Pianotech

I've been slow in picking up an issue that I now understand has been present for a while.  The Fazioli F278 here at the university has been making a knocking noise when the shift pedal is fully depressed.  As I probed into it, I discovered that the shift mechanism would move the action frame just enough that the trichord hammers would clear the left string (not enough that the string would find the next groove in the hammer) but even with this minimal amount of shift, the shift lever was at the extreme limit of its travel.  It was bumping on the bottom of the keybed.

It was clear that the keyframe stop on the left side of the action cavity had never been shimmed out, and that the hammer shanks were in an appropriate position over the wippen flanges, so everything in that regard seems to still be in its factory configuration. 

Three possible solutions occurred to me.  The first was to affix a temporary shim to the keyframe at the shift lever contact point.  I fashioned a 2mm thick rectangular masking tape shim (about 1" by 1/4") but that may well get scraped off next time the action is slid into the action cavity.  I could pull out the shift lever and somehow bend it to make more travel possible at the keyframe end, or I could fashion a more permanent/durable shim with a taper at the back end to protect it from the shift lever.

It seems odd to me that I should even be encountering such an issue in a piano of this caliber. 

I've been slow in picking up an issue that I now understand has been present for a while.  The Fazioli F278 here at the university has been making a knocking noise when the shift pedal is fully depressed.  As I probed into it, I discovered that the shift mechanism would move the action frame just enough that the trichord hammers would clear the left string (not enough that the string would find the next groove in the hammer) but even with this minimal amount of shift, the shift lever was at the extreme limit of its travel.  It was bumping on the bottom of the keybed.

It was clear that the keyframe stop on the left side of the action cavity had never been shimmed out, and that the hammer shanks were in an appropriate position over the wippen flanges, so everything in that regard seems to still be in its factory configuration. 

Three possible solutions occurred to me.  The first was to affix a temporary shim to the keyframe at the shift lever contact point.  I fashioned a 2mm thick rectangular masking tape shim (about 1" by 1/4") but that may well get scraped off next time the action is slid into the action cavity.  I could pull out the shift lever and somehow bend it to make more travel possible at the keyframe end, or I could fashion a more permanent/durable shim with a taper at the back end to protect it from the shift lever.

It seems odd to me that I should even be encountering such an issue in a piano of this caliber. 

Thank you Don.  The contact area on the keyframe is a hard lubricious plastic, so I'm going to try fashioning a shim out of some acetal copolymer I have on hand, already in an appropriate thickness.

I've been slow in picking up an issue that I now understand has been present for a while.  The Fazioli F278 here at the university has been making a knocking noise when the shift pedal is fully depressed.  As I probed into it, I discovered that the shift mechanism would move the action frame just enough that the trichord hammers would clear the left string (not enough that the string would find the next groove in the hammer) but even with this minimal amount of shift, the shift lever was at the extreme limit of its travel.  It was bumping on the bottom of the keybed.

It was clear that the keyframe stop on the left side of the action cavity had never been shimmed out, and that the hammer shanks were in an appropriate position over the wippen flanges, so everything in that regard seems to still be in its factory configuration. 

Three possible solutions occurred to me.  The first was to affix a temporary shim to the keyframe at the shift lever contact point.  I fashioned a 2mm thick rectangular masking tape shim (about 1" by 1/4") but that may well get scraped off next time the action is slid into the action cavity.  I could pull out the shift lever and somehow bend it to make more travel possible at the keyframe end, or I could fashion a more permanent/durable shim with a taper at the back end to protect it from the shift lever.

It seems odd to me that I should even be encountering such an issue in a piano of this caliber.