consistent downbearing measurements

[Dan McElrath]

Might as well get my feet wet here.
As we all know, in the tremendous battle of string and plate vs a 3/8ths board with ribs and
crown the weaker board will eventually submit. I measure bearing on every grand I service with
a simple brass gauge from Schaff, more for reference than anything else. It has been interesting to note that generally a piano with "comparatively" (That is compared to the many other pianos I service) good bearing will, as a rule, have more power and sustain than those with little or none. It has also been of interest that most pianos will have varying degrees of bearing depending on where you measure along the bridge and, again, differing measurements from bass to treble bridge on the same piano. I cannot confirm this with scientific accuracy as of yet but it appears that there is generally a direct correlation between lack of bearing and weak tone in a particular area of a piano.(i.e. many pianos have very poor tonal characteristics at the end of the treble bridge, crossing over to the bass. Very often, little or no bearing exists at this spot on the bridge. More than a coincidence, I think.)
I once asked John Patton at Steinway how long they believed a soundboard in a concert "D" would maintain peak crown before becoming "tired". He replied, "About 5 years." The drop off is slight but usually measurable in 5 years.
It is true that I have occasionally seen pianos with little or no bearing that seem to have strong power and sustain. I cannot account for this anomaly except to say it appears to be the exception rather than the rule.
Any input by rebuilders here would be most appreciated. I often wonder how often techs unknowingly are trying to compensate for poor bearing by over or under voicing hammers. As an aside, since we have such huge climactic extremes here in Alaska I have also noticed the bearing changes noticeably from winter to summer and that making harmonic analysis with the Pianalyzer indicates noticeable changes in power, sustain and harmonic makeup from season to season on a given tone of a given piano. Some attributable I'm sure to hammer changes as well.
On that never ending search...........
Dan McElrath, RPT
Alaska Piano Services