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Lachenal reed frame flatness


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I've been cleaning up some rusted reeds and reed frames and decided to use a file rather than glass fibre pencil to clean up the underside of the frames and remove the rust spots from the clamp screws.  I noticed that the frames don't appear to be flat, with a significant dishing towards the root of the reed (on the attached photo where the reed hasn't been cleaned by teh file) .  I've noticed in rebuilding that some notes appear to pass a lot of air and am now wondering if this might be the reason - air passing underneath the frame rather than through the reed - and also wonder whether anyone else has seen this?

 

This is a Lachenal reed - I've noticed that Lachenal reed frames tend to be slightly thinner than others but I haven't looked at other makers' reeds flatness to see if the result is the same

 

Alex West

IMG_4810 (1).jpeg

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as long as there is no significant air escape around the frame, I would not worry about it. You can do more harm than good by trying to get back to a 'flat'surface'. I would guess that most frames relax like this after machining. 

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4 hours ago, Alex West said:

  I've noticed in rebuilding that some notes appear to pass a lot of air ..

 

 

In the case of Lachenal reeds I find this us usually a result of rather wide clearance between reed tongue and frame.  Easy to check with a 10X lens.

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Were it a cylinder head of comparable age - which I appreciate it isn't - you would put some wet & dry on a sheet of plate glass and fettle it flat - probably aided  by some Engineers 'Blue'.  Of course if you did that you'd almost certainly have to shim the slots.  

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what model of concertina was it off? Was it one of the mahogany ended ones? I have heard it suggested that on those instruments they just pressed out the frames and didn't bother fettling, flattening or squaring up the slots at all on the more basic mahogany instruments. You do have to flat them off on the bottom at least when they are pressed out, its done that way in the Wheatstone workshop to this very day. 

Edited by Jake Middleton-Metcalfe
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Thanks all for your comments.  These particular reeds are off a basic 20 key instrument so it could well be that they haven't had any "after-pressing" attention.  I wouldn't have thought I'd need to shim the slots - I'm not touching the sides so the angles of the "wedge" remain the same although the reeds might sit very slightly lower in the slot.  These reeds are going into the "spares" box so if I use them in anger, I may have to modify the slot anyway.

 

I'll check the clearances on the particular reed that seems to be passing air, Theo. That's a good observation

 

Alex West

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In the harmonica world, Rick Epping has pioneered a technique of burnishing or embossing the reed frames to close up any unwanted gaps and improve the performance of the reeds.  There are lots of youtube videos on how to do this, and there are even speciality tools on the market for folks to do their own reed embossing.

 

Has anyone tried this technique on concertina reeds?

Edited by Don Taylor
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I've just been working on a top quality Lachenal and the underside of the reeds all have marks that suggest they have been filed flat after assembly.

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On 5/3/2020 at 6:17 PM, Don Taylor said:

In the harmonica world, Rick Epping has pioneered a technique of burnishing or embossing the reed frames to close up any unwanted gaps and improve the performance of the reeds.  There are lots of youtube videos on how to do this, and there are even speciality tools on the market for folks to do their own reed embossing.

 

Has anyone tried this technique on concertina reeds?

 

Embossing is really only needed with riveted reeds, like harmonica or accordion ones. With tapered, and clamped/double-screwed, concertina reeds you can cut the tip off the reed tongue and slide it up in the slot to fit better.

 

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2 hours ago, Stephen Chambers said:

Embossing is really only needed with riveted reeds, like harmonica or accordion ones. With tapered, and clamped/double-screwed, concertina reeds you can cut the tip off the reed tongue and slide it up in the slot to fit better.

See this video at about 1:30, he is embossing the edges of the slot, not (just) the end.

 

and this video from Brendan Powers about how he uses a nail varnish painter to close the gap at the sides at the root of the reed and also to counter any hump in the reed at its root:

 

Edited by Don Taylor
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That pattern of “dishing is caused by the actual bending of the shoe crosswise against the reed tongue.  Those small screws can exert a surprising amount of force.  I once used .063 hard brass for my reed clamp blocks, but found they actually bent visibly  over the reed.  The .093” I use now doesn’t bend appreciably, but the reed frame does slightly bend up at the screw end so I always flatten them after reed mounting.  
   If the reed shoe fit  before you cleaned it up, flattening with s file will make it thin enough to need to slide farther forward in the dovetail and you may not have room to move it forward and will need to shim.  Given that dovetail mounted reeds will seal on their side edges. As long as they are touching at the tip and base end, there isn’t much place for the air to get in.  Yours seems to be ok at those locations.

