When considering a grand piano I separate these into four categories. Newer but slightly used, used and well maintained, used but need some reconditioning and vintage, and heirloom quality instruments.
In the newer but slightly used category you will find mostly Asian built pianos. I would use a general time frame of under 20 years old. This is true because there are only a handful of American and European manufacturers left. In this category the piano you are looking for is a clean piano that needs no more than a little cleaning, tuning and minimal action work. These are generally bright in tone and have solid actions. As in other industries each brand has its better offerings as well as less desirable models. These pianos are considered disposable as when they get old and worn are usual
There are several considerations in purchasing a piano. Are you looking for the look and sound quality of a grand piano or the space consideration and affordability of a vertical upright? [Console or upright?]
Here are some basic guides that apply to both. Piano strings are generally good for about 50 years. Past that and the wire begins to fatigue and breakage may occur. Also the tuning pins may become loose rendering the piano unable to be tuned. While these problems can be corrected, as a technician, I would rather see the average consumer by a piano that is ready to enjoy, not a fixer upper.
First we need to understand a little history of the piano. While the piano was invented in 1709 by Cristofori, the modern grand became of age in the late 1890’s. This is relevant when we talk