ADD SCREWS AT REEDS TO THE HARMONICAS by Andrés Vicente
Fixation of reeds by screws: Here we enter into a more methodical and delicate work, and it is recommended that it be carried out by expert and qualified hands, since we will remove the rivets that fix the reeds and for its new fixation we will use screws. This part is undoubtedly a very common ground for those of us who have harmonicas in our hands. Undoubtedly we will have already experienced on some old harmonicas the need for tuning of the reeds, since they are tuned with some regularity, and after a regular use a new tuning will not be possible, which will be followed by an extraction of the tongue and its replacement by a new. It can even happen to us that the tongue breaks with intensive use.
First we will disassemble the reed plates and our next job will be to release the damaged or old tab. This part that goes between square brackets is not very clear, I would write it again: [We must observe with the tongue on our top of the plate, it will have the riveted part of the rivet (and the head on the bottom of the plate), this will be the part that in my case short], although each one may have a preference or tool for rivet extraction: both filing this head and using expensive specific tools for this work are valid options, and each one will adapt to our pleasures. Once the riveted head has been removed, it is possible that the tongue is loose, which would only remove the part of the rivet that remains on the plate, which, with the help of a punch, can be pushed down, since originally this is the head of the rivet before being placed on the plate, which is conical and fits in the hole of the plate perfectly and embedded, so that it is smooth with respect to the surface of the plate, in the place where the plastic valve. If we have carefully removed the rivet, the hole will still be in the correct state, and we could also use new rivets to fix a new or recycled tongue. In my case I use screws, and then I explain how I do it.
The holes of the rivets have a nominal size of 1 millimeter in diameter, an important measure if we want to use a rivet again, because if during the previous extraction the hole was damaged, the measurement will be enlarged, with which a rivet will be a bad solution, as it will have too much slack and the tongue may not be properly secured. This case is corrected when machining the hole for a screw.
The rivet hole was drilled with a 1.25 millimeter drill bit, and I passed a male thread of Metric 1.4, with which I get a thread on the tongue plate, where I will put a screw of M1.4×3.9 millimeters long. After all the work of mechanized we must eliminate the burrs, so that later the parts that we assemble settle completely on their faces. I remember again that these screws, tools and other material, including new and original Hohner tabs, we can obtain them at http://www.harponline.de
The screw will be placed at the bottom of the plate, where the plastic valves will also be stuck and located. Thus, after threading them on the plate they will remain attached to the plate, and on the upper part, where the tongue must go, only the threaded pin of the screw will protrude. Now we must put the new tongue on the plate and on the screw. We will see that the tongue has a hole of 1 millimeter, since they are made to use the rivets, but in this work its diameter should be modified to 1.4 millimeters, and it should not be higher to avoid gaps that produce a malfunction.
For this I will use a small file called “mouse tail” of round profile that we usually use in the companies of the sector and we can also obtain in http://www.harponline.de. I will use the 1.4 mm diameter, which will leave the hole in the tongue in its proper measure. I take the tongue between two fingers and carefully pass the file through the hole filing it until I see it entering through the screw shank, always observing that it must fit very well and sit well on the plate, having previously removed the burrs from the previous machining in the plate, because if the tab does not seat its top correctly on the plate, it will not vibrate properly.
Once put the tongue, we put the nut that will fully fix the screw with the plate and the tongue, after which we proceed to align it, put a light behind the plate and correct its position until it is perfectly aligned with its slot, checking that can vibrate freely through your interior. For this we will push it inwards observing that it does not rub between the faces of the housing.
After this we can make sure that the nut does not loosen, and although tightened with a moderate force should not loosen, although we can use some soft thread fixer, such as nail polish; a small drop on the thread will prevent it from loosening. Now we must proceed to fine tune it. For this we must use a chromatic tuner, sound the tongue independently and observe its tone in the tuner.
To correct it we will put a steel sheet between the plate and the tongue so that it is fixed when we work on it. If the tone observed in the chromatic tuner gives a low tone, towards the lower or flat note, we will file with a small file or “mouse tail” flat on the tip of the tongue, and if the note is high, approaching the next one top note or sharp, we must file in the near part of the fixed base of the tongue, closest to the screw, which will lower the note. It is very important to practice first with an old harmonica, because this is a precise task and requires practice and learning, since the filing necessary to modify the tone and obtain the final result of a correctly tuned tongue in your note is very slight.
The work is almost finished. We only have to put and stick a new plastic valve on the bottom of the plate, just in the face where the screw head will be. As the head of the screw takes up space, the valve will not adjust correctly, since it was initially built to place it on a flat surface where only a small part of a rivet protrudes, so for its correct position.
I cut with a die a small circle (more like a half circle) at the end of the valve, so that it fits together with the round profile of the head of the screw, after which I add the glue and put it in its correct position. Well, after this work, and in my case I have done in some sets of complete plates, I have put all the new tabs, all fixed by screws, and in the photo you can check the appearance they have ended up having. As the plates that I used were very damaged, after the work of holes and threading, just before starting to put the tabs, received a cleaning by sandstone and then I gave a silver plating, in a matte finish after a subsequent “rodenado” for a longer life of the plating, and a nice contrast of colors. Apart from this aesthetic, the plating has a very important mission, since when adding material by means of the plating, the holes where the tongue works are reduced It is its dimension. This can cause that the tongue can not even vibrate, but just by filing VERY carefully we will leave the slot in its measure, that if, leaving the minimum space possible to have the most accurate setting, to avoid the slightest air leak. Originally the slot has a thickness of 2.20 millimeters wide and the tongue 2 millimeter wide, these two tenths of slack is what we should have at most, and at least just enough to allow the tongue to vibrate.
The resulting harmonica works perfectly after this modification and restoration, and I have to indicate that I have done this work after what I learned in the above-mentioned websites of Franz Chmel and harponline, where all the work to be done is exposed very detailed and extensive. These places have served me for my learning and for the work that I currently do with my chromatic harmonics, and therefore I recommend your visit, although we will have to read them in a different language, and an online translator will be able to help us.