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You're dragging this thread seriously off-topic Don Taylor, but isn't it apparent enough, from what I wrote, that I do know what embossing is and why, and how, it is done with harmonica reeds today? I've known Rick Epping since he had his repair workshop in Spiddal, almost 40 years ago, and I know Mick Kinsella too - I don't need to watch a video about it.

 

I'm also aware of the somewhat similar practice of "coining" or "chiselling" practiced by Italian, and other, accordion reed makers for many years.

 

Here's a previous discussion we had about it: 

 

And here's a thread that I initiated over on melodeon.net about it: 

 

http://forum.melodeon.net/index.php?topic=20754.0

 

I've been repairing, and tuning, concertinas for 50 years this year, and I can see no benefit in using such techniques in concertinas with English-style construction, which have tapered reed tongues that are easily removed from their frames for adjustment or replacement - so that you can make the tapered reed wider in its tapered slot by cutting a small amount off the tip, and sliding the reed forwards. But I will ask Rick what he thinks about using embossing on them, and report back on that (in a fresh thread) when I do. 

 

 

 

Edited by Stephen Chambers
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Thanks for all the responses.  Don, the flatness I'm talking about is on the underside of the reed frame whereas the embossing (if one were to do it) would be on the top of the frame, next to the reed.  I don't think there's any issue of out of level on the top surface

 

And thanks for you response Dana. I can see how the reed clamp screws would cause the frame to bend across the rwidth of the frame but I'm struggling to see how they would cause the frame to bend along its long dimension. I can visualise that if the slot was punched out, then reamed to create the vent angle, the forces which cause the metal to flow could easily bend the frame (in all sorts of directions!).

 

Still, it's interesting that at least some of the higher quality makers flatten the underside - although from my trials so far, it hasn't fixed the sensation of redundant air rushing through the reed/frame/chamber.  I think the reeds fit reasonably well so maybe there's something else happening in my particualr example - it only seems to happen on one or two reeds

 

Alex West

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On 5/5/2020 at 3:51 AM, Stephen Chambers said:

 

 

 

 

 

 

 

 

I've been repairing, and tuning, concertinas for 50 years this year, and I can see no benefit in using such techniques in concertinas with English-style construction, which have tapered reed tongues that are easily removed from their frames for adjustment or replacement - so that you can make the tapered reed wider in its tapered slot by cutting a small amount off the tip, and sliding the reed forwards. But I will ask Rick what he thinks about using embossing on them, and report back on that (in a fresh thread) when I do. 

 

Quote

 

 

 

Stephen  , 

your  comment  regarding  concertina reeds having tapered  tongues  got me thinking.  As I had  a  reason to  open my  1927 Aeola today  I  measured  the  tapers. Yes    shallow  tapered  reeds  alright  but,  I  recall that  one of the  reasons   I  came up with  as to why  the sound  of  my other Wheatstone  (1898   flat reed pan  prototype Model 22)  could be  so  different  was  that  the reeds  have parallel  tongues....so  I opened that one too  and  yes  the tongues are parallel.  Exactly  what  difference  this  has  on the  tone  quality  I  could  not  quantify in words  but I'd  be interested in  anyone's  thoughts.

Edited by Geoff Wooff
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12 minutes ago, Geoff Wooff said:

Stephen  , 

your  comment  regarding  concertina reeds having tapered  tongues  got me thinking.  As I had  a  reason to  open my  1927 Aeola today  I  measured  the  tapers. Yes    shallow  tapered  reeds  alright  but,  I  recall that  one of the  reasons   I  came up with  as to why  the sound  of  my other Wheatstone  (1898   flat reed pan  prototype Model 22)  could be  so  different  was  that  the reeds  have parallel  tongues....so  I opened that one too  and  yes  the tongues are parallel.  Exactly  what  difference  this  has  on the  tone  quality  I  could  not  quantify in words  but I'd  be interested in  anyone's  thoughts.

 

I think that deserves a whole new thread of its own Geoff.

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