I recently bought a (japanese) tuning pin torque measure. The values go from 0 to 25 Nm. My pianos pins move with appr. 5 Nm. Do someone know what the ideal Nm for a pin should be?

Convert Nm to lbs/sq.in

Newton-meters should be converted to inch-pounds, not pounds per square inch.

I don't know what it should be. I judge by whether I can get it to stay in tune for a reasonable amount of time or not.

Oops, my mistake. Thank you BDB.

One newton-meter equals 8.850746 inch-pounds. So 50 inch-pounds (about what you want) would be about 5.65 Nm.

I have found that the exact measurement of tuning-pin torque is problematic, due to the way that pins are actually moved in the process of tuning. There is probably a range of torques, perhaps as wide as plus or minus 10 inch pounds, that might be assigned to any one pin.

The bottom line is, as BDB says, whether the piano stays in tune long enough. Probably 50 inch pounds is adequate (plus or minus ten inch pounds) for an older piano. A new piano might have torques well above 100 inch pounds.

Right, Casalborgone. Fifty is just a ballpark acceptable number--in that range and your probably not shopping for a new pinblock. Forty-four (5 Nm) is probably okay, but, as BDB said, the proof is in the pudding--if it holds tune, it's fine.

In a brand new piano, 8nm is considered a reasonable minimum. 5nm should certainly be enough for the tuning to be done well, although 8 - 10 is nicer for the piano tuner to work with. Over 12 is getting a little too tight.

Somebody please tell China and Indonisa 12+ is too tight. They have trouble remembering that.