[TheForge] Re: triangle bells/rebar

[Mike Linn]

The physics we've been describing are valid for straight lengths of bar or 
tube. I dont think this hold for bars that are bent at 90 or 120 degrees. 
Each section will tend to vibrate independant of the others. Its 
also  vibrating at an angle to the next section and logic dictates that 
they will tend to cancel out slightly and dampen the sustain of the sound. 
Your deduction about the higher pitch makes sense also, as each section is 
shorter and thus a higher frequency. I'm guessing here.. but I figure a 
straight piece of steel will sound its tone lower and about 20 - 25% longer 
than the same length of bar bent into a triangle or square.

I too prefer the empirical methods.. but I like to know that I'm at least 
in the same ball park if not on the field..

mike

At 04:04 PM 9/19/2004, you wrote:
>I've made several four-sided dinner bells.  I use 3 feet of 1/2" round mild
>steel.  I forge points at each end and scroll them over, and make the sides
>about 9".  I say "about" because the way I hold my mouth and the phase of
>the moon seems to affect how accurately I measure things.  Then I punch a
>hole in the corner opposite the opening, and hang it from twine, leather
>thong, or whatever I happen to have handy.  A four-sided bell rings at a
>higher pitch than a three-sided one made from the same length of steel.
>That's probably a "DUH!", but I'm mostly an empiricist; I try it out and see
>if it works, then worry about the math.
>
>I've been following the discussion on nodes, half-waves, full waves, and the
>other stuff with a good deal of interest.  My only problem is I don't have
>the machinery to get that accurate.  Getting down to a 32d of an inch using
>a hammer and anvil is a bit strenuous for me.  However, I've been saving the
>emails, and plan to synopsize them later so I can make use of it when I
>retire from the computer support business, and go into blacksmithing full
>time.


            Mike Linn
      Artist Blacksmith
          McCalla, AL
        AFC Webmaster
http://afc.abana-chapter.com


"Don't worry Chief, I can stand the torture if they can stand the screaming."
                                              - Maxwell Smart, Secret Agent 86


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