Hi Dale They have a machine for doing this these days, largely an automatic process. I believe they mention 10 mm in the middle of the panel gradually tapered out to 8 mm around the perimeters. Hard to see why a piano could come through that didnt have this condition. I did not have time to get all my questions answered, or for that matter think of all the questions I could have, but I got the idea that this thining, along with the feathering was to create a kind of perimeter spring. This would no doubt affect the frequency modes of the assembly as a whole. Perhaps also distribute some of the down bearing load away from the middle of the panel ? Anyways... a clear answer on that point will have to wait until my next visit. On the side, the Hamburg plant is moving increasingly in the direction of automation. Automated machines have been installed in the last 10-12 years for processing the plate, for drilling and notching the bridge, and for processing the rim/pinblock assembly amoung others. They also are using maple for their rims now increasingly getting away from the mahogany used in the past. They get their maple pre-processed from the NY factory, ready made to glue and press into laminates. They put out roughly 4 raw rims a day of different sizes. More as I think of it. Cheers RicB Ron 8 mm /.320ish is on the thin side for a 9ft grand of any make . A board this thin doesn't really need much thinning. In fact it's probably not thick enough in the treble. I'm unaware of the German factory's rhetoric on panel thinning. I'm guessing it sounded a bit thin? grin Regards Dale
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