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Hi,

The rubber wine corks can make an excellent lightweight tap hammer for those looking to venture in the tap tone world. Here I used ?” dowel 8 ?” long and pre-drilled both the cork and dowel end to accept a #8 - 1 ?” screw. The #8 screw seems to add just the right amount of weight to the hammer’s head. The dowel end was also shaped to the circumference of the cork to restrict head movement.



Traditional cork can also be used.



Regards,

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Michael Lloyd

“I was born to ignorance, yes, and lesser poverties ...
I was born to privilege that I did not see ... I didn’t know it, but my way was paved” – John Gorka

Michael,

This is a really cool little tool that us beginning luthiers (such as me) love to see. It is simple, easy to make, and has a great use. Thank you very much for sharing.

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-Rob Eckert
Ann Arbor, Michigan

I'm confused...what's wrong with fingers?

Then again, they teach us percussive techniques in doctor school, so I may have an undue leg up ;)

Ok, but does it work, and can we hear some tap tones please!

A soft hammer will damp out a lot of the high frequencies. This is nice if you're trying to hear the main tap tones. For spectrum tests I use a 5/8" or 3/4" diameter hardwood or hard plastic bead, and tap on the bridge saddle. It sounds a lot worse than it is.

[QUOTE=Mattia Valente] I'm confused...what's wrong with fingers?

Then again, they teach us percussive techniques in doctor school, so I may have an undue leg up ;)[/QUOTE]

Mattia,

So you use your leg as well? This calls for a photo tutorial

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

But only one wine cork in a 1000 is rated AAAA and I'm looking for that one.

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GregH
Fot Wuth

[QUOTE=Dave White] [QUOTE=Mattia Valente] I'm confused...what's wrong with fingers?

Then again, they teach us percussive techniques in doctor school, so I may have an undue leg up ;)[/QUOTE]

Mattia,

So you use your leg as well? This calls for a photo tutorial [/QUOTE]

Oh, tha t dry British humor................

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Steve Walden
Aspiring Builder,
Bartlesville, OK

[QUOTE=BlackHeart]

So your bridge goes in before your back goes on?

[/QUOTE]
The spectrum tests happen after the guitar is assembled and are a way of documenting certain aspects of the sound of the guitar. It is not used for tuning unmounted tops.

Tapping a sound board is a pretty neat thing to do. It turns out that tapping something will cause it to radiate at every resonant frequency that it is has. You can then do a spectrum analysis using a FFT. This pulls out all the individual frequencies that make up the the sound and displays their amplitude. The upper limit of frequency is determined by how long the hammer is in contact with the sound board. That is determined by the hardness of the hammer. Soft rubber or plastic will damp out a lot of high frequencies. A glass hammer will damp out only very high frequencies. The high frequencies can interfere the analysis that you are trying to do so a soft mallet is often best.

A Doctor's reflex hammer might be a pretty useful tool for this but I like the wine cork idea too.

I have a full set of piano hammers from a 1930s german piano I dismantled a while ago looking for useable wood......

Haven't used any yet......

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My soundclick xx luthier blog xx luthier soundclick

You’re welcome Rob.

Guys, I also use my knuckle at times, which brings me to Alan’s point “A soft hammer will damp out a lot of the high frequencies. This is nice if you're trying to hear the main tap tones.” I’m definitely hearing the difference in the sounds with the different hammer materials rubber, cork, wood and knuckle. I suspect that some of that sound is being given off by the hammer itself especially the more denser the hammer material. I just don’t understand the science behind the frequency separation and the instruments used to determine those frequencies but I’m willing to listen to anyone willing to share those thoughts.      

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Michael Lloyd

“I was born to ignorance, yes, and lesser poverties ...
I was born to privilege that I did not see ... I didn’t know it, but my way was paved” – John Gorka

Very interesting thread.  I'm using a piano hammer in an X-Acto saw handle.  My unschooled thoughts were to get consistency and not do physical damage (denting) to the top.  I was (am) pretty clueless about the dampening issues.  In another display of cluessness  is FFT some kind of fourier transform?

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Jim Howell
Charlotte, NC

[QUOTE=jhowell] In another display of cluessness is FFT some kind of fourier transform?[/QUOTE]
Yes. it is the Fast Fourier Transform that is used in almost all computing where complex waveforms are analyzed. Some super computers are highly optimized to perform the FFT operation. Although, now-a-days, a good PC has better performance than specialized dedicated FFT machines did just a decade ago.