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#1 David Hornett

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Posted 05 April 2014 - 05:36 PM

Hi,

 

Could anyone direct me to an article which gives precise details of what reed tongue profiling is. I have the silicon spring steel cut to the correct width for the shoes, have tuned possibly thousands of reeds over my time, but never fathomed what profiling is, or rather how to determine the correct profile for a reed. The reeds I have tuned have never been affected in their quality of sound, but then tuning is over such a small range that it most possibly does not affect the profile, whatever that is.. Some nice accurate diagrams would certainly help.

 

 

David



#2 Greg Jowaisas

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Posted 05 April 2014 - 08:16 PM

David,

I would think that it is appropriate to "stand on the shoulders of giants" and take the lead from your favorite manufacturer who has already put in the time and effort (R&D if you please) to find some good solutions and compromises regarding scale, response and tone.

 

So I would find a good example of a Wheatstone, Lachenal, Jeffries etc whose tone and response are preferred and which has reeds that appear to retain their original profiles.

Also check the scale (varying lengths) of the reed assemblies to make sure they are compatible with your project.  You would then use a micrometer to take measurements of the tongue out of the reed shoe in at least 5 places and more, if patience and persistence exist.  This will give you the profile of a reed tongue for that particular note.  Often notes a half step above and a half step below have the same basic profile prior to tuning.

 

If you haven't viewed the Pathe film, "Concertina Factory", which has snippets of the Wheatstone plant, you might find it beneficial.  In the Wheatstone factory, and I would guess many other concertina operations, a plate of spring steel was give a particular profile using a surface grinding machine.  They are usually water cooled which preserves the steel's temper.  The profiled plate was then sheered into strips which eventually become the reed tongues.

 

I believe a number of the modern manufacturers of concertina reeds began with this process of imitation and then develop their own variations according to their likes and needs.  It is a time consuming process and can make one appreciate all the work that goes into making a good sounding concertina.

 

Greg



#3 Terry McGee

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Posted 05 April 2014 - 10:25 PM

http://www.britishpa...rt-in-a-factory

 

Note also the "view as stills" option.

 

 
The tuning chappie seems to be comparing an A and E.  Interesting that it's A at about 432Hz.  Could be the camera was running 2% fast.
 
Or perhaps this conversation had just taken place?
 
"Um, sorry, M. Pathé, we'd love to demonstrate the tuning operation, but we don't have any tuned reeds at the moment."
 
"Let me assure you sir, the Great British Public, as well as being lousy lovers, as we will casually assert elsewhere in this commentary, also have cloth ears.  Anything will do!"

 

Terry


Edited by Terry McGee, 06 April 2014 - 12:44 AM.


#4 Chris Ghent

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Posted 06 April 2014 - 12:45 AM

Terry,

Standard film frame rate is 24 frames, whereas in the English derived TV systems the frame rate is 25. US rate is 30. Note these are half the hertz rate in those countries.

It was usual in UK derived systems to just ignore the 24/25 disparity and play 24 fps film on TV at 25 frames, speeding everything up by 4%. In US systems the disparity 24/30 was to much to ignore and telecine machines worked in such a manner as to duplicate occasional frames (actually half frames, but too much detail if we go down there) in order to keep the time right. This lead to unusual effects sometimes, most notably in sideways panning shots which could appear to jump erratically.

I am not sure what happens these days with transfers to file formats for digital, but would expect the old newsreel footage to have been put to video at 25fps.

#5 Chris Ghent

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Posted 06 April 2014 - 12:55 AM

Hi,
 
Could anyone direct me to an article which gives precise details of what reed tongue profiling is. I have the silicon spring steel cut to the correct width for the shoes, have tuned possibly thousands of reeds over my time, but never fathomed what profiling is, or rather how to determine the correct profile for a reed. The reeds I have tuned have never been affected in their quality of sound, but then tuning is over such a small range that it most possibly does not affect the profile, whatever that is.. Some nice accurate diagrams would certainly help.
David

t

My apologies for taking your thread off track with TV technicalities. You have had a very generous post from Greg J, good advice.
May I suggest a call to Chris Vonderborch who is only an hour or so from you on the Tasman Peninsula. He has made half a dozen decent concertinas and could save you a lot of time.

