The key dip on my upright is between 8.9mm and 11.1mm. I have to choose a key dip, but I don't know. What are the pros and cons of 9.5mm vs 10.0mm? There are no specs for my piano. It's an upright from 1903 and all information is lost during ww2.

    Josephine I'm sorry but I can't answer your question. Do you think there would be any difference between setting your piano to 10mm rather than 9.5mm? In this situation I would go for 10mm.

        keff

        I have no idea to be honest. I started restoring my piano a while ago, but now I realize that I need more experience in playing different pianos. Maybe I should have posted this question in the pianist zone, I'm sure the pianists played a lot of different pianos so it would be nice to hear what they prefer. I read that older pianos had a shallower key dip. But I'm curious of you have enough room for dynamics with a shallow key dip, but maybe that's really a strange thought and there's not a lot of difference. I think I'll go with 10mm key dip.

          9 days later

          The case parts establish extreme limits of key height and dip. Within that, you can adjust to whatever you like.
          You might set three samples at 9, 10 and 11 mm, regulate and compare. Notice you can adjust at each extreme of motion, key height and/or key dip, rest rail and/or let off and/or checking.
          See this video: https://www.youtube.com/watch?v=-MOfvCiRvRo&t=108s