At 05:33 PM 3/7/99 -0800, Del wrote: >choose a larger pin or gluesize the hole. I didn't bother with the blunt pins >sold at a frightful cost by S&S. I used standard pins -- they thread easier and >cause less damage to the second bushing as they pass through -- and cut them with With respect to Del, part of the beauty of servicing Teflon actions is you can push the pin part-way out, carefully ream the hole and then push the pin back in. It requires minimum movement of the pin through the wood and places less strain on the bushings as well as allowing for greater accuracy in the pinning. By design the rounded ends of the finished pins cause no damage to the second bushing as they pass through. >a sharp flush cutting side cutter. Contrary to popular belief the residual burr >won't cause any trouble at all. It doesn't cause any trouble with felt bushings >either, but I'm sure it will take more than facts to convince anyone of that. I agree with the burr not affecting cloth bushings if the cut is good. With the above technique cut pins have great potential to damage the freshly-reamed teflon surface when you push them through, eliminating that extremely valuable service technique. As for the expense of finished pins a "set" is about $4. I've never actually seen one wear out although I suppose it's possible, and if the pins are tight in the wood you could re-use them with new bushings unless they're visibly damaged, old or bent. Check them with a Radio Shack pocket microscope if you want to make sure. When you compare the cost and time spent re-bushing a set of hammers with cloth to the $20 for a new set of bushings and pins the Teflon system is much faster and cheaper in the long run. In the time it takes simply to prepare a set for rebushing with cloth every hammer can be repinned with new Teflon bushings and the piano back in service. >long. I could carefully press the cutting end of the reamer all the way through >the first bushing and cut the second bushing using the first as a guide to keep >the hole straight. I would then -- again, very carefully -- pull the reamer out, >turn the fork over and repeat the process cutting the first bushing. I would then >verify the fit and friction of the pin before assembly. Make sure that you have >the same amount of friction in each bushing. With just a bit of practice this >became a one-shot operation. Once you have verified this you can assemble Rather than doing it one-shot and risking damage to the guide bushing, have the reamer sticking out from the broach holder just the thickness of the bushing. Press the pin part way out, carefully press the reamer straight in, turn once and pull it out. If it doesn't feel right, do that again. Then press the pin back in and repeat on the other side. Check your work with a friction gauge making sure the flange travels smoothly and keep the friction as low as possible without totally eliminating it. Excessive friction in these centres is a major problem, IMO. In addition to the loss of power and heavy touch, if I recall my thermodynamics correctly friction translates into heat and I have some concerns about the effect of even slightly heated metal rods running through a precision-reamed Teflon bushing, especially as the assembly is exposed to the effects of gravity as it cools. >center. Check overall friction of the center and trim the pin. Don't worry >about the slight burr. As long as you never want to press the pin out again without replacing the pin and perhaps the bushing. >The resulting bushing was solid, quiet and trouble free. And durable. Yes, Not to mention easy to service once you know how. >The Teflon bushing was and is a much maligned development. In fact, it was Absolutely! >true that they were introduced as a cost cutting measure replacing another >problematic part, the felt bushing. There is nothing inherently wrong with that. I have heard pianists complain that the Teflon introduces an artificial connection to the natural flow of wood, leather and felt. Mind you, I've heard the same complaints about plastic keytops and vinyl bench coverings, so who knows? >Piano manufacturers should be constantly looking for ways to reduce their costs. I would agree in the case of mass production pianos, although I'd prefer that they look for ways to improve their efficiency rather than just "reduce costs". With the high-quality instruments they should be looking at ways to improve their art regardless of the cost. When you're spending that much money on a piano, a few thousand extra for a properly-built soundboard and a balanced action doesn't seem too much to ask. >What got lost somewhere along the line was that just as much care was required to >properly install and fit the Teflon bushing as was needed with the felt bushing. I think the problem was just that they were different and there wasn't enough information about what to do with them. >The Teflon bushing has now gone >into history as a terribly bad idea along with the general use of plastic in piano >actions. Too bad, I remain convinced that the Teflon bushing was really quite a >good idea and handled properly -- and with some further development work -- might >well have freed the industry from the problematic felt bushing. Spoken like a true engineer, Del! B-}) John John Musselwhite, RPT - Calgary, Alberta Canada Registered Piano Technician http://www.musselwhite.com email: john@musselwhite.com
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