#6 Terry McGee

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Posted 06 April 2014 - 02:16 AM

Terry,

Standard film frame rate is 24 frames, whereas in the English derived TV systems the frame rate is 25. US rate is 30. Note these are half the hertz rate in those countries.

It was usual in UK derived systems to just ignore the 24/25 disparity and play 24 fps film on TV at 25 frames, speeding everything up by 4%. In US systems the disparity 24/30 was to much to ignore and telecine machines worked in such a manner as to duplicate occasional frames (actually half frames, but too much detail if we go down there) in order to keep the time right. This lead to unusual effects sometimes, most notably in sideways panning shots which could appear to jump erratically.

I am not sure what happens these days with transfers to file formats for digital, but would expect the old newsreel footage to have been put to video at 25fps.

 

Yeah, I tried to think of rational reasons for the disparity (I know - rational - so last year!), but couldn't think of something that would give a 2% change.  A 25:24 ratio (about 4%) would make A440 into A422, or A458 if applied the other way.  By 1961 they should have given up on wind-up cameras which had been my other thought.  Perhaps it's just accumulated error from a number of causes?

 

You can sometimes pick up clues by analysing the gaps in commentary for hum artifacts.  A quick look located some 102Hz, which is 2% away from the second harmonic of 50Hz.  But I also found some 59Hz!  It probably doesn't warrant a full-scale judicial enquiry!

 

Terry



#7 David Hornett

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Posted 06 April 2014 - 02:41 AM

Thank you. I have been doing some measuring before I made the post, and there was absolutely no rhyme nor reason to the profiles, I thought I may have been able to come up with a nice little chart, but no, then figured that a quick post may give some insight: which it did, thank you Greg -- I'm off with my micrometer to measure a lot of reeds, and then a quick trip to Chris, we have met around the traps over the years.. An untuned lachenal I have (ie has absolutely no evidence of ever having been tuned and is in the old pitch) has the following profile beginning at the reed screw end (in mm):

 

Low D# .40, bottom  .28 (middle) .73 top end 

Low E 36, 33, 46

A# below middle C .37, .25 .48

Middle C .37, .25, .35

E above C .23 .22 .32

A high C .20, .18, .15

 

I have measured a few others too. I have a very nice Jeffries, but my hands shake with the thought of taking its reed tongues out to get fine measurements.

 

 

Thank you all again.

 

David



#8 Terry McGee

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Posted 06 April 2014 - 03:18 AM

To make it easier to visualise....

 

Lachenal reed profile.GIF

 

I wonder if two more measurement points (at the quarter way marks) might enlighten us further?

 

Terry


Edited by Terry McGee, 06 April 2014 - 03:24 AM.


#9 David Hornett

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Posted 06 April 2014 - 06:35 AM

Thank you for the graph, I have gone back and here are a few more , accurate this time, measurements (Red below are the additional measurements including any more accurate measurements. (Measurements are read from the attachment end, ie, from immediately on the free side from where the tongue passes under the screw plate) None of the low notes have solder weighted ends.The instrument is a Lachenal Duet 8816 (Tapered reeds. I assume tapered reeds would need thicker ends, unlike the straight broad reeded Jones. I have a nice "Broad reed' Jones and will have a go at measuring it too.):

 

Low D 40  31  30  45  82

 

Low D#  40  31  28  49  73 

Low E  36  27  33  41  46

 

A# below middle C 37  24  25  43  48

Middle C  28  25  25  34  35

D above middle C  36  25  23  33  41

E above C  23  21 22  29  32

A high C .20, 19 16 15 15



#10 Chris Ghent

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Posted 06 April 2014 - 06:57 AM

Three is an inadequate number, and five not really enough. Take the tip measurement for example, it tells you nothing of the makers intention, just the result of tuning attempts over the past 100 years. And the important information about a low reed is missing. Where is the thin point, how wide is it, how thick is it? To get a decent measurement you need one per mm all along the reed.

