I was curious how a small magnet could effect the resonance of a large anvil. 

I took a bell I made and stripped it of the handle and striker and hung it from a piece of wire. It rang quite nicely. 

I then stick a relatively large neodymium magnet to various spots on the bell to observe the results. 

You can see the progression of the magnet as I moved it down the bell

Magnet on top, no effect on the ringing.

Magnet in the middle, little change in volume, pitch and duration of ring.

Magnet on lower edge, more reduction in volume, pitch changed and ringing duration shortened.

Magnet on the end of the bell, almost completely attenuated the ringing. At that point the bell was a dead ringer.

This experiment was far from thorough, but did reveal some interesting results.

The ratio of the mass of the magnet to that of the bell is something to consider. 

The deadening effect also worked with smaller magnets on the edge, although it took two magnets to kill the ring.

I'll let you guys draw your own conclusions. 

 

Take into consideration the vibration nodes and magnet placement.

If you hang the bell from natural fibers it rings better.

I have to wonder about the effect of magnetism has, does it just cause the magnet to stick to the bell or does the magnetism itself have a dampening effect?  I would want to compare the effect of the magnet with a similar sized piece of steel attached at the same positions by welding or epoxy or super glue.  I suspect that it is the mass attached to the vibrating metal of the bell which unbalances the vibrations and dampens them, similar to an unbalanced wheel, rather than magnetism, particularly when attached to the rim.

"By hammer and hand all arts do stand."

Good point, George N. M., and excellent suggestion for isolating the variables in the experiment. I would further suggest an additional experiment with the piece of steel at the same mass as the magnet rather than its size, as steel and neodymium do not have the same density. (If you really want to be picky, don't forget to include the mass of the glue.)

8 hours ago, Ted Ewert said:

Magnet on the end of the bell, almost completely attenuated the ringing.

This makes complete sense, as the vibrations of a bell have greater amplitude at the lip than they do in the body. With anvils, some smiths report better results from putting magnets under the heel and/or the horn, where the amplitude of the ring's vibrations is greater than in the mass over the waist.

Yes there should be a node of zero vibration up at the top where the support is if the bell is perfectly proportioned and a zone of maximum vibration at the lip.  For a simple experiment, fasten a C clamp at the lip and see what that does!

To test whether or not the magnetism has any effect it should suffice to have the magnet near to, but not in contact with the bell.  One could vary the distance, up to almost touching to test that hypothesis.  I suspect no change.  the magnet touching is more or less the same as placing your hand on the bell.  Similar to damping a guitar string.

Now if the magnet is close but NOT touching the metal; then you can get eddy current braking.

Wouldn't work on non-metallic bells (e.g., ceramic or glass).

Non Metallic bells and you posting on a blacksmithing forum!   (Would depend if the ceramic or glass was conductive or not.)

What surprised me was the dramatic difference between placing the magnet on the side of the bell, right at the edge, and placing it 90 degrees on the edge. 

The mass was in almost the same place yet made the biggest net change in damping.

I have a small C clamp which I'll try out. 

Hmmmm. Now you wishing I had a steel bell and an old speaker to sacrifice. I wonder what would happen if you mounted a wired speaker magnet next to an iron/steel bell. Think you could make a bell ring to a Pink Floyd song? Attaching it to the bell would have an effect but not solely through magnetism. 

Hmmm? 

Ooooooh! the Voices just suggested another thought experiment. Suppose we were to temper a sword by passing it through an induction forge ring. Would running music to the controller cause induced changes to the temper colors in time to the music?

I think something basic as an experiment would be good for proof of concept say, "My Dog Has Fleas." Hmmmmm?

Frosty The Lucky.

It is obvious that the only proper song to use in such experiments is "Knife Edge" by Emerson Lake and Palmer!---Unless you want to go long and use "Broadsword" by Jethro Tull.

Good selections both but have you given consideration to, "Mack The Knife?" The Bobby Darin version, not the original German version, though that might work better.

Frosty The Lucky.

Is that your three cents on the question?

3 cents, ONLY THREE CENTS!?

I'll have to think about that.

Frosty The Lucky.

(Although I generally can’t stand Wagner.)

Another interesting tidbit. I turned the bell upside-down and placed a piece of steel across it. That dampened it just like the magnet did. 

You'd have to get into the physics of how the resonant wave travels within the bell to really understand why things work the way they do.  

In this case the most efficient spot to remove energy from the resonating bell is at the opening. An anvil is a different beast. 

On another note, I'm partial to Led Zeppelin myself.

 

 

I would think a couple of wraps of duct tape or latex calk around the edge of the bell would dampen the ring as well.

Anything that inhibits the vibration of the lip, really.

Frosty; it's hard to get drei pfennigs what with the Euro, (and drei groschen is even worse); so 3 pennies it is.  All complaints go to Mack!

4 hours ago, JHCC said:

Anything that inhibits the vibration of the lip, really.

Like wearing a gag?

How astute, Mack's my preferred complaint department.

Frosty The Lucky.

The pickups on electric guitars are magnets wrapped in a coil of wire that's insulated with varnish.  They are typically mounted so that the distance between pole pieces and metal guitar strings can be adjusted.  It's counter-intuitive to many novices that the pickups need some distance to work properly.  If they're a little too close, they generate weird harmonics which "flutter" under the dominant note.  This is due to the magnetic coupling/dampening working against the induced magnetic fields within the coil of wire which generate the signal.

If they're way too close, sustain suffers.  Conversely, if the pickups are too far from the strings, the attack of the note diminishes, as does the volume.  It's for this reason that most novices adjust their pickups too closely.  They notice the increased volume because it's really obvious, but they don't realize that their pickups are actively working against the rest of the instrument.

The optimal distance changes depending on the mass and tension of the string.  Larger strings generally need more distance, smaller strings need less.

Just like the bell, node placement matters.  Pickups located closer to the mid span of the string tend to have a warmer, more voice-like timbre, whereas pickups located closer to the edge of the span tend to have a colder timbre like you would get from a brass horn.  There's more amplitude at midspan than at the edge, so it's quite common for "neck" pickups to have fewer turns, lower magnetic flux, and smaller winding wire than "bridge" pickups.  This allows the musician to switch between pickups without a huge change in volume.  

 

Can you use magnetic flux for forge welding?

Naw; it fades out after the Curie Temperature.

Too bad. Might have been helpful for sticking the weld.