Tapping boards!

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Petecane
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Tapping boards!

Post by Petecane » Mon Mar 04, 2019 3:06 pm

Whilst in the Military " Tapping Boards " meant that I was in serious trouble!.
However on the Luthier side of things it has a different meaning.
I have read that violin makers tap their boards to get a certain note?
I am currently thinning down a Cedarwood sound board ( Top ) for a Soprano Uke.
It definately has a note when I tap it and crystal clear.
No doubt about that although I am very deaf to human speech.
I can hear " note pitch ".
I am very probably going OTT here but does the Top sound board have to be thinned to ring to a certain note?
Do any instrument's boards have to be thicknessed to ring at a certain pitch?
If this is so then logic tells me that the "back " will also have to be thicknessed to a certain pitch to bounce back the sound to the reverberating top sound board?
This is my understaning of how a guitar responds.
And then we brace them which throws a whole different angle to it and quite literally as the sound board is now not in it's pure state.
I think the answer to my question is, and hopefully, .....I am going too deep?
I have also read about luthiers who do not use calipers to thickness their boards.
They have said that calipers are of no use because they can "feel" which is right or wrong.
But.....that theory goes straight out of the window when it comes to CF Martin mass producing ( in my view ) outstanding quality instruments ( both ukuleles and guitars)..........Martin D28?.....the Uke series.
...I don't think he ever made a bad one!
And also Gibson!....J45?.....superb....board tapped?.... probably not!)
So board tapping!
Where are we with this?
Is it Necessary?
Is this Hocus Pocus?
Is this to the protection of the Luthier that does not recommend any body trying the art themselves as it will be beyond them to dare and a threat to their livlihood?
I would very much like your honest opinions please.
Many thanks for hearing me through.
Pete

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peter.coombe
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Re: Tapping boards!

Post by peter.coombe » Mon Mar 04, 2019 5:24 pm

Read the Gore/Gilet books. All is explained there.
Peter Coombe - mandolin, mandola and guitar maker
http://www.petercoombe.com

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lamanoditrento
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Re: Tapping boards!

Post by lamanoditrento » Mon Mar 04, 2019 5:30 pm

peter.coombe wrote:
Mon Mar 04, 2019 5:24 pm
Read the Gore/Gilet books. All is explained there.
+1
Trent

Petecane
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Re: Tapping boards!

Post by Petecane » Mon Mar 04, 2019 7:18 pm

I don't have them but thanks any way.

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kiwigeo
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Re: Tapping boards!

Post by kiwigeo » Mon Mar 04, 2019 9:08 pm

Unfortunately that's not an acceptable excuse for not having them :mrgreen:
Petecane wrote:
Mon Mar 04, 2019 7:18 pm
I don't have them but thanks any way.
Martin

Petecane
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Re: Tapping boards!

Post by Petecane » Mon Mar 04, 2019 9:28 pm

Ha ha...okay you win

What do I look for?.
I mean how many books are there and where can I get hold if them?
Pete

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56nortondomy
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Re: Tapping boards!

Post by 56nortondomy » Mon Mar 04, 2019 10:33 pm


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kiwigeo
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Re: Tapping boards!

Post by kiwigeo » Mon Mar 04, 2019 10:34 pm

See here: https://goreguitars.com.au/main/page_th ... _book.html

If you ask Trevor he'll sign the books for you which means when he dies they'll be worth a mint :mrgreen:

Petecane wrote:
Mon Mar 04, 2019 9:28 pm
Ha ha...okay you win

What do I look for?.
I mean how many books are there and where can I get hold if them?
Pete
Martin

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Mark McLean
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Re: Tapping boards!

Post by Mark McLean » Mon Mar 04, 2019 10:47 pm

Another vote for the books (2 volumes).

Although it is lovely to tap a piece of cedar or spruce and hear a musical sound, at that stage in the process it is fairly meaningless (IMHO). By the time you joint it and brace it and then glue it to the rims and then attach a lump of hardwood (bridge) on the front - everything changes. What is more important than sound is stiffness. Get a good sense of whether this piece of wood is stiff or floppy, along the grain and across the grain. Then you start making decisions about how thin it should be and how heavily to brace it according to that initial characteristic.

There is a lot more that you can measure as the process goes on - deflection testing (stiffness again), modal frequency, chladni patterns. All of these have a good scientific rationale and can guide your building (and all is revealed in the books). The tap tone is a lot more subjective and unmeasurable. And many of us have had the experience of an initial piece of wood that has a tap tone like damp cardboard until you brace it, and then it sings.

I hope we don't sound like a bunch of cult members talking about these mystical books. It is just that Trevor Gore has actually worked out some important stuff about how guitars work, and Gerard Gilet really knows about how to build - so their books are a major advance in our craft. And written here in Australia so we are pretty keen on them

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TallDad71
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Re: Tapping boards!

Post by TallDad71 » Tue Mar 05, 2019 6:46 pm

That the board has a musical quality at this stage is enough. Some boards you pick up will thunk, they will have a low level of musicality.
Use an app like FFT to record the tones that your board makes during different processes, separate boards, glued, braced, boxed, bridged, finished.
You will create a record of what is happening to the musicality of the instrument.
Since your UKe has many vibrating/oscillating parts the relationship between tap tone and finished timbre is multifactoral and difficult to map intuitively.
Eventually you will start to get a feeling.
Alan
Peregrine Guitars

Petecane
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Re: Tapping boards!

