<HTML> <HEAD> <TITLE>Re: [CAUT]  Checking</TITLE> </HEAD> <BODY> Hi Jon,     I generally agree, on new work. Facing a piano with existing parts, in unknown condition, is the scenario I was writing about. Yes, the 2mm or so works well (assuming a standard drop equal to letoff, and measured just as it drops, not with some undetermined, usually too large aftertouch as I seem to find all too often). If you aren’t careful to set up your keyframe to match key dip in the piano, this can be anyone’s guess as a measurement.     Faced with a tail profile that is unknown, one can remove a hammer and do an approximate compass thing using a bit of thread, holding one end about 2.5 to 3 inches along the shank, and with a loop on the other end scribe with a pencil point. But usually I just observe it passing the check on the upstroke to see whether it has a bump and how bad.     And, of course, tail length is what it is. It’s nice to control what you put on, but you also have to try to make the existing part work far too often <G>. Regards, Fred Sturm University of New Mexico On 12/27/06 4:48 PM, "Jon Page" <jonpage@comcast.net> wrote: <BLOCKQUOTE>>there are a few good principles: smoothly curved profile of the tail, no >?bump?; there is a limit to how high the check can be relative to the shank >at rest, and this varies a bit with tail length; angle of check needs to be >within fairly tight parameters, I generally use a 3" arc on the tails. Due to the degree of coving, anything shorter leaves too thin of a tail section. I order hammers un-coved and find the coving process unnecessary. It removes such a minute amount of weight which has a negligible effect on touch weight (certainly not worth the effort). I also ease the 'square' end with a rough file and fine-file the tapered edges to remove 'hairs'. Tail length 1 1/16", shorter lengths brings the check closer and the tops of the back checks can hit the shoulders of the hammers.  I order hammers with a molding 1/8" longer than my longest bore. I then sand all tails to even length after hanging.  Why have varying tail lengths as a result of a tapered bore? Back check height, I have not gone wrong with setting the height to even-with or 2 mm below the tail at drop position. Angle, 72 degrees from key stick. That's the leather face, not the wood rear profile. That's my recipe for success. </BLOCKQUOTE> </BODY> </HTML>