Official Luthiers Forum!
http://www-.luthiersforum.com/forum/

top braced Australian blackwood?
http://www-.luthiersforum.com/forum/viewtopic.php?f=10101&t=47693		 Page 1 of 1
Author:  dertien616 [ Wed Apr 27, 2016 8:34 pm ]
Post subject:  top braced Australian blackwood?
I am working on my second guitar and im using Australian black wood for the top sides and back. I dont really know what to listen for yet when im voicing. It sounds ok but i feel like it should be ringing out longer. hopefully the pictures help. here are some measurements i took. i feel like it might be over braced but really have no idea..

tone bars- 4mm at the x brace then goes up to 8mm back down to 4mm then up to 6mm 3 inches from the edge and scallops down to nothing

X brace- goes from 12mm at center to 3mm on the upper bout x braces and lower bout the braces go from 12mm at center down to 7mm then back up to 9mm 3 inches in from the edge and then scallop down to 3mm around the edges.

bridge patch - 3mm

finger braces- 7mm and scallop to nothing
Author:  Tom West [ Thu Apr 28, 2016 7:43 am ]
Post subject:  Re: top braced Australian blackwood?
And the top is how thick.............? Most of the weight for a top SYSTEM is in the top plate. Not sure of the weight of Blackwood but no doubt the weight to stiffness is not as good as a spruce or cedar. You may not be over braced but rather over topped.
Tom
Author:  dertien616 [ Thu Apr 28, 2016 7:47 am ]
Post subject:  Re: top braced Australian blackwood?
My top thickness is between .90 and .95
Author:  dertien616 [ Thu Apr 28, 2016 8:02 am ]
Post subject:  Re: top braced Australian blackwood?
I typed that wrong. It's between .090 and .095
Author:  Tom West [ Thu Apr 28, 2016 8:11 am ]
Post subject:  Re: top braced Australian blackwood?
Your top is certainly on the thin side. Do you do any deflection testing ? I have never worked a top made from any wood other then spruce and cedar, so not really sure what to tell you. Does not look over braced if they were on spruce but at that thickness and the heavier weight of blackwood compared to spruce maybe your plate is quite loose. Hard to tell without have top in hand. Not much more I can add.

Tom
Just one thing for next time, the width of your braces, less width and higher. IE A lot of X braces are 5/16" by 5/8" I tend to use 1/4" by 11/16". This help to drop weight and leave you with the same approximate stiffness. Only so much power in the strings ........less weight equals more responsiveness. Take care.
Author:  Tom West [ Thu Apr 28, 2016 8:13 am ]
Post subject:  Re: top braced Australian blackwood?
dertien616 wrote:
I typed that wrong. It's between .090 and .095


Yeah.........had it figured out...!!
Tom
Author:  dertien616 [ Thu Apr 28, 2016 10:54 am ]
Post subject:  Re: top braced Australian blackwood?
All the braces are 1/4" wide. I did deflection test the top an with a 5lb weight and 18" spread it dropped 1/4". I thought the top sounded really good and then I put the bridge plate on and it really tightened it up. I'm just leaning so maybe it's good like I said I really don't know how it should sound though.
Author:  dertien616 [ Thu Apr 28, 2016 10:59 am ]
Post subject:  Re: top braced Australian blackwood?
It definitely has a gong like sound to it and it has different tones when you tap different areas So maybe it will be fine.
Author:  Tom West [ Thu Apr 28, 2016 1:21 pm ]
Post subject:  Re: top braced Australian blackwood?
Your deflection testing is right in the ball park for what I would do for spruce. If you still think your bracing is too stiff, do any trimming by taking wood off the sides of your braces rather then the tops. Your only learning.....................I've been at this quite a while and believe me I'm still learning. As a matter of fact that is one of the things that intrigues me about building, there is always something to learn. Take care and all the best with the build.
Tom
Author:  dertien616 [ Thu Apr 28, 2016 8:22 pm ]
Post subject:  Re: top braced Australian blackwood?
The back is thicknessed the same and I have 4 - 6mm by 16mm tall braces on it. It sounds so much better than the top. I can hear harmonics and the sestain is so much better. So far I haven't had anything tap like this back. Do backs usually voice a lot better an have more tone. I'm thinking top definitely is overbraced.
Author:  Imbler [ Thu Apr 28, 2016 9:20 pm ]
Post subject:  Re: top braced Australian blackwood?
Until you have a lot of experience, you are probably better off going by deflection rather than tap sound. A 2x2x8 marimba bar literally rings like a bell, and it is -all- brace! I've built four classicals now, and although I tap to learn, I don't tap to dimension braces! I use deflection, previous results density, plan dimensions, etc. Someone who has built a lot successfully knows what they are listening for in -their- braced tops, but I think we (amateurs like myself) can expect a tone in a braced top that isn't there, and probably wouldn't make a good guitar if it was! It is the final sound of the guitar that is the goal, and the sound of an intermediate step like a braced top can mean something to an experienced luthier, but until quite a few guitars are under our belts, IMHO, tapping the top is mostly to educate ourselves, not dictate dimensions,
As always, in my opinion only!
Mike
Author:  dertien616 [ Fri Apr 29, 2016 7:23 am ]
Post subject:  Re: top braced Australian blackwood?
Ok so how should I do a deflection test on a braced top and how much deflection should I have?
Author:  Imbler [ Fri Apr 29, 2016 9:13 am ]
Post subject:  Re: top braced Australian blackwood?
dertien616 wrote:
Ok so how should I do a deflection test on a braced top and how much deflection should I have?


There's host of information if you put that question into the search box. Here is just one result that is quite helpful, but there are more if this leaves you with questions!

http://howardguitars.blogspot.com/2016/ ... uitar.html
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/