dchurch
209 posts
Dec 14, 2018
7:15 AM
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I’ve worked on several harps where someone has created a slight downward bow in the middle of the reed plates. I can see the goal is to create some pressurized contact to improve air tightness.
I’m not discounting the idea. I actually did some testing using back light and the practice seems to work. For example a slightly bowed plate makes good contact by just fastening the ends down.
However if the contact surfaces of the comb and reed plates are truly flat, and there are ample fasteners, I don’t see the point.
I found some old posts about this practice and hoped I could get some current opinions on it.
Do you bow your reed plates?
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It's about time I got around to this.
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ROBERT TEMPLE II
44 posts
Dec 14, 2018
8:17 AM
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I think bowing would not help, especially when making adjustments to the reeds, ie gapping. For me, at least, I prefer a flat comb and flat reedplates when reassembling briefly to test my adjustments/gapping. To test adjustments WITHOUT the coverplates on is not a very good way to test gapping, in my opinion. Bowed reedplates mean that one HAS to secure the two plates together in order to make any tests in adjustments. Do you follow me here? I suppose one could use clamps on the ends of the harp to hold the bowed reedplates on when making reed adjustments but I find it infinately easier and faster to be able to just nest the coverplates on the reedplates in the recessed comb [much easier to work on than the sandwiched type harp, in my opinion, so far] and then make the tests. I can hold the coverplates and reedplates securely in their respective, recessed homes with my fingers when making the tests, no need for screwing or clamping the plates on. Maybe there are advantages to having bowed combs but the bow is a pain to work around if no screwing is involved and holding the bowed reedplates down with the fingers is probably not efficient at all. It would make more sense to me to have both flat comb and reedplates.
Last Edited by ROBERT TEMPLE II on Dec 14, 2018 8:26 AM
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SuperBee
5682 posts
Dec 14, 2018
11:36 AM
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I think they come, or used to com, from the factory that way. Perhaps only certain models. I stopped paying attention to an end to end bow, up to a point. Front to back bow is problematic
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florida-trader
1399 posts
Dec 14, 2018
3:38 PM
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Personally, I do not bow my reed plates. I do understand the logic. In fact, this came up in conversation at the recent Harmonica Collective in New Orleans. None other than the great Winslow Yerxa suggested that some "experts" believe a little bow is desireable. I guess it is like a lot of things - whatever works for you - do it.
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Tom Halchak
Blue Moon Harmonicas
Last Edited by florida-trader on Dec 14, 2018 3:39 PM
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nacoran
10018 posts
Dec 14, 2018
3:56 PM
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I'd never heard of doing it to reed plates, but I've heard of doing it to covers. Seems like it's a much simpler process for just covers since they aren't really a mechanical part. And you still gain some airtightness since that whole coverplate/reedplate lip is a potential place to lose air, although maybe not as important of one as between the comb and reedplate.
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Nate
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First Post- May 8, 2009
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dchurch
210 posts
Dec 15, 2018
7:53 AM
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Thanks for the response. I have the impression that it may not be a popular practice but if "experts" or others are using or accepting some bow there is nothing "wrong" with the idea.
Ditto, I have bowed a few cover plates to get them to seat tighter.
I believe some cases of front-to-back bowing on MB plates might be caused by prying the plates off the comb. I've switched to pulling the nails. The heads often get messed up but I have hundreds of spare nails and generally convert to screws anyway.
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It's about time I got around to this.
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Thievin' Heathen
1091 posts
Dec 15, 2018
8:35 AM
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I'm going out on a limb here, but I think Winslow might have been including 270 mechanics in the "little bit of bow is desirable" department. I say this because if you are putting the harp back together with the original nails into the original holes, a little bit of bow will allow the cover plate screws to contribute a little vise action.
On a couple of occasions I have (over) embossed a slot where the read plinks just fine until I screw the plate down on a comb and what slight amount of torque is introduced on the plate is enough to pinch a read. I'd say all of the old 365's I restore have bowed plates, but I don't advocate introducing any voluntary bending. Harmonicas are delicate.
For airtightness on a budget, you might try a very thin layer of Vaseline on the tines when you reassemble.
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