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Jody Kruskal

Why are the holes extended?

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Posted (edited)

569947944_IMG_2618(1).jpg.d6b61266ace3f63ab521b5271d1b9e4c.jpg

 

I'm sure there was a recent thread about this, but I can't remember the conclusion. Here is the internal photo of a Jefferies. Notice the holes have been camfored/extended.

 

Why?

 

Was it to make room for mechanical action or to effect tone or pitch? Or all three?

 

I'm just a player, but still curious about the mysteries of concertina construction.

 

 

 

Edited by Jody Kruskal

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My guess is it has to be something to do with modifying the tone or response, but I don't know what exactly the effect would be or how you choose which chambers to do it on. I would be surprised if the one next to the '8' that is beveled away from the reed tip had a significant effect. Have any other makers done this or was it only Jeffries?

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If it were to make room for for the mechanical action, then the chamfering would all point towards the middle of the hexagon.  In one example it points away.

 

Pitch is defined by how fast the reed oscillates.

 

Tone is affected by a number of factors, but I cannot see how this chamfering would affect it.

 

My guess is that it is to smooth and the air flow into the hole, possibly to aid with starting the reed to move when the button is pressed. Some reeds are harder to start than others.

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Anyone familiar with tuning older motorcycle engines, particularly two-strokes, will have come across 'porting', smoothing/speeding air flow on the way in ( and out ) of the combustion chamber.  The chamfer on the pan appeared to me - not knowing much about concertinas ,to be an effort in the particular 'world' of Jeffries ideas, with their specific reeds, valve shape and pad 'saddles', to be yet another innovation in seeking 'marginal gains' in performance.  

 

 

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2 hours ago, Mikefule said:

My guess is that it is to smooth and the air flow into the hole, possibly to aid with starting the reed to move when the button is pressed. Some reeds are harder to start than others.

 

IF that were the case, might this be done specifically on lower-pitched reeds, which have a reputation of being slow to start?

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38 minutes ago, JimLucas said:

 

IF that were the case, might this be done specifically on lower-pitched reeds, which have a reputation of being slow to start?

 

I would have thought so.  However, I am only speculating.

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If the "R" indicates the Right Hand Side, it would seem doubly unusual to be chamfering these holes, as the notes would generally be in the 2nd octave or upper register.

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This is the left hand....I think there could be some logic in suggesting it is - in part, to assist the low note starting by 'porting' the inlet to speed up and flow the air.  Trying to mirror the image in my hand/head I think those chamfers on the right hand side are (among) the lowest reeds on that side.  A similar case applies on the 'left'.

 

IMG_2368 (1).jpg

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It is in A / E, ( not Ab/Eb ) A=444hz, Society of the Art's tuning.

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post-6143-0-42878100-1361736394_thumb.jpg

My CG has it on both the left (6 holes in addition to the thumb button) and right side (3 holes), and some are undercut towards the centre of the pan - others towards the rim.

 

The original discussion where this came up was about the nasal sounding inboard reeds on Jeffries anglos  (link is here)

 

At the time, I'd seen a lot of examples of this that had the (presumably repair) stamp of "R. Whitten" on the pad board, and speculated that it might have been an after-market modification. Subsequently though, I found other examples without the stamp. Nevertheless, it would be interesting to know if any other maker's concertinas have this sort of mod - I'm thinking particularly of those by Crabb and Shakespeare? If it's only found on Jeffries concertinas, it must indicate it was an in-house practice.

 

Adrian

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Posted (edited)

I was wondering about those chamfers. My earlier, bone button Jeffries does not have them. I wonder at what point they started adding them and what the goal was. 

U6mP0eL.jpg

 

Edited by Pgidley

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Posted (edited)

Wait a minute, could the cut-aways be merely to align the holes better to the chambers?

 

My thought is, to squeeze in everything on 38+ button instruments, the holes, buttons pads and levers have an ideal spacing which does not quite match the ideal reed and chamber spacing, more easily achieved on 30- button instruments. The hole extentions could be just to make these two systems achieve a better fit by slanting the holes to better match thier corresponding chambers.

 

Just conjecture on my part, but it could make sense of this conundrumn. Your thoughts?

 

Testing my hypothisis would not be too hard using rubbings and/or photos of the internal workings of the instruments and laying them on top of each other with photoshop or some such app to see how they align.

Edited by Jody Kruskal

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2 hours ago, Jody Kruskal said:

Wait a minute, could the cut-aways be merely to align the holes better to the chambers?

My thought is, to squeeze in everything on 38+ button instruments, the holes, buttons pads and levers have an ideal spacing which does not quite match the ideal reed and chamber spacing, more easily achieved on 30- button instruments. The hole extentions could be just to make these two systems achieve a better fit by slanting the holes to better match thier corresponding chambers.

 

I think that may occasionally be true with inner chambers where it can be difficult to place the pad directly over the chamber, particularly on the left hand, but I don't think that is the answer in the case of yours and @Sprunghub's photos above. The bevels are roughly parallel to the chambers.

 

It still seems curious to me that some of the bevels face towards the reed tips and some away from them. @adrian brown's photo shows the same thing. I wonder if whoever came up with the idea sacrificed a pad board or two by experimenting with different bevels on each chamber until they got whatever effect they were aiming for.

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Posted (edited)

I had a discussion with Noel Hill a few years ago about the pad hole beveling on Jeffries instruments.  If memory serves his take was this was primarily a post manufacture modification inspired by treatments done to instruments in the flute community.  I remember Noel shaking his head and believing this treatment was unfortunate and unwarranted in most cases as applied to concertinas.

 

It would be interesting to get Geoff Crabb's take.  He is our strongest existing link to the Crabb/Jeffries tradition.

 

Greg

Edited by Greg Jowaisas
to add: "as applied to concertinas."

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This kind of undercutting on woodwind instruments is part of the process of tuning the instrument while retaining a comfortable finger spacing.  I can't see that there would be any direct comparison with concertinas.

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In support of the idea that it is a form of rudimentary porting and helping air-flow to the larger reed chambers, is it the case that Jeffries action boards - by the standards of the time - are thicker than some ( most ) Makers and may have benefited from this small modification.  From my very limited experience inside Concertina's it seems to me they may have used a heavier grade of material.

 

 

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