<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html>   Alan wrote: <blockquote TYPE=CITE>Don wrote: "...if you pitch correct a piano ... and then tune it ... you may find that you wish you had waited to do the fine tuning. Piano frames shift. Sometimes this shift is very dramatic at the bass break or other areas." I may be wrong (always a distinct possibility) but didn't Dr. Sanderson and others test this whole business and determine that all changes to the piano caused by changing string tensions are immediate?  </blockquote> I was not aware of such testing, and would like to read some about it. But I seem to remember a disscussion about this frame shifting thread last year, where some claimed that plate stresses played a very important role in both how the piano reacts to pitch changes, and why the piano changes pitch over time. I will have to re-read some of that to remind myself of who said what.... but there were some pretty strong conclusions made. <blockquote TYPE=CITE>  I'd have to go back and look, but I'm pretty certain that Randy Potter has cited this information and stated, in effect, that the time-honored belief that pianos needed to "settle" following a pitch correction was not correct.  </blockquote> Well... I dont know, but I do know that time and time again have experienced that a major pitch raise (100 ? cents) ends up being more stable if I waited a few days to fine tune it as opposed to doing the whole job in one day. Admittedly tho... I have done no formal study to confirm these results. So of course... any formal study that has been done on the subject would be interesting reading. <blockquote TYPE=CITE>Alan Barnard Salem, MO <a href="https://www.moypiano.com/resources/#archives"></a> </blockquote> As to some of the discussion surrounding rendering across the bridge. Don may correct but I think his "pitch raise"  entailed something in excess of minor pitch adjustments. But as long as we are on about that, I wonder if its not easier to check out rendering problems across the bridge then one might be tempted to believe. Aafter tuning a note pluck the backlength to either measure the frequency or just get its pitch in your ear and then stretch the backlength with a string stretching tool to force tension to decrease on the backlength and increase on the singing length. Then hit the key with a few hard blows to see how much it takes to get the backlength back to its origional tension. If it returns then you have little problems with rendering. If it does not.. then try just retuning the whole string again by quickly lowering tension a bit and then drawing it back up. Recheck the backlength frequency with what you started out with.  My  personal experience tells me that bridge rendering is in general not a huge problem for tuning stability. Sometimes for sure... but by and large it doesnt look that way. Same thing for rendering in general. It can be a pain in the pattoootey for sure... but I dont see a lot of pianos that dont stay tuned because of rendering problems getting the best of me. JMV Cheers RicB   -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway <A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A> <A HREF="http://www.hf.uib.no/grieg/personer/cv_RB.html">http://www.hf.uib.no/grieg/personer/cv_RB.html</A>  </html>