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Showing results for tags 'key heights'.
When servicing and repairing concertina, you occasionally come across ideas from previous repairers, some are filed away for future reference, others make one want to wince. To day I have been looking at the action of a George Case baritone. Rare and beautiful until you try to play it. The problem statement was that the keys feel loose and sometimes jam. A quick examination showed a key travel of around 4.8mm, some are worse and the guide peg under the keys were hovering over the mouths of the peg holes. Clearly the keys were set far too high. Other observations show a set of brand-new pads, a total re-bushing of the keys and all new dampers. Also, the instrument has been fully re-sprung. The workmanship is neat and tidy, someone has put a lot of effort into this action, but a lot of it was wasted. The key’s vertical travel expected is usually 3.2mm (1/8 ins), yet there was a consistent ‘error’, not just on a couple of keys but across both sides. Needless to say it was a result of the last service work. The pads fitted were made with very thin felt, with the result of consistently lifting the key heights and thus the guide pegs out of their holes. This could have been OK if the action arms had been bent down to adjust the heights of the keys. Thankfully the repairer did not do that, as the brass arms on a 160yr old instrument can be very brittle and casualties can easily result. In this case the brass is so delicate and soft. I thought I had done damage when making a very minor adjustment, thankfully not. A major mistake the repairer made was to not match pad thickness to key travel and the action’s design height. By selecting appropriate pad thicknesses, you can make life so much easier and reduce risk of lever arm fracture. The next wincing point was the removal of the pads for replacement. The leather beads (AKA spuds) on the end of the arm had been bonded in place on the arm (no real problem with that), but then the pad was glued to the bead with some form of rubber glue. This glue was starting to deteriorate and was stringy and tacky, like blobs of under chewed brown chewing gum. The pads were ‘floating about’ and I had to peel the substance off each arm end fingernail full by fingernail full. I guess I am pleading here for the avoidance of ‘petroleum’ based adhesives, like rubber cement, Evode, Bostick etc, etc. Please use a traditional adhesive or a white PVA. Thankfully I was able to pick the old glue off without bending the levers. The bottom line? Choose the right thickness of pad and then set the key heights remembering the target overall travel of 3.2mm. Then use the appropriate glues. Pads should last 20 yrs plus, as must the glue.