 

Taking the tongues out to measure them would be a very long job with little chance of getting them back in perfectly without good equipment. Instead get an old micrometer, disassemble it and turn down the hammer to 1mm for the last 3mm. Reassemble and adjust and now the thin part can fit up to the reed from behind in the slot while the anvil sits on the top. Another method is to set up a dial gauge vertical over a brad which is sticking out of the base by 2.5mm. Zero the dial gauge on the brad and thenm gently lift the gauge arm and lay the reed assembly so the tongue is sitting on the brad. Lower the gauge arm again and as you slide the reed along the brad the gauge will read off the thicknesses. You need to check calibration often.Tape a paper ruler along the reed for reference. Having a scribe to help is nice, you can call off the values.

 

Copying Jeffries reeds is all uphill due to the small number of reed frame sizes and the bass reeds are typically not sufficiently pitch stable for a modern concertina, I suggest finding a good Wheatstone to copy. Chris will have one.



#11 Terry McGee

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Posted 06 April 2014 - 07:21 AM

Heh heh, the old rule when taking data is to keep taking data until you stop learning anything new.  In the meantime, here's where you're up to, a definite improvement on V1.0.

 

Lachenal Duet 8816 Reed Profile.GIF

 

(Remember it's just a thumbnail, click on it to see full size)

 

If you wanted to test the benefit of taking more data points, with a view to determining how many data points you really need, just pick one or two reeds (say one big, one little) and do the 1/8th points.  I'm happy to whack them on the graph.  

 

It would be nice to add the thickness of the metal under the clamp, but I can understand why you mightn't want to undo those two little screws.  Can you use a feeler gauge at the side of the clamp to gauge the thickness?

 

Terry


Edited by Terry McGee, 06 April 2014 - 07:52 AM.


#12 Wolf Molkentin

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Posted 06 April 2014 - 08:12 AM

It would be nice to add the thickness of the metal under the clamp, but I can understand why you mightn't want to undo those two little screws.


That made my day, or at least noon time, Terry!

And as to considering frequent tuning, David had described the instrument as untuned, without any marks on the reeds which are in old pitch.

Interesting thread!
Best wishes - Wolf

#13 Geoffrey Crabb

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Posted 06 April 2014 - 11:49 AM

 Another method is to set up a dial gauge vertical over a brad which is sticking out of the base by 2.5mm. Zero the dial gauge on the brad and thenm gently lift the gauge arm and lay the reed assembly so the tongue is sitting on the brad. Lower the gauge arm again and as you slide the reed along the brad the gauge will read off the thicknesses. You need to check calibration often.Tape a paper ruler along the reed for reference. Having a scribe to help is nice, you can call off the values.

 

 

Beat me to it Chris  :mellow:

 

 

I am sure someone took measurements in the past and published the results but I can't remember who? or where?  

 

Geoffrey



#14 David Hornett

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Posted 06 April 2014 - 04:07 PM

Terry,

 

Your little graph has me rather enthused. I did take the reeds out of their shoes for the measurements, I have never had any problem removing and replacing reeds from shoes and getting pretty well exactly the same pitch as before removal on replacement. The secret is to use thin strips of feeler gauge, measure reeds before removal from the tip to the shoe. (That being said, I still don't want to interfere with my jeffries vitals, but i may use Chris' suggestion for that and turn down a micrometer.) The instrument shows absolutely no signs of having been tuned, no scrapings or scratchings over the top of the original scratchings, middle or tip: nothing. I am pretty sure they are virgin reeds. If I am not too stuffed tonight after work I will get back to you then with a few more measurements. I will take a few from the Jones, once I turn down my micrometer, parallel reeds will be an interesting comparison, however it has been tuned.

 

Thanks again everyone



#15 Terry McGee

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Posted 06 April 2014 - 05:13 PM

No worries, David, happy to help, and keen to learn.  

 

In regard to turning down the business end of the micrometer I wasn't so sure.  I imagine the anvils are hardened, and may even be something very hard like tungsten carbide.  They would need to be ground, not turned.  Mine have what appears to be a 2mm slice of TC brazed to the end of the shaft, the whole thing then neatly ground.

