Knabe(Samick)/Renner & the 114 mm action spread

[Ron Overs]

Hello John,

The 114 you have measured is exactly on spec for the Knabe and NSG 
Samick grands (the Renner action is typically set at 112 mm as you 
mentioned). I have the CAD drawings of these Samick models at my 
office.

The blow distance should be checked first since, on a new instrument, 
it is one of the first action parameters to go out of spec. The 
standard blow distance is 47 mm, but on a new piano I would adjust it 
to 45 provided that it doesn't make the after touch totally 
excessive. There will be quite a bit of settling of the knuckles when 
the action is new, so it won't take any time at all for a 45 mm blow 
setting to become 47. I don't know what the hammer/key ratio is in 
the later Samicks. The earlier pianos of a few years ago were running 
very low ratios. They often needed well in excess of 10.5 mm to 
achieve a respectable after touch.

Do some experimental regulation on C40 (middle C) to see what works. 
I'd recommend setting it with a 45 mm blow distance and adjusting the 
dip until you achieve the jack just clearing the knuckle leather in 
check. Don't forget to check that the let off is around 1 mm and the 
drop between 2 to 3 before checking the after touch (the let-off in 
particular will change the after touch). I like to set the check at 
around 12 mm if possible for faster repetition, but the current 
Samick tail lengths are a bit short for that, so 14 or 15 might work 
better.

The jack cushions might be too thick as well. Ideally, the jack 
should come into contact with the jack cushion just after it loses 
contact with the knuckle.

Ron O.

>I was prepping a new Knabe with a Renner action and found it had no 
>aftertouch before the jack hit the cushion. I measured the spread 
>and it was 114mm which put the knuckle so far forward that there is 
>no way to get any real aftertouch.
>
>I thought the Renner action was pretty much a 112mm (+/-) action. 
>This action would certainly perform well there. Did Samick do this 
>to be "consistent" with there other actions or what?
>
>Scratching head,
>John
>
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-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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