Positioning Plate/Action

[Farrell]

Thanks for your input Ron.

> This work might require more time than
> a small piano is worth. If you are rebuilding a longer quality piano
> it may be worth the trouble. On the other hand, if you're keen to
> learn this stuff without exposing yourself on a high value piano, it
> may be worth the educational experience. After all, getting half paid
> for a job while learning a lot may be worth it.

That right there is the jist of what I am trying to do here. When you really
look close, it is amazing how sloppy some of these pianos were put together!

> I'm doing this very
> thing at present with a sound board modification on a Yamaha G2. To
> those of you on the list who are waiting for the pics of the
> modifications I haven't forgotten you. I expect to be emailing them
> soon.

Could you put me on your list for pics please?

I don't want to modify the action on this one (customer is not paying a
nickel for action work), so I will restrict my play time to the plate.
Jockying things around a bit more in the shop and considering the scaling
factors and strike point, I think I am going to slide the plate back just a
bit and go with a speaking length of about 48 mm. That way I get a strike
point about 3 mm back from the capo (should be OK, plus I have a little room
for keyboard movement/adjustment). I have found that it will also help me
with string/bridge alignment, plate screw alignment, etc. I think all-round
it will work best. I find this actually quite a bit of fun to consider all
these different factors and how they will play out in the end. Maybe after
about 30 years of doing this (hmmmmm, I guess I'll be 76 years old then)
I'll actually be able to process all that in a coherent manner!

But I gotta start somewhere.  :-O

Terry Farrell
Piano Tuning & Service
Tampa, Florida
mfarrel2@tampabay.rr.com
----- Original Message -----
From: "Ron Overs" <sec@overspianos.com.au>
To: <pianotech@ptg.org>
Sent: Saturday, February 03, 2001 11:09 PM
Subject: Re: Positioning Plate/Action


> Terry,
>
> Terry wrote;
>
> >I am trying to optimize plate height and location in a small grand. I
have
> >no idea where the plate was originally (plate was not in piano when I got
> >it).
>
> If you are building new bridges or recapping, then you will be able
> to vary the height of the plate to suit other requirements, such as
> the action geometry, since you will be able to set the new bridge
> heights to obtain the desired down bearing. If you are retaining the
> original hammers, the plate (and in particular the strings at their
> strike point) will need to be located at a distance (height) from the
> key bed to enable the hammer shanks to pass through an optimum arc of
> travel during the key stroke. For example, if the plate is set to a
> lower position than that to which it was originally set (assuming
> that the original setting was appropriate), then the hammers will
> contact the strings with the hammer shanks in a lower position than
> previously. This will place the jack/roller contact further away from
> the line of centers, resulting in increased action friction. If you
> are replacing the hammer set also, you might choose to alter the
> hammer boring distance to set the hammer shanks to an appropriate arc
> of travel for optimal action function.
>
> >The thing was apparently installed originally too high and shifted over
> >toward the bass end.
>
> You may need to determine if the bridges were positioned towards the
> bass also. If so, it may be simpler to reinstall the plate in the
> original position, since the string lines from the bridge to the
> hitch plate may be misaligned if the plate alone is relocated. It may
> be wise to run a thread through the string lines for the first and
> last note of each string section with the plate installed in its
> proposed location, to check the relationship of the bridge string
> sections to the plate. Of course, if you're fitting new bridges you
> will be free to relocate them along with the plate. Furthermore, the
> action stack and strike line may have been installed to suit the
> original misalignment of the plate also. If this is the case, you may
> be creating more problems than you will solve by moving the plate
> across.
>
> >The only area I am not sure what is the best comprimize
> >is up at note 88 (of course!). Having pushed the plate all the way
forward
> >in the case, I have a speaking length of 52 mm and a strike point about
9.5
> >mm from the termination point at the capo.
>
> A 52 mm speaking length at C88 will work, but the strike point at 9.5
> mm from the capo will not allow the note to speak effectively. Our
> 225 piano has a C88 speaking length of 53 mm. We found that the
> strike setting which produced the highest sound pressure level was
> between 2.5 to 3.0 mm from the capo', optimally 2.75 mm. If you
> position the plate for a 52mm speaking length, you will be unable to
> move the keyboard enough to correct the strike, since it would run up
> against the key slip, and there would be excessive clearance between
> the fall board and the black notes. While alternatively you could
> reduce the hammer shank length by 6.5 mm to arrive at a satisfactory
> strike, this is a major change (there