to wonder if moving the waist up is going to make a difference while playing seated. If it does I'm sure it will be an easy adjustment. I might have to see if I can talk you into a tracing of the body. |
Author: | TonyKarol [ Sun Sep 30, 2007 2:35 am ] |
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I would make the X no more than 7mm x 15mm, possible 6 in width depending how thin/felxiable you make the top itself. I would also highly recommend opening up the X, and pulling it forward a couple hairs, I feel you have too much bridge to X brace overlap. I like the X to come out the end of the wings of the bridge, definitely not the back. However all the above depends on how you shape the braces - I dont scallop at all, only taper from the X joint to the edges - sometimes a slight valley, but only if the guitar will never see med gauge strings. |
Author: | Allen McFarlen [ Sun Sep 30, 2007 7:15 am ] |
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I've looked at the x-brace a lot and thought it might be just a bit too far back. That's an easy adjustment to make. I'll wait for some more feedback and then redraw and post an updated plan. The first one is going to be California Red Wood/Mahogany. I'm going to join the top plates in the next day or so and will get an idea of the stiffness. I have some really nice Western Red Cedar that I was considering for brace wood. Anyone use it for braces? |
Author: | Allen McFarlen [ Sun Sep 30, 2007 7:16 pm ] |
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Here's an updated plan. The top is 2.8 mm thick and I would say its moderately stiff across the grain. I managed to get is joined up after work today. I just laid out my fret scale rule on the original plan, (Martin long scale) and the bridge is in the right spot. Opinions on moving the bridge plate back a bit, or size it to be just a tad larger than the bridge, say 5mm front and back? |
Author: | Bruce Dickey [ Mon Oct 01, 2007 3:24 am ] |
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Looks Great. Time to glue, carve, and sand.... |
Author: | Allen McFarlen [ Mon Oct 01, 2007 7:05 am ] |
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Thanks for the feed back. I'm going to start on the rosette tonight. I'm going to use 7mm X 15mm for the X-Braces as suggested. 6mm for the tone bars and the finger braces. |
Author: | Allen McFarlen [ Sat Oct 06, 2007 4:42 pm ] |
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Got the rosette done and have the x-brace glued onto the sound board. The x-braces and upper transverse brace have been notched for the 6x6 mm upper sound hole braces. I don't radius the upper transverse brace, just glue it in flat. I had planned on slipping the upper sound hole braces into the notches cut in the x-braces, then laying the upper transverse brace over top and gluing them in as a unit. All of this was fiddly but not all that difficult. Now comes the part that has me a bit stumped. How should I build the heel block with fingerboard extension? If it didn't require the sound hole braces inlet into it precisely then it would be easy, but I'm having a hard time visualizing how to accomplish this. |
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