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| Tap Hammer Construction http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=14479 |
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| Author: | Michael Lloyd [ Sun Nov 11, 2007 8:46 am ] |
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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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| Author: | RobE [ Sun Nov 11, 2007 9:30 am ] |
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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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| Author: | Mattia Valente [ Sun Nov 11, 2007 9:39 am ] |
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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 ;) |
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| Author: | BlackHeart [ Sun Nov 11, 2007 9:40 am ] |
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Ok, but does it work, and can we hear some tap tones please! 
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| Author: | Alan Carruth [ Sun Nov 11, 2007 2:15 pm ] |
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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. |
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| Author: | BlackHeart [ Sun Nov 11, 2007 2:47 pm ] |
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So your bridge goes in before your back goes on? |
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| Author: | Dave White [ Sun Nov 11, 2007 7:42 pm ] |
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[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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| Author: | GregH [ Mon Nov 12, 2007 1:55 am ] |
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But only one wine cork in a 1000 is rated AAAA and I'm looking for that one. |
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| Author: | Steve Walden [ Mon Nov 12, 2007 2:02 am ] |
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[QUOTE=Dave White] [QUOTE=Mattia Valente] I'm confused...what's wrong with fingers? Oh, tha t dry British humor................ |
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| Author: | Mike Mahar [ Mon Nov 12, 2007 4:18 am ] |
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[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. |
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| Author: | martinedwards [ Mon Nov 12, 2007 10:06 am ] |
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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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| Author: | Michael Lloyd [ Mon Nov 12, 2007 2:13 pm ] |
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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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| Author: | jhowell [ Mon Nov 12, 2007 2:54 pm ] |
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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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| Author: | Mike Mahar [ Tue Nov 13, 2007 5:41 am ] |
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[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. |
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