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Steel string double top - and hello
http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=2117		 Page 1 of 1
Author:  Jim Watts [ Tue Jun 07, 2005 4:57 pm ]
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Hello all,
I new here (lurked a while ) but thought I'd I introduce myself with a double top guitar I recently finished, it was an experimental guitar for me. I spent a large portion of my career as a composites engineer so I have been draw this idea for a long time.
This is my first post here so I'm learning how the forum software works posting pictures and all. Any way here we go.

The guitar sounds great, its been strung up now for about 12 days or so and the sound is still developing. It has a really strong bass yet the trebles are all there too, nice and clear. Many people have heard it and I always ask them to try to describe it and the adjectives that are on almost everyones list include: resonant, well ballanced, vibrant, and alive. It's pretty loud, just a little louder than most guitars but i expected it to be louder for some reason.

Happy to answer any question people may ahve about the double, but just to warn you I,m not the fastest or most ferquent poster, but I'll try.






Brock Poling38511.3508217593
Author:  Jim Watts [ Tue Jun 07, 2005 5:01 pm ]
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Looks like I don't quite have the posting thing down yet.
Author:  John B [ Tue Jun 07, 2005 5:22 pm ]
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You just need to put some carriage returns between your pictures (or hit the enter key, depending on when you learned to type).
Author:  Josh H [ Tue Jun 07, 2005 10:27 pm ]
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Jim

Welcome to the forum. Great looking guitar. Thata double top idea looks really interesting.

Where did you learn to build? And what kind of finish are you using?

Josh
Author:  Don Williams [ Tue Jun 07, 2005 10:32 pm ]
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Cool looking work!

Like John said, just go back and edit your post and put hard returns in between your pictures, and set them to left justification. Easy
Author:  Brock Poling [ Tue Jun 07, 2005 11:24 pm ]
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fixed
Author:  Jeff Doty [ Wed Jun 08, 2005 12:04 am ]
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Jim,

Welcome to the forum. Please tell us more about the guitar, and your building experience. I would love to see more pictures too, that looks like a really nice guitar!

Jeff
Author:  Robbie O'Brien [ Wed Jun 08, 2005 12:27 am ]
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Beautiful work! The double top is very interesting, thanks for the pictures!
Author:  Wade Sylvester [ Wed Jun 08, 2005 3:52 am ]
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Jim,
This looks real interesting.
How is it assembled?
Thanks for sharing.
Author:  Jim Watts [ Wed Jun 08, 2005 5:43 am ]
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Thanks for the welcome. I just read my post from last night and realize it's almost illegible with spelling and grammer mistakes. Wow, well that's what happens when you post at midnight I suppose after a long night in the shop.
Brock - Thanks for fixing the pictures in my post.
To answer a few of the questions, I've been building 10 years and had the good fortune of learning from Tom Ribbecke, great teacher.
The finish is Nitro.
Back and sides are EIR with an X brace pattern on the lower bout.
Neck is mahogany with carbon fiber reinforcements.
I'm not sure I understand the question about assembly, but if you could elaborate I would be happy to try and answer.
Author:  John How [ Wed Jun 08, 2005 5:55 am ]
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I think Wade is talking about the top construction. There is going to be a lecture at Healdsburg this year about double tops. I'm looking forward to hearing the story.
Author:  crazymanmichael [ Wed Jun 08, 2005 2:27 pm ]
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good to see you here jim.

i too would like to learn and see more about the top making procedure, and unfortunately i won't be going to healdsburg.
Author:  Jim Watts [ Thu Jun 09, 2005 5:11 am ]
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Here’s the run down on the top construction in general terms, and I’d be happy to answer in more detail if questions arise.
My tops or skins as I like to refer to them are Sitka.
The honeycomb is 1/8 cell size Nomex with a density of 3lbs/cu ft.
The overall thickness of my top is about 15% thicker than my normal tops.
I start by joining a top and thicknessing it to about .13 or so.
I then vacuum it to a flat plate and route the pockets for the honeycomb.
I bond the honeycomb into the pockets as show in one of the pictures above with epoxy (not too much, just the right amount) in a vacuum press.
Sand the whole thing to what you want the finished top thickness to be, minus the thickness of the second skin. My finished top is about .130 maybe a touch more under the bridge area and tapers out a little towards the perimeter.
Join up a second top and thickness sand this to you desired thickness, .038 in my case.
Bond this skin to the first skin with the core in it, using epoxy, again not too much just the right amount.
Now you can cut your sound hole and inlay your rosette as you normally would.
The key here is accurately laying out you finished top prior to doing any of this. I used locating pins to accurately align my template for cutting the pockets for the honeycomb.
Another thing to keep in mind is that you don’t have much material in the skins to tap tune as many normally would. You can really only tap tune by shaping the braces not changing the top thickness. I’m not sure tap tuning the unbraced top would work any way as it will sound way different than what you use to.
Any way hope this answers some questions.
Author:  Wade Sylvester [ Thu Jun 09, 2005 6:01 am ]
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Thanks Jim,
It's a little clearer now.
I was not familiar with this technique of double tops.
I’d be interested in finding out more.
   John, take notes if you would.
Author:  crazymanmichael [ Thu Jun 09, 2005 6:56 am ]
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whilst i knew they existed i also was totally ignorant of the technology/technique of the world of double topping.

now could you explain a bit of the why of it? also why you choose to do some with doubled tops and some without? what factors are involved in your decision?
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