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dj-Sandwich-Ham
Guest
Yesterday, I opened the bass end of a recently acquired Cooperativa LArmonica PA (Im guessing 1950s or so) to fiddle with the reed leathers. One end of the reed banks was held in place with an L-bracket held to the wood by two threaded standoffs. Anyway, the standoffs were fairly corroded and the machine screws were corroded to the point of crumbling.
https://preview.ibb.co/bsNubL/IMG-20181017-163056385.jpg[/img][/url]
Its all non-ferrous metal and going off of fastenals chart of which metals corrode what (and some limited experience in working metal) Im guessing that the L-bracket is Nickel/Monel and the fasteners, with the exception of the washers, were Aluminum. Everything else in the bass end is nice, barely-oiled steel, brass and aluminum.
https://www.fastenal.com/content/feds/pdf/Article - Corrosion.pdf
My question: is there some reason to why they chose to build it this way, or was it just a cost-cutting measure on a replaceable part that did in fact last a good 60 years before failing? Were these industry standard parts, or were they machined specific to each manufacturer/model? (I come from a guitar background where people are extremely superstitious about the material of each and every part, mostly to no good end. Sorry if this is the most inconsequential thing youve ever read)
P.S.
Luckily, the crumbling nickle was quite easy to drill out without any damage to the wood, but it was pretty sickening the first time I heard it crack. All this hardware is getting replaced with stainless (due to supply issues), which is not ideal with the nickel but should last a good long time. By my understanding, this combo would tend to corrode the L-bracket going forward, but that would be far easier for me to recreate in any desired metal than to deal with sourcing the rest in some mystery nickel alloy.
https://preview.ibb.co/bsNubL/IMG-20181017-163056385.jpg[/img][/url]
Its all non-ferrous metal and going off of fastenals chart of which metals corrode what (and some limited experience in working metal) Im guessing that the L-bracket is Nickel/Monel and the fasteners, with the exception of the washers, were Aluminum. Everything else in the bass end is nice, barely-oiled steel, brass and aluminum.
https://www.fastenal.com/content/feds/pdf/Article - Corrosion.pdf
My question: is there some reason to why they chose to build it this way, or was it just a cost-cutting measure on a replaceable part that did in fact last a good 60 years before failing? Were these industry standard parts, or were they machined specific to each manufacturer/model? (I come from a guitar background where people are extremely superstitious about the material of each and every part, mostly to no good end. Sorry if this is the most inconsequential thing youve ever read)
P.S.
Luckily, the crumbling nickle was quite easy to drill out without any damage to the wood, but it was pretty sickening the first time I heard it crack. All this hardware is getting replaced with stainless (due to supply issues), which is not ideal with the nickel but should last a good long time. By my understanding, this combo would tend to corrode the L-bracket going forward, but that would be far easier for me to recreate in any desired metal than to deal with sourcing the rest in some mystery nickel alloy.
