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Designing A Modern "campaign Concertina" For Travel And Tropic

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#55 alex_holden

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Posted 15 October 2015 - 04:07 AM

I have made ends from Titanium, it was not particularly difficult to machine. It is not forgiving; unlike brass or nickel silver you cannot ignore feed and speed recommendations and still get a good result.


Interesting, how did it turn out and would you use it again? Did you need to apply any kind of surface finish?

#56 Chris Ghent

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Posted 15 October 2015 - 07:22 AM

It was Grade 2, .6mm, which I found at a jewellery supplies shop. The method I use for machining metal ends is to employ an engraving cutter, 60°, and corner sharpening, which leaves the internal corners sharp looking. From memory I used about 4 passes to get through the .6mm. This leaves a beveled edge which when polished with a mop looks neat. While it was easy enough and looked very good I would only do it again if I felt an overwhelming need to be light. I prefer the warm colours of Nickel Silver.

There is little chance it will catch fire while doing ends but I did buy a fire extinguisher after a pile of fine swarf ignited under the lathe while making buttons.

#57 Bullethead

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Posted 15 October 2015 - 08:45 AM

There are some amazing craftsmen here who make beautiful things out of fancy materials.  I marvel at their talents because I utterly lack them myself.  So here's how I would make my own "campaign" concertina.  I would actually make all my concertinas this way, and their being suitable for campaigning would just be a byproduct of my lack of proper tools and talent to make anything fancier.

 

First off, I would make the ends entirely from polyurethane.  Rather than machine it (which is possible but a bit tricky and requires tools I don't have) I would build the ends up out of sawn sheets same as with wood, held together with a suitable adhesive.  Other than sawing strips to dimension, the only other machine operations would be drilling the button and sound holes.  Rather than get fancy with F-holes and scrollwork, I'd just drill a bunch of round holes so the ends would look like Swiss cheese.  So that's the face pieces and reed pans.  I"d make the buttons by sawing polyurethane rod stock to length.  For the bellows, I'd use flex duct of diameter appropriate to the ends, probably held on by hose clamps.

 

For the actual noise-making parts, I'd buy accordion reeds off-the-shelf, leaving just the action to deal with.  The action is a bit more of a challenge.  The pads would obviously be polyethylene or polyurethane foam to avoid rot.  To rust-proof the action itself (and to avoid all the fiddly work of cutting and bending levers and springs, then mounting them), I'd  try hard to devise some pneumatic valve actuation system so the whole system could be made off-the-shelf tubing and fittings.

 

The pneumatic valve system (I'm typing this as I.m thinking it up) would function similarly to air brakes on a truck.  You'd have an air reservoir kept at higher-than-ambient pressure by the normal motion of the bellows during playing.  This pressure would keep the valves seated when the buttons were not pressed.  Pressing a button would vent air on 1 side of the valve to ambient, causing the higher pressure on the remaining side to push the valve open as long as you had the button depressed.  When you release the button, the system returns to equilibrium with high pressure on both sides and the valve closes.  Would need a spring to help with this, but that would be a simple, off-the-shelf thing instead of hand-made.  Also, before playing, you'd have to give the concertina several pumps to charge up the valve system reservoir :).

 

Note that by typing the above, I just destroyed the patentability of pneumatic concertina valve systems.  It's a public domain thing now, so feel free to use it :).



#58 Dana Johnson

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Posted 15 October 2015 - 01:24 PM

I used stuff called Dymond Wood by the Rutland plywood Corp in Vermont for all the wood parts of my first couple concertinas. It is essentially waterproof. And completely stable. They take 1/16" plies of birch, dye them, impregnate them with phenolic resin, then lay them up parallel grain, not cross, and squash the lot in a heated press to 1/2 the original thickness. Very hard, about like ebony in density. To finish it, all you need to do is 220 grit sand and polish on a muslin buff with some good cut and color compound like fabulustre. It also taps very well. I fastened all the reeds with little 2-56 button head cap screws. No need for nuts. I don't use it for my concertina innards anymore, but still make my end frames and hand rests from it. It is also very pretty stuff. ( see website for pics ). The concertinas I did make using it inside and out sounded quite good and were plenty loud enough. I played one for years before I could afford one of my newer ones. It is still going strong 20 years later in the hands of a student. You can get it in various thicknesses, but I used 1/8" for the reed pan and action pan with 1/16" for the chamber walls. Mind you this had concertina reeds in it. You'd need 1/8" rails to mount reed plates on and normal hybrid construction with the rails glued to the back of the action pan, rather than a separate reed pan. I used rubber toughened CA to glue the rails and frame corners w /corner blocks. It has held up fine. I used normal bellows consruction for those, but no reason you couldn't marry it to something artificial. Though I think they are terrible, you can do an origami folded bellows where the peaks line up with the valley of the adjacent sides. No gussets needed, all straight lines. Can be formed from a tube ( with an appropriate form underneath to help create the golds evenly. Stagi has used them. Which is probably why they were terrible. Idea is sound.
Dana

