> From: John Ross <jrpiano at win.eastlink.ca> > Date: March 11, 2010 5:06:30 PM EST > It is from Schaff, item number 527A, upright jack spring. > The physical properties are equal taper from top and bottom, to a compacting of a couple of coils, in the centre, like each end. > The old springs were a double at each end, and the winding went wider in the middle. Hi John, I have not installed these springs. However, I have had the experience of uninstalling them and replacing them with traditional springs. The situation is a little unusual, so please keep that in mind while making judgements about its validity to your situation. I was called in after an unsatisfactory action rebuild by another technician. The piano was (I believe) a Chickering console. Someone had installed these springs (which are for a full sized upright action, not a console), and the performance was terrible. Unlike a typical jack spring, these tend to bend in the middle and want to fold into a ">" shape when compressed. In this case, since they were clearly oversized, as they bent to one side or another they would rub against anything else nearby, such as the jack flange, the backcheck wire or bridle wire. This caused not only noise, but friction as well, and the owner was not able to play with any control at mp or softer. Now, please do keep in mind that these were installed in the wrong type of action (a console), and do consider the fact that they might perform far better in their intended role. However, in taking them out and playing with them, their propensity to fold into a ">" shape was clearly evident even when less compressed, as they would be when properly installed in a full sized upright. This was especially true when my fingertips (simulating the wippen body and the underside of the jack tender) were not parallel, which certainly happens as the jack rotates through its motion cycle. Traditional jack springs may slightly bulge in use (i.e. - deviate from a straight line), but their bulge usually takes the form of a gentle arc segment that will not touch any other action parts. After playing with them a while, I decided to avoid these springs, and have ordered traditional Pianotek springs instead since. Because this situation was unusual, I am not necessarily recommending that you also avoid them. I am just sharing my experience and observations. Joe DeFazio Pittsburgh -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100311/43312bd9/attachment.htm>
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