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What are metal ends made of?
Chris Ghent replied to Andy Holder's topic in Instrument Construction & Repair
When I last scored German Silver the only source was jewellery supply houses. It was not 5mm! They had .8 and something thicker, maybe 1.6. To add to the list of potential end materials; about 15 years ago I cut out two sets of .7mm titanium ends. One of them is out there somewhere, the other is here somewhere on a shelf. I did it by engraving right through the metal (quite a few passes) with a 60° cutter with corner sharpening software. The titanium was OK to look at, not harsh like chrome or dead like SS. I prefer german silver for its warm yellowish tone and its constantly changing finish. The titanium would probably stay shiny for ever. -
You say the D/E, and suggest both notes are dull. If this is true, look for leaks in the chamber, down between the pan and bellows frame or across the top of a partition, or a leaking pad.
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Reed slot stepped profile
Chris Ghent replied to 4to5to6's topic in Instrument Construction & Repair
I think I’d better make one with a similar offset and compare the sound. -
Why Are Concertinas Hexagonal?
Chris Ghent replied to LeadFingersErnie's topic in General Concertina Discussion
I’m surprised this has not been mentioned as it is an important point. The more sides a concertina has the smaller the square area (when comparing concertinas with similar AF measurements). A smaller square area is important when trying to optimise response. I did the maths a long time ago and don’t have the results to hand but my recollection is a 6” octo is around 8% smaller than a 6” hexagon concertina. As the number of sides gets larger the percentage decrease in sq area with each step diminishes and the amount of work increases and going beyond 8 sides seemed pointless. So a square might offer the most space but it is also the least efficient. When I say optimised response, I mean fast to speak, but also requiring the least effort. -
Pinky/thumb rest screws - where to find?
Chris Ghent replied to fatt_mazio's topic in Instrument Construction & Repair
There was a bloke called Old Nickelodeon (edited to add, I remember, it was Old Nickelby) or something close to that on this forum who had a lot and was handing them out about 5 years ago. Something to consider is the screw itself is unlikely to have lost its thread, and the problem is actually the wood it screws into has been chewed out (though sometimes the screw head has been damaged by the same issues that chewed out the wood, usually a heavy handed user thinking that tightening the screw is the solution to all problems). This means a replacement screw will also not lock up in the wood. The solution is a slightly larger screw, which may look oversize at the head and protrude too much, or repairing the wood. You could try a sliver of wood in the hole before putting the screw in, not terribly elegant but kept many things working in the old days, or drilling the place the screw goes in and turning a wood plug to glue in to the hole. Very important to use a screwdriver that fits the screw perfectly with these tiny heads. -
All concertinas are compromises and the 26 key is just one such. Plenty of good music has been and still gets played on a 26 key.
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Reed slot stepped profile
Chris Ghent replied to 4to5to6's topic in Instrument Construction & Repair
Really good observation and question 4 (for short). A long time ago while playing with a ruler on the edge of a table I realised when the ruler is pinned back from the edge of the table it makes a noise but none when the clamping is at the absolute edge. I also realised when the clamping is back from the edge the up amplitude and frequency must be different from the down amplitude and frequency because the ruler is longer in the up direction. What must this do to a) the tuning, b)the partials (harmonics) and c) the efficiency of the swinging action? I decided to make the clamp edge and the frame slot edge as closely aligned as possible in the interests of efficiency. The inefficiency of having them misaligned comes from the energy in the tongue being absorbed by the frame when the tongue comes from the longer half cycle and hits the edge of the slot. More recently I have been wondering about the effect on harmonics of the combination of a longer half cycle and a shorter half cycle. I know its a small difference but it is a difference. I took apart a couple of Jeffries reeds I have lying around and the mismatch between the edge of the clamp and the end of the slot was large. Inconsequential so disregarded, inattention to detail, or deliberate policy? Don’t know. -
Reed slot stepped profile
Chris Ghent replied to 4to5to6's topic in Instrument Construction & Repair
456, I suspect keeping the better craftsmen together during the war might not have been hard because they would have been older men. They might have had to do war work in the factory though. I’ll send Dana a prod..! -
Reed slot stepped profile
Chris Ghent replied to 4to5to6's topic in Instrument Construction & Repair
PS. I feel like I saw a Dipper concertina a long time ago that had the stepped draught slot. -
Reed slot stepped profile
Chris Ghent replied to 4to5to6's topic in Instrument Construction & Repair
456, sorry for hijacking your thread. As an act of contrition I’ll address your question directly. A long time ago I made a reed assembly using a machined stepped slot because it seemed like an easy way to adjust the draught in a repeatable way (as opposed to freehand filing). My recollection is the reed was a lower one, perhaps a B one tone down from middle C. The resulting reed worked perfectly well except it used more air than a conventional reed and seemed more mellow. I did not continue with that stream of thought. I remember there used to be an accordion manufacturer who trumpeted he was the inventor of the high output piccolo reed. The accompanying picture showed a similar effect, created by using a round cutter and not extending along the reed very far but tiny reeds tend to move more at the tip so I think it could be directly compared with a full recess on a lower reed. It occurred to me the stepped draught could be more efficacious on a higher reed where air use is not much of an issue. Drawing Dana Johnson into this discussion could only help because he is a very practical man with a lot of good science behind him and I know we have discussed this subject at length some time ago. He is very good on draught angles and does them differently to most others. If he doesn’t join in, an email to him would get a good response. -
Reed slot stepped profile
Chris Ghent replied to 4to5to6's topic in Instrument Construction & Repair
LJ, thanks. If you can understand that paper all power and respect to you! I was intrigued by what you said because it runs counter to the generally accepted (not the same as saying right) understanding of harmonics around here, in my experience. This would say the first harmonic should be the octave. I just ran a G3 note through a spectrum analyser and it came out with the fundamental G3 at -6cents, and the first harmonic at G4-2.9 cents. The second harmonic is D5 at 0 cents, the third G5 at 0 cents, the fourth B5 at -15, Etc. It is not until the 8th there is a serious discord, an A6. This conforms with the very general statement, the higher up the harmonics the more discordant with the fundamental, and consequently the drive to increase the volume of the fundamental as it will drown out the discordant higher harmonics. They can also be diminished by wood structure. Please don’t think I’m saying you are wrong, I have no source to back up what I am saying other than finding evidence from a cheap spectrum app that roughly supports it. It could be confirmation bias. I imagine Tom Tonon would have good info on this. -
Reed slot stepped profile
Chris Ghent replied to 4to5to6's topic in Instrument Construction & Repair
Little John, what is your source for this..? -
You could just have said “find a piano accordion…”