Pianotech

Could there be a stability issue with an upright using the twin dollies?

With a 2000 Yamaha U5 in a home teaching studio setting, I was told that the technician had passed away and the last two techs the owner tried didn't work out. When I arrived, he added that the bass was never right.

While working on the fairly-close tuning, I did the bass and low tenor, then did it again when I found it off. At some point I noticed the twin dollies. The original casters were off the floor, which I wasn't a fan of as possible noise-makers. The piano rocked somewhat during tuning or heavy playing. I got wondering about the flexing of the instrument into parallelogram shapes and whether it could be an issue. I'll always remember the demo at a class whereby the keybed was sat [leaned] upon while hearing the tuning literally change up and down as we listened.

I had to do this piano yet another time, but fortunately at the end it had remained accurate. The top bass note B-flat was tuned at least [9] times. The owner told me the dollies had been installed when he bought it new. I decided to pop by in a couple weeks -- coming up -- to see how it's behaving.

My question: does anyone have experience or opinions about any effect from sitting up on these dollies? Yes, it's tenuous. No, it's my imagination. Maybe it's possible. Any other words of wisdom.

David Patterson

Well, the piano wasn't designed to have its weight bearing on the bottom board, so there's that. Are the follies securely bolted to the bottom board & the piano frame? Are all the dollies' wheels bearing the weight of the piano?

If you use the Reyburn impact lever while tuning this piano that would help reduce the piano 's wobbling during the tuning. And if they roll the piano after your tuning all your efforts may degrade.