#59 Dana Johnson

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Posted 15 October 2015 - 01:33 PM

So it sounds like with anodising on the aluminium, lacquer on the CF, and some sort of plastic or rubber gasket between the two, we may still be OK. The instrument only has to cope with humidity and an occasional rain shower, not total submersion in seawater. We were planning to use titanium end screws anyway, plus they could be sleeved with a tube of something non-conductive like acetal where they pass through the soundboard (the nuts will be embedded in the acrylic bellows frames). I think using titanium for the end plates would probably be overkill!This message brought to you with the assistance of a very purry cat head-butting my hands and drooling on the keyboard. :rolleyes:


Why not nylon bolts?

#60 JimMacArthur

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Posted 15 October 2015 - 02:37 PM

FWIW, Rutland Plywood Corp suffered a catastrophic fire last year.  No human casualties, but the factory is down for the count.  They may have licensed the brand, but I haven't found an alternative source yet.  I'm definitely interested in resin-impregnated wood products, so please post if you find something good.



#61 Dana Johnson

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Posted 16 October 2015 - 05:57 AM

Just noticed that myself! I was getting ready to reorder too!
Not good. A lot of people used their products.
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#62 MatthewVanitas

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Posted 16 October 2015 - 05:57 AM


FWIW, Rutland Plywood Corp suffered a catastrophic fire last year.  No human casualties, but the factory is down for the count.  They may have licensed the brand, but I haven't found an alternative source yet.  I'm definitely interested in resin-impregnated wood products, so please post if you find something good.

 

Yikes, frightening stuff! I've seen Dymond Wood used for Irish flutes and whistles before, pretty stuff.

 

I used normal bellows consruction for those, but no reason you couldn't marry it to something artificial. Though I think they are terrible, you can do an origami folded bellows where the peaks line up with the valley of the adjacent sides. No gussets needed, all straight lines. Can be formed from a tube ( with an appropriate form underneath to help create the golds evenly. Stagi has used them. Which is probably why they were terrible. Idea is sound.

 

Dana, do you have any images which help explain this idea?



#63 alex_holden

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Posted 17 October 2015 - 02:10 AM

I used stuff called Dymond Wood by the Rutland plywood Corp in Vermont


Thanks for the suggestion Dana; unfortunately I don't know of a UK supplier of Dymondwood other than tiny pieces for pen turning and knife scales. I did a bit of research into resin impregnation of wood - apparently it's possible to DIY but it requires a vacuum chamber and possibly a curing oven. I think for this project though I'd rather stick to materials I can get hold of easily.

Nylon screws: like your out of the box thinking, but I'm not a fan of them, particularly in smaller sizes, because in my experience they strip easily and the heads get chewed up if you so much as look at them funny.

Any thoughts on the use of stainless spring steel for the reed tongues? I understand there is a harmonica manufacturer who uses it, and players seem to like it apart from it being much more difficult than brass to retune. Phosphor bronze may be another possibility if I can find the right kind as shim stock...

#64 Graham Collicutt

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Posted 17 October 2015 - 07:35 AM

I 'll post this again: http://www.accordina....php?lg=1&rbq=3     Accordina, stainless steel reeds and construction, they may have some advice.



#65 alex_holden

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Posted 17 October 2015 - 08:14 AM

Sorry, yes, it does appear that they are using stainless for the reeds as well as the casing.

