Slow Food Concertina Making,5

[chris salty-dog vonderborch]

I am well into the laborious but interesting (and yes, exciting) process of making the reeds for the baritone. The count is now 14 out of 96. Also, my former skill level (such as it is) is returning. I have made around 300 reeds in past years, for former projects, but the last was 3 or so years ago, so now I feel I am back into filing practise...a reed fitted and tuned, to close tolerance, in half an hour (sometimes).

 

If my computer skills are up to it, I will attach a photo of my "precision" shoe-filing jig. What I have been doing is to use the jig to true up the slot and its several degree downward relief. I find that the jig, which the photo will show to be largely self-explanatory,produces a perfect slot, using a dedicated file which has been thinned down appropriately on its back side. The file has a nylon block attached, which essentially slides along an adjustable platform.

 

The brass shoes were produced by a CNC milling set-up, and the slots were initially parallel-sided into the slot. So first, I blacken the slot with texta, and clamp it in the vice. I then carefully file the slot until I get a knife-sharp edge, similar to what I have observed on some well-known concertinas. I then clamp a piece of reed steel (old surveyors measuring "chain", in fact) in the vice, and file one edge perfectly flat by filing along the steel...not "draw-filing". I then turn the reed steel over in the vice, and I find that I can file the taper quite accurately with practise. I maybe make one or two slight adjustments, then I check it in the shoe, using a head magnifier or, sometimes, a binocular microscope (thanx, Chris Ghent!!). Then I file the desired profile, starting at the tip to get it to the desired thickness, as per studies of reeds from well established instruments. Then, of course, tuning!! Nothing surprising there!

 

One thing that I THINK I have noticed, tho' it could be a subjective observation, is that the new reeds sound better after resting, or being exercised, for a couple of hours after filing. This could be imagination, but my feeling is that it is real. Maybe Dana could shed light on this?? Doed the steel relax???after stressing??? I will leave it there.

[Jack Bradshaw]

It's probably not the bulk of the steel relaxing, but a change in the surface stress due to initial oxidation after filing....

[Dana Johnson]

One thing that I THINK I have noticed, tho' it could be a subjective observation, is that the new reeds sound better after resting, or being exercised, for a couple of hours after filing. This could be imagination, but my feeling is that it is real. Maybe Dana could shed light on this?? Doed the steel relax???after stressing??? I will leave it there.

I wish I could shed some light on this. Reed steel does develop tensions when manufactured that are balanced until half the steel is removed from one side while filing. The vibration of playing gives these stresses a chance to equalize over time. ( common practice in manufacturing of certain metal parts is to subject them to strong vibration for a while to de-stress them. ( they also tend to de-magnetize ) That this happens in new reeds I do not doubt, but as to how it affects the sound, I'd be shooting in the dark, and I don't have night sights. Perhaps eventually one of us will figure it out, but it is worth noting that the experience is a common one for reed makers.

Dana