Action flange crushing

[Phillip Ford]

>inthe early days i remember ptg convention classes and instructor told
>about 18 lbs torque for hammer and whippen screw.. i got a torque wrench
>and practiced a little and anybody can get that feell.. it works.. a few my
>collegues came to my shop and practiced with torque wrench to get that
>feel.. try it!!

Isaac,

     Thanks for the response.  This is exactly the sort of info that I 
was looking for, and for the reason that you give.  It seems to me 
that this would be useful information for techs (especially beginning 
techs) so that they could calibrate their hand (or wrist), so to 
speak.  If it really is important for the flange to be as tight as 
possible, but not crushed, then it's surprising to me that someone 
(factory or action manufacturer) hasn't published a torque spec. 
Also, I would assume that there could be some relation between screw 
torque and long term tightness of the flange, and that some factory 
would have investigated this.  My assumption would be that tighter 
would be better for long term flange tightness, but I've done no 
experimenting to prove this.
    I contacted several factory service departments about this.  Not 
one had a torque spec.  This response from Schimmel might be 
considered representative (I'm paraphrasing slightly as I don't have 
the response in front of me):

Thank you for your interesting inquiry.  We rely on the trained hands 
of our factory technicians to make the screws tight enough but not 
too tight.  This has worked for us for 120 years.

They then referred me to Renner.  Who then referred me to Renner USA. 
Who then referred me to Rick Baldassin.  Who then told me that he 
wasn't aware of any such spec.  He did say that years ago he attended 
a class given by Baldwin in which they had a torque measuring 
screwdriver and demonstrated what they considered to be appropriate 
torque.  Anyone out there attend that class?  Do you remember the 
torque number specified?

Interesting that you have the number of 18 lbs (is that 18 in.-lbs, 
by the way?).  One factory rep told me, off the record, that he 
believed that 12 in-lbs would crush a maple flange.  Also, Guy 
Nichols seemed to recall that the Baldwin factory used 10 lbs (10 
in.-lbs?) for action screws.

As soon as my desire for information becomes stronger than my 
resistance to paying $160 for a torque measuring screwdriver I'll 
measure some torques myself.  If so I'll report back.

Regards,

Phil Ford

-- 
Phillip Ford
Piano Service and Restoration
San Francisco, California