 

I guess dropping a ball bearing into the reed shoe slot and measuring that as well is a bit too klutsy?  Or a short cylinder?  Harder to be precise about location I concede.

 

Or go with Chris' second thought, or Geoffrey's suggestions, or modify a luthier's thickness caliper? (Check that the end of the clock is either pointy enough to get down to the narrowest reeds, or can be unscrewed and replaced with a custom tip.)

 

And don't just sit there man, we're all waiting for the next exciting installment!

 

Terry



#16 Terry McGee

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Posted 06 April 2014 - 06:47 PM

Now, while you're fooling around with that heap of reeds from the Duet, tell us what happens to length as you go from the highest pitch reeds to the lowest.  I assume the lengths of the reeds don't vary infinitely, but in tiers?  If so, it would be interesting to explore at least one tier to see how the maker used profiling to make up for the fact that adjacent reeds are of the same length.  

 

An extreme example of this is the guitar, which has 6 strings of almost precisely the same length, but uses gauge differences and overspinning (adding weight without stiffness) to mask that unfortunate starting point.  Another is the tail of the harpsichord.  Along the bent side, the strings are getting longer as they are getting lower.  Comes a time when the Domestic Authority determines enough is enough and the maker cuts the exponentially growing tail off abruptly.  At that point, string thickness and string material become the only levers left to pull.

 

Musical instruments are full of lies, designed to get around the inconvenient laws of physics.  I'm not sure what that makes instrument makers?  Whoops, excuse me, I have to go extinguish my trousers.  (Apologies in advance to non-native English-speakers on that one.)

 

Terry



#17 Chris Ghent

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Posted 06 April 2014 - 08:15 PM

The micrometer I turned down was very soft in the hammer. I also ground away a section of the anvil to allow it to sit closer to the clamp. My first reading would be at roughly 2mm. There is most often enough material protruding behind to clamp to measure the base stock size. If the micrometer was digital you could just glue a tip onto the hammer and re-zero.

Wolf, even in a an original hand profiled reed with no retuning you will not necessarily get the maker's intention, especially on a Jeffries with so many pitches to the reed size. After profiling the reed is fitted to the frame which will change its pitch. It is then put in a instrument which will change it again. It is very common in a lower reed below the point at which there is a belly in the profile to find the tip, rather than becoming a bar (ie. being parallel in thickness) of say .5mm for the last 7mm will suddenly dip down towards say .4 over the last 3mm. If just taking a tip reading you would be mislead into thinking the whole bar was .4.

Beat me to it Chris  :mellow:
attachicon.gifReed - Measuring tongue thickness.doc
 
Geoffrey

I thought I might have invented that but the likelihood is you told me about it..! I'd wish for a better memory but imagine all the things you wouldn't want to remember...

#18 Chris Ghent

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Posted 06 April 2014 - 08:23 PM

Terry,
 
Your little graph has me rather enthused. I did take the reeds out of their shoes for the measurements, I have never had any problem removing and replacing reeds from shoes and getting pretty well exactly the same pitch as before removal on replacement. The secret is to use thin strips of feeler gauge, measure reeds before removal from the tip to the shoe. (That being said, I still don't want to interfere with my jeffries vitals, but i may use Chris' suggestion for that and turn down a micrometer.) The instrument shows absolutely no signs of having been tuned, no scrapings or scratchings over the top of the original scratchings, middle or tip: nothing. I am pretty sure they are virgin reeds. If I am not too stuffed tonight after work I will get back to you then with a few more measurements. I will take a few from the Jones, once I turn down my micrometer, parallel reeds will be an interesting comparison, however it has been tuned.

Thanks again everyone


The advantage of method two is you can have a hand free for notation. Putting the dial gauge in the quill of a drill press makes it much steadier than a magnetic clamp and removes much of the continual recalibration to zero.

If you continue removing reeds from the frames one method used in the past to orientate them was to place thin thread around the reed and gently push down and the thread will spread the load. The thread needs to be just thicker than the gap. Richard Evans showed me reeds once which still had thread around them after 100 years. I think the intention was they would be cut off!




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