Post by Petecane » Tue Mar 05, 2019 8:06 pm

It is the "feeling " part of it that may be about the limit.
Multifactoral is a good description as there is no black and white answer I can fathom.
With reference to " the books".
I am finding the decision to get them extremely hard.
I have read some in depth reviews about them and they are no doubt very informative, in depth and thorough.
It must have taken thousands of hours to put the two volumes together but..........
I do not now, or in the future want to build a guitar.
So I feel a lot of the text there may be wasted for my wants as it is geared towards making guitars with completely different bracing concepts to that of a uke and a different animal to the uke.
I will simply not understand the maths therein and neither do I want to be involved with that.
It is too complex for me and on another horizon that I do not and cannot understand.
When I am faced with overwhelming data, info like this I get scared and down tools as the whole idea of making a musical instrument becomes so much of a challenge, so much beyond my skills that I end up totally confused by it.
I do not want to design a guitar or change what has been going on for decades with Uke making.
I want to build soprano ukuleles much in the way to Ken Timms.
I work from a Grellier drawing of a Martin soprano uke.
The top and bottom boards have two braces each.
It is simply a folk instrument and the design is proven.
But although tiny in size I have heard some serious classical pieces played on the soprano uke by John King.
It is a simple instrument and I want to keep things simple.
But in the right hands this simpleton gets massive!
Maybe I should not have asked about tapping boards because I think the answers will be too complex for my simple brain.
To say that a good board rings to some kinda sound when tapped will be about it for me.
Like said, when braced and all glued up it is a different ball game anyway.
I do not aspire to make better ukes than CF Martin but if I can come up with something that sounds pretty close, goal achieved.
I do not know if he employed a board tapper to sift out the duds?
I do not know.
I think I will have to stay with my gut feelings of " I do not know" and just keep trying and bluffing my way through a board tap until one day it all becomes clear........
Or probably in my case....NOT.
Some of the instruments I have seen on this forum are beyond belief with the standard of craftmanship.
I am truly Wowed!

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peter.coombe
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Re: Tapping boards!

Post by peter.coombe » Tue Mar 05, 2019 10:47 pm

Any music instrument with a wooden box and strings follows the same physical principles. Those principles are outlined in the books. The frequencies will be different for different types of music instruments, but the principles remain the same. Apply the principles and you will most likely end up making much better sounding instruments, no matter what type of instrument you are making if it has a box and strings attached. It does not have to be a guitar, although the books are oriented at guitars. I have done just that with mandolins. Your excuses don't cut it with me. You did ask and were given an answer, but you don't like the answer. Why ask if you won't accept the answer.
Peter Coombe - mandolin, mandola and guitar maker
http://www.petercoombe.com

Petecane
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Re: Tapping boards!

Post by Petecane » Wed Mar 06, 2019 8:11 am

Hey Peter.
Thanks for your reply.
I was not aware that the books applied to any stringed instrument or that they cover simple bracing systems a la a Ukulele.
I thought that they were geared towards the guitar plans within and therefore the tap frequencies would be different to that of Ukuleles etc etc.
In short...
15 minutes ago I placed an order for " The books".
Thank you for making that clear to me.
Is there a lot of maths involved in transposing the frequencies and other criteria to mandolins and smaller instruments?
I dare say if I get a problem then someone here can help me with it?
Have a good day.
Pete

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lamanoditrento
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Re: Tapping boards!

Post by lamanoditrento » Fri Mar 08, 2019 10:03 am

As others have said, the books provide principals that apply to more than just guitars. You don't need to understand all the math to understand the principals. The math is there to prove an show what underpins the principal in case you want to test them. Which I believe has been done a number of times and hasn't resulted in any challenges to the principals.

Also, while the build volume shows a guitar process, it is dense with practical approaches to building and woodworking that can be applied to other instrument making, including ukulele, bouzouki :wink: and other instruments.

There have also been some great discussion about applying the methodology to other instruments on this form, for example viewtopic.php?f=1&t=4312&hilit=falcate+ukulele#p50920
Trent

Petecane
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Re: Tapping boards!

Post by Petecane » Fri Mar 08, 2019 3:26 pm

A huge thank you to all that have replied to my question.
I only now know what you mean by read " The books".
My books arrived today.
I am truly blown away.
I have only flipped through the pages and they have left me very humble.
........in fact I am so wowed by my ignorance.
I can now understand what you mean by " read the books ".
You were all to the point but I did not comprehend what was meant exactly by " The books".
I suppose it was impossible for you all to answer my question without going into pages of physics so you summed it all up by saying " read the books ".
Please understand that at the time I did not know what you all were talking about...." the books "????
I now know what you all mean.
These books are a masterpiece in physics and Lutherie.
I am bloody gob smacked mate!
The Aussies have done it again.
Proud or what!
.....I am confident that in the future these two volumes will be come to be known as " The books" worldwide.
It is verging on that right now.
Hell... what an achievement.
Pete

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