magnetic card stock for weighting reeds

[wunks]

I need a low Eb for my Wheatstone Jeff duet.  I've had great success with bi-sonoric reed pairs but I don't wish to use solder on one of the low F's.  I've discussed with Bob Snope having a cluster of spares  ( Eb, E, F#.G# ) to pop in and out as needed,  But He didn't have any of these when he worked on my box.  I'm wondering if magnetic card stock or sheeting would work for weighting.  It would be easy to apply and remove and easy to tune.  Thoughts?

[fred v]

I'm going to guess that it would fall off with the vibration. That magnet card stuff is so weak.

[Jake Middleton-Metcalfe]

if you can find a magnet strong enough it may stay on but although I have not personally experimented with this: I was warned during my training about the dangers of reeds becoming magnetized and it apparently can cause unwanted acoustic effects ... though I do not remember what those were exactly.

[Clive Thorne]

A magnet (e.g. a magnetised reed) passing by a conductive material (e.g. a reed shoe) will induce an electrical current in that conductor (an eddy current), taking energy from the reed and hence damping and slowing down the movement. I.e a quieter and flat note.

 

I say this based on basic physics, not from any experience of magnetised reeds.

[wunks]

6 minutes ago, Clive Thorne said:

A magnet (e.g. a magnetised reed) passing by a conductive material (e.g. a reed shoe) will induce an electrical current in that conductor (an eddy current), taking energy from the reed and hence damping and slowing down the movement. I.e a quieter and flat note.

 

 

Either of which could be considered desirable in this case.

 

An easy and seemingly low risk experiment I reckon.  I'm about to give up on the damn tractor 'till spring....😏

[alex_holden]

I deliberately demagnetise reeds while tuning them because otherwise they can collect a 'fur' of fine steel dust along the edges that interferes with the free passage of the reed through the frame opening.

 

I've heard of people experimenting with Blu tack (the sticky putty you use to put posters on walls). How about a drop of sealing wax? Should be fairly easy to clean off if you change your mind.

[wunks]

5 hours ago, alex_holden said:

I deliberately demagnetise reeds while tuning them because otherwise they can collect a 'fur' of fine steel dust along the edges that interferes with the free passage of the reed through the frame opening.

 

I've heard of people experimenting with Blu tack (the sticky putty you use to put posters on walls). How about a drop of sealing wax? Should be fairly easy to clean off if you change your mind.

Good point.  I'm picturing the Etch-a-Sketch guy with a big beard... although I don't know where the steel dust would come from?

 

Someone here mentioned nail polish not too long ago.  I wonder if any of these would be heavy enough for the drop from F to Eb.  Might work for the F#, G# though.  The advantage of the mag-tab would be to label them after tuning and have a batch at different pitches.

[alex_holden]

22 minutes ago, wunks said:

Good point.  I'm picturing the Etch-a-Sketch guy with a big beard... although I don't know where the steel dust would come from?

 

Yes, it did look a bit like that under the microscope. The dust comes from filing the reed while tuning it. If the reed is magnetic you'll probably never get rid of it all.

[ttonon]

 

https://turboharp.com/collections/the-turboslide-series

 

 

 

[RogerT]

Curious as to why you don't want to use solder? It's an easy effective solution and is reversible.

[wunks]

3 hours ago, RogerT said:

Curious as to why you don't want to use solder? It's an easy effective solution and is reversible.

It's complicated but the short answer is that this particular instrument ( Wheatstone Jeff duet )  is chromatic throughout the violin, viola and cello range, down to the low cello F, except for the #'s mentioned above.   Having the option for the lowest cello notes, especially Eb would allow playing lots of beautiful classical music.  I would like to be able to change combinations of notes at this low end to accommodate different keys and/or pieces.  Having spare reed assemblies to pop in and out would be great but the mag-tab Idea ( if it works ) would be even quicker ( and cheaper ).

[RogerT]

Ah right. A temporary solution.

[wunks]

Yes but maybe a flexible solution better describes it;  chromatic down to Eb with quantum assist.

[RogerT]

I've got a load of tiny…i mean really tiny (like 2 or 3 mm diameter) magnets. They would be ideal to try out your idea. You can get them for very little on eBay. You may find that fine tuning is the issue…if they stay put with the reed oscillating. If i get some time i might experiment myself…I'm now curious to see if this works.

[wunks]

I think rods wouldn't stick as well ( less surface area ) and flat stock would be easy to trim for tuning.  A search turns up high mag strength stock, different thicknesses and one side adhesive.  I think i'd approach it this way:

 

-Use a low reed from a donor box and test everything therein after twang-testing by ear to get close.  

-Try for a half tone first and if successful, add more weight either with another mag-tab or a different material if using       adhesive backed stock.

-In my situation, a half tone would be enough if I find a suitable E reed.  I could then have Eb, F# and G#

 

I'd give the target box a good air cleaning and start with the A/G# pair with the sharp on the draw.  Ditto for the G/F# pair.  

F to Eb might be a stretch so I think I'll hold out for an E reed.

 

I think it's worth a try and not too difficult an experiment.  let me know if you do try it, and any other ideas are welcome!

 

 

[d.elliott]

A Couple of thoughts with respect to a magnetic tip weight:

• The speed that the reed tip is moving at, then stops then starts again twice for each cycle means that the dynamic forces in terms of momentum etc will be very high relative to any magnetic adhesion.
• when you tune a reed you are often filing off micro milligrams of material, you need a way of ensuring any removable fix can go back to exactly the same place along the length to ensure the weight to centre of reed flex  stays constant
• The reed tongue's side to frame vent's side wall clearance is very tight, any shifting across the reed will cause the reed to stop or shed it's weight. 

I think that your initial idea of changing out a reed when you  need to set up would work best 

[ttonon]

4 hours ago, d.elliott said:

A Couple of thoughts with respect to a magnetic tip weight:

• The speed that the reed tip is moving at, then stops then starts again twice for each cycle means that the dynamic forces in terms of momentum etc will be very high relative to any magnetic adhesion.

How do you know what the comparison between the dynamic forces and the magnetic attachment forces on a piece of magnet will be?

 

We do know that if the magnetic pieces are small enough, their magnetic forces are more than enough to keep them on the tongue. As Alex mentioned, there can accumulate a magnet fur on a tongue that stays there during vibration. 

 

My guess is that the ratio of dynamic force to magnetic force increases as the size of the magnetic particle increases, because the dynamic forces scale with volume/mass and the magnetic force scales with surface area contact to the tongue. But this doesn't say anything about whether a given magnetic piece can cause a desirable change in pitch and still remain on the tongue. Here, we need to experiment. 

4 hours ago, d.elliott said:

• when you tune a reed you are often filing off micro milligrams of material, you need a way of ensuring any removable fix can go back to exactly the same place along the length to ensure the weight to centre of reed flex  stays constant

I don't know if it's really a billionth of a gram as you suggest, but it may not be too difficult to put the magnet back in the same place, if you check the pitch with a test run. 

4 hours ago, d.elliott said:

• The reed tongue's side to frame vent's side wall clearance is very tight, any shifting across the reed will cause the reed to stop or shed it's weight. 

I'm not clear on what you mean by "stop or shed its weight." But I do see perhaps a complication if the magnet is placed in a different place off center on its short dimension. The possibility of slightly exciting torsional modes might complicate matters. 

 

My gut feeling however is that such torsional vibrations aren't much of a threat. Again, all we have to do is experiment. 

 

Best,

Tom

 

 

4 hours ago, d.elliott said:

 

 

[wunks]

Aye.  Proof's in the puddin'