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Need help from fellow luthiers!
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=34263		 Page 1 of 1
Author:  utarazo [ Wed Nov 16, 2011 11:31 am ]
Post subject:  Need help from fellow luthiers!
I am in the process of building my first guitar, a Engelmann/Cocobolo/. I just ran into a bit of a problem. After i had finished my rosette i was sanding it down to get a proper thickness, problem is my being the first time builder, i was trying to sand it perfectly enough to get my rosette nice and crisp. Problem is i completely forgot about my overall thickness. The thickness of the engelmann is roughly between .080"-.090". It was a stiff top to begin with, and is still very stiff along the grain, but is somewhat flexible against it! Can i still use this top, or would it be better to just get a new one and start over?!.

Jonathan
Author:  Alain Moisan [ Wed Nov 16, 2011 11:51 am ]
Post subject:  Re: Need help from fellow luthiers!
What type of guitar are you making?
Author:  utarazo [ Wed Nov 16, 2011 11:58 am ]
Post subject:  Re: Need help from fellow luthiers!
OM size steel string acoustic!
Author:  Alain Moisan [ Wed Nov 16, 2011 12:21 pm ]
Post subject:  Re: Need help from fellow luthiers!
I think you are a little on the thin side. For a small body classical, you would have been fine, but for a steel string, even an OM, it might be stretching it a bit.

Given the fact that you are not that far in the building process, I'd start again and make sure you don't go under .100".

My 2 cents.
Author:  Dave Fifield [ Wed Nov 16, 2011 2:28 pm ]
Post subject:  Re: Need help from fellow luthiers!
+1 on Alain's comments.

If you want to, you COULD use that top to build a guitar by gluing a sheet of veneer to the back of it prior to gluing on the braces (best would be to glue the veneer on using a dish to shape it in a vacuum press). Most veneer in this part of the world is around 1/42" thick (0.024") so you'd end up at around 0.105" to 0.115" which would be fine. The sound of the guitar will suffer a bit, but that might not matter for a first/second build.

Cheers,
Dave F.
Author:  Corky Long [ Wed Nov 16, 2011 3:01 pm ]
Post subject:  Re: Need help from fellow luthiers!
Any chance you can measeure the density of the top? e.g. in grams per cubic inch? (yeah, I know... mixing apples and oranges).

If it's a particularly dense top, it might also be stiff enough at that thickness - yeah I agree. That's pretty thin, but you might get away with it if you don't thin it much more after it's put together..
Author:  Lars Stahl [ Wed Nov 16, 2011 3:09 pm ]
Post subject:  Re: Need help from fellow luthiers!
Or you could make a lattice bracing below the X and it might probably work great .. [:Y:] The first one is the one you should try it all on and learn from the mistakes on mistakes. Search the forum for lattice bracing. (double X below the main X)
My second was German spruce 0.87 thick, used lattice and it is one of my best sounding guitars too date. Once the braces are on sand them a little and flex, until you feel its right. nothing
can happen accept that the guitar becomes 2 guitars :D :D .. allthought... if your at 0.80 now and later need to fine sand it some more your on the 0.70 side and then your probably done for :?

Lars
Author:  Colin North [ Wed Nov 16, 2011 3:37 pm ]
Post subject:  Re: Need help from fellow luthiers!
Lars Stahl wrote:
Or you could make a lattice bracing below the X and it might probably work great .. [:Y:] The first one is the one you should try it all on and learn from the mistakes on mistakes. Search the forum for lattice bracing. (double X below the main X)
My second was German spruce 0.87 thick, used lattice and it is one of my best sounding guitars too date. Once the braces are on sand them a little and flex, until you feel its right. nothing
can happen accept that the guitar becomes 2 guitars :D :D .. allthought... if your at 0.80 now and later need to fine sand it some more your on the 0.70 side and then your probably done for :?

Lars

0.87 thick - if I don't pick you up on the decimal point someone else will.
I'm know you meant 0.087, just a slip of the finger.
Author:  utarazo [ Wed Nov 16, 2011 5:19 pm ]
Post subject:  Re: Need help from fellow luthiers!
thanks everyone, i think im going to take this as a learning opportunity and experiment with a bit stiffer bracing pattern or even try the suggested veneer idea. Being im a beginner i will have to figure out how it sounds afterwards, what kind of sound should i look for when taping it after bracing?!..a more sustained ping?!..any help would be greatly appreciated! I also attached a pic of the guitar so far let me know what you'll think. I will be doing back bracing tonight!

Jonathan

Image

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Author:  Ken Franklin [ Wed Nov 16, 2011 6:04 pm ]
Post subject:  Re: Need help from fellow luthiers!
You could turn it into a double top with a nomex core. Or I think Peter M makes double tops without nomex. Maybe he'll chime in.
Author:  truckjohn [ Wed Nov 16, 2011 6:54 pm ]
Post subject:  Re: Need help from fellow luthiers!
Or you could just use it anyway.... In all likelihood - it will be OK....

If you do decide to use it... make sure your X-brace completely overlaps the bridge feet - not just the tips of the bridge wings... Also make sure that your tone bars, bridge plate, and finger braces tightly butt into or are inletted into your X-brace.... It would also be a good idea to incorporate an A-brace between the X and the head block....

Thanks
Author:  alan stassforth [ Thu Nov 17, 2011 11:10 pm ]
Post subject:  Re: Need help from fellow luthiers!
Since it's your first,
you might consider putting it in storage for a while,
until you figure out what to do with it, later on,
after you have more experience.
Go with whatever the plan you are using at this point says the thickness should be,
get another top.
You will put many hours into this guitar,
and it would be a shame,
if it imploded when puttin' da strings on.
"Might make you give up on luthing.
Start heavy,
thin down later, when you know what yer doing".
Sounds like a song!
Author:  nickton [ Fri Nov 18, 2011 1:28 am ]
Post subject:  Re: Need help from fellow luthiers!
If you only thinned it too much around the rosette I would just do a circular sound hole re enforcement like one sees on many classical guitars, using a left over scrap of top wood under the sound hole area. this would not even be considered incorrect I think.
Author:  Corky Long [ Tue Nov 29, 2011 2:08 pm ]
Post subject:  Re: Need help from fellow luthiers!
It hasn't been said yet, but you should probably use light strings on that guitar.... Even mediums might be too much for it if you build with that top. But again, my vote is that you soldier on. If I'd done a "redo" every time I screwed something up on my first guitar, I would never have gotten it done. It's tricky deciding which errors are really important to totally correct, and which you can work around. (and there's probably as many answers are as there are people reading this post.... :lol: )
Author:  theguitarwhisperer [ Tue Nov 29, 2011 4:05 pm ]
Post subject:  Re: Need help from fellow luthiers!
In all likelyhood the braces will telegraph through the top, and it may belly a little sooner, but it will work fine. Doesn't look like you are making a huge body.
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