key depth: 3/8" or 1/2"?

[faulty_damper]

On my Yamaha grand GH1, the depth of the key when depressed in about 1/2" but I read in a piano maintenance book that it should be 3/8".  So I added some cardboard punchings under the keys to make it 3/8" and it made a significant difference in touch and it seemed lighter, too.

So is there an appropriate key depth?

[cysoto]

Some people like the longer key travel.  I guess you can have more control over your tonal expression.  I favor the shorter (and lighter) action but this is nothing more than a matter of personal preference.  I can play some passages faster but I have to sacrifice volume (I guess my neighbors are greatful for this). 

You can have your technician work on the action to change that.  It will certainly last longer than the "cardboard" trick.

[faulty_damper]

Well that's what these punchings are made out of, cardboard or thin pieces of paper to level the keys when depressed.  I'm my own piano technician and was just wondering whether or not it should be 3/8".  At more than this depth, there is a lot of wasted motion because the hammer has already struck the strings.  I guess it should be at 3/8" as I have yet to find any contradicting depth.  So now I need more cardboard and paper punchings.

[G.Fiore]

 FD,  I hope you realize that by playing with key dip you are now also messing up the after touch that was set at the factory. By the way, key dip as specified by Yamaha is 10 mm on all grands.
 Hire a professional,  you're piano will be much better off.
 

[faulty_damper]

10 mm is only .5mm deeper than 3/8".  I'm sure the piano in the original state 10+ years ago was at 3/8" and that only the felt punchings have worn down due to compressing by years of use.

What do you mean by aftertouch?  You mean the repetition lever height?  I've readjusted those as well as the felt has been compacted from years of use.