Re: [Harp-L] Reed slot needs to be shortened

["Doug H" <dough.harpl@xxxxxxxxx>]

I agree that in a typical situation it would make more sense to change the reed rather than the slot, but this is not a typical situation.

These reed plates are for a prototype that I am building of an experimental harmonica.  It has a full set of blow reeds and of draw reeds over 3 octaves, installed on four reed plates.  It's sort of a hybrid between a chromatic and a Harmonetta.  (I will have a website up to speed in a few weeks to explain what I am doing.)

The slots are sized to take the reeds of the correct pitch from the CX-12.  I decided to use CX-12 reeds because they are easily available and come in various keys, and I will be using screws to attach them.  A major reason why I want to have the slots fixed is so that later, as I experiment, I can easily swap out the reeds for a set in a different key, or if someone else has the thing they could make the swap without having to deal with the one odd-ball reed.

It is only 1 slot that I have to fix per harmonica, and I only have eight sets of plates in this first batch.  By the time I've fixed eight slots I'll just be getting the hang of it and wish there were more!  ;-)

Doug H

----- Original Message ----- 
  From: Zombor Kovacs 
  To: Harp L Harp L 
  Sent: Saturday, October 30, 2010 4:13 PM
  Subject: Re: [Harp-L] Reed slot needs to be shortened


  Hm. I surely don't have 100 years experience in reed design, but whenever I have 
  a length problem, I just choose a longer reed, and cut it to the right length. 
  Then I just adjust pitch with removing or adding weight. So far it worked. 
  Certainly this was only for individual reed replacements. As I understood in 
  this case we have loads of reeds so it is different. However to shorten dozens 
  of reedslots is also a lot of fuss. 

  Another way is to bolt the reeds to the reedplate with a thinner bolt than the 
  rivet itself. I have such bolts and nuts (size M1) , and they allow some 
  adjustment so the reed can be moved forward to get the correct gap settings all 
  around. In fact this may be the quickest and simplest way. Aligning the reed 
  will need some work, but it is not that bad. 



  May I ask in what way are those custom reedplates special?

  Zombor






  ----- Original Message ----
  From: Vern <jevern@xxxxxxx>
  To: Zombor Kovacs <zrkovacs@xxxxxxxxx>
  Cc: Harp L Harp L <harp-l@xxxxxxxxxx>
  Sent: Sat, October 30, 2010 7:00:41 PM
  Subject: Re: [Harp-L] Reed slot needs to be shortened

  Sadly, it is not that simple.  Filling the slot isn't the real problem.  
  Designing a longer reed having the same pitch and response as the "correct" reed 
  is.  Designing and fabricating such a reed is more difficult than shortening the 
  slot.

  Reed design involves not only reed length but the thickness profile (the 
  non-linear taper from rivet to tip.)   A reed of a given length works well over 
  only a short range of pitches.  If this were not the case, all harmonica reeds 
  would be the same length!  Below that range, the reed becomes too limber near 
  the rivet.  Above that range it becomes too thin near the tip. In fact, the 
  lengths are different for every hole.  Hohner and Seydel have had more than 100 
  years to optimize reed design.

  Reeds are made for a set of about 20 standard metric slot lengths that cover 
  four octaves from C3 to C7.    It is unlikely that you will find a standard reed 
  close to the desired length and pitch for the overlong slot length.  


  You can probably find a longer reed but it will be much lower in pitch.  Tuning 
  it up to pitch would involve removing material near the tip.  A reed with a 
  paper-thin tip will not behave the same way as a reed of the "correct" length.  
  Its response to player breath pressure would be different and it would stand out 
  from the response of its neighbors..

  It is better to adapt the slot to the standard reed than vice versa.  Otherwise 
  you are faced with the same problem when it comes time to replace the reed.

  Vern


  On Oct 30, 2010, at 3:05 AM, Zombor Kovacs wrote:

  > I donno if I understand the problem correctly, but if the slot is too long for 

  > the reed, why dont you use a longer reed instead?  Just cut it to the right 
  > length and there you have it. 
  > 
  > Zombor
  > 
  >