#66 MatthewVanitas

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Posted 18 October 2015 - 05:33 AM

I'm certainly fine with either titanium or aluminum, both of which as I understand it become even more durable with anodizing. I suppose the sheer number of 150+ year-old concertinas that have delicate carved wooden ends which *haven't* broken out is an indication that it's a workable method, but there's something that always makes me cringe at those little splinter-able curly bits in wooden fretting, worrying when they will eventually snap off.

 

For reeds, my vague impression is that the old bronze reeds were more prone to going out of tune and/or breaking than steel, but would modern phosphor bronze have that problem? I don't have a great need for volume since this instrument is mostly for playing alone for fun, vocal accompaniment, maybe jamming with a guitarist, so quieter bronze reeds wouldn't be a problem if they still have durability. But if durability is suspect, I'm fine with a steel that's not over-prone to corrosion.


Edited by MatthewVanitas, 18 October 2015 - 05:35 AM.


#67 alex_holden

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Posted 18 October 2015 - 05:59 AM

For reeds, my vague impression is that the old bronze reeds were more prone to going out of tune and/or breaking than steel, but would modern phosphor bronze have that problem? I don't have a great need for volume since this instrument is mostly for playing alone for fun, vocal accompaniment, maybe jamming with a guitarist, so quieter bronze reeds wouldn't be a problem if they still have durability. But if durability is suspect, I'm fine with a steel that's not over-prone to corrosion.


The impression I got from discussions on harmonica forums is that phosphor bronze and stainless steel reeds are both more durable than brass, but opinions differ as to whether PB lasts longer than SS or vice versa. The amount of attention paid to profiling and tuning makes a difference to longevity too (some harmonica tuners go so far as to polish the reeds to eliminate any scratches where a fracture could begin). PB would almost certainly be easier to hand profile and tune than SS because it's a lot softer.

#68 MatthewVanitas

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Posted 20 October 2015 - 06:12 PM

Something to bear in mind for later along in this process, since this piece is mostly for self-enjoyment and is limited in keys, would it make sense to tune it to a "sweetened" temperament rather that Equal Temperament, something like a Quarter-Comma Meantone based around C or G?



#69 inventor

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Posted 21 October 2015 - 12:15 PM

If you wished to limit yourself to only a few keys a bisonoric  concertina could be set up to a "double just" temperament. That is to say the supertonic note of the scale could play on one button in one direction. a comma apart from the pitch of another button played in the other direction. For instance  in the key of "C"  the pull d' on the (c'/d') button and the push d' on the (d'/e') button could be tuned a comma apart, so that both the D minor chord and the G major chords would be perfectly in tune. I have described exactly how this could be done for a 25 button Melodeon in JAN 2013 on "melodeon.net" (under the title "temperaments and things", page 4) for 4 related keys, (A/D/G/C) in that case. But this could be reduced to a shorter compass, and less or different keys if you wanted it to have less buttons.

 

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Edited by inventor, 22 October 2015 - 01:08 PM.


#70 Dana Johnson

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Posted 25 October 2015 - 09:07 PM

Thinking Nylon only for it's insulating properties with the carbon fiber route.
I lucked out and discovered enough Dymond wood hiding in my shop for another 30+ instruments.
I used to seal my reed pans with a acetone vehicle Minwax woid sealer that I think would protect wooden parts from moisture damage. I quit using it a long time ago because it added about 10 gms / reed pan. You need to use well quartered wood with it though because it tends to drive moisture out of the wood which can cause cupping. Being able to use wood opens your options up. My action pan floats in a rabbet so it can shrink or expand in the confines of the end frame without risking splitting.
Stainless reed steel would be preferable to P Bronze. The bronze has better spring qualities than brass and is available in sheet. ( used to punch my reed shoes out of it, and still use it for lever posts.) but it won't stay bright. I haven't used it in damp conditions, but in ordinary humidity, it does oxidize to some degree. it probably isn't worse than most brasses, but not better either.
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#71 alex_holden

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Posted 26 October 2015 - 03:24 AM

Thanks for the advice, Dana. Good news about the Dymond wood!

I guess the problem with tarnishing of brass/bronze reed tongues is that the extra mass of the oxide layer makes them go out of tune?

I was considering using either aluminium bronze or naval brass for the reed shoes, assuming I can source some sheet in the right thickness.





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