Re: [Harp-L] Altering reed slots


On Aug 10, 2010, at 11:18 AM, captron100@xxxxxxx wrote:



Re the need to shorten a reed slot, Vern wrote:
- Install the short reed in the too-long slot with no gap.

This I didn't understand? If the reed is too short, there WILL be a gap?

- Cut about .050" of the slug off of the tip of a long reed.

Ok, this I DO understand and is what I do. I usually take a longer (lower pitched) reed as a replacement, cut it shorter, take off some weighted tip (if necessary), and then retune the reed. Usually UP. I almost never tune a reed down. I may use solder on the tip of a reed but I never use it on the rivet end. It deadens the reed.

- Stick it and a .001" plastic shim in the slot and against the tip of the reed
with tiny dabs of wax on each side.
- Glue it in place with epoxy or soda-filled super glue.

In other words, you are not using the rivet nor aligning with the rivet holes. Ok, this seems plausible but the reed woud have to be only 'slightly' shorter than the slot.

- File flush with the surfaces of the plate.

?

What with the existence of many different lengths of reeds from the various manufacturers, I think this thread IS indeed relevant on harp L.

Ok, I don't think it is, but I'm willing to fly with it. Most people aren't going to need this stuff.

Iirc, a couple of years ago Dave Payne proposed what he said was a simple way to shorten a slot. Tho i didn't understand his instructions I didn't ask for clarification.

ANY thing used to shorten a slot will have to be hard shelled. The sound has to vortex off the tip of the reed, so the air splitting surface should be sharp and stable to give best results. Rounded edges won't do. This is why I have always advocated punching reed plates and then slurry honing the entry side to remove the entry cuts. Experiment: slice a piece of cheese with a knife. The entry side will be squeezed BEFORE the knife enters the cheese and leave a rounded entry point. Using a sharper knife will lesses this. Ergo, reed punching dies should be changed out frequently enough to keep the slots sharp..OR honing is the answer. Honing is another step, so is not used.

Now I am having trouble understanding Joe's suggestion re using a brass screw.

Using a brass screw is similar to bushing out a rivet hole. What you are doing is adding a screw to the end of the slot, and in effect shortening it the dia of the screw. The threads hold it in place. You file the top and bottom flush with the plate. You now have a slug inserted. You now file from the open part of the slot taking away as much brass slug as necessary to reach your goal. Lets say the slot is .10" (abt 2.5 mm) wide. You would use a 1/8" (abt 3 mm) screw. Now lets say your reed is 2 mm short. That's a LOT. You can file about 2 mm give our take OUT of the screw and still have 1 mm of 'meat' holding the screw in place.

This is EXTREME work and only justifiable under extreme cases. Me? I would prefer to use a longer reed and NOT try to shorten a slot. In fact, I usually lengthen slots. Using a knife edge file and then a square file.

I like the idea of lengthening the reed to fit the slot but wonder if this method would be viable due to the flexibility of the new reed being so drastically altered; also, how drastically would the new reed need to be re-tuned?

I agree. I don't like the amount of ramifications involved. BUT a good set of hands with a good head behind it could do it. I usually classify these types of modifications under my 'Because I CAN' file. But honestly, in this day and age, it is usually better to just go with a new reed plate. Back in the old days, we didn't have much of a choice and if you didn't do your own mods, it could cost you a small fortune to even play. And most mods were on chromatics because of the cost. Diatonics were generally a disposable item.

What is "soda-filled super glue" - a mixture of super glue and baking soda, to thicken the glue so it won't run?

No, soda filled means the gas that is in the glue. Then when activated in the air, the sudden rush of nitrogen to the resin, causes heat and that sets the glue. I don't remember what gas it is but maybe Argon? This is why some super glues don't keep and once used, you may as well toss the tiny tube away.

Ron










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