Although a Bechstein grand piano does not come precisely under the
heading of mechanical (automatic) musical instrument, I have some
questions for the engineers out there.
I am researching repair feasibility for an 1891 Bechstein 6' 8" grand
that has three cracks in the plate. It is one of at least three
Bechstein grands with cracked plates in this region (Vancouver Island,
British Columbia, Canada). Apparently this is not an uncommon problem,
and is probably representative of a basic design flaw in the older
The series of articles on this subject by Bob Hohf, RPT, in the Piano
Technicians Journals (Dec 1996, Feb & Mar 1997), was thoughtful and
informative. However, I am not convinced that Bob's theory for the
cause of the cracks is entirely correct, and my initial research
suggests that so-called cold-welding of the cracks will almost certainly
guarantee future failure.
Are there any of you out there who have tackled the Bechstein plate/
pinblock conundrum? I'd appreciate any comments (particularly before
I commit myself to do the job), and would be pleased to supply more
details of the problem at hand (with graphics) to those interested
by private email.
Doug Rhodes, RPT
Victoria, BC Canada
[ As I understand it from Doug, the plate on this transitional design
[ does not encompass the pin block; instead, it has cast-iron 'arms'
[ to which the block is attached. (I hope I have this right.) Humidity
[ extremes might contribute additional stress. What new (and old)
[ techniques are there for repairing broken castings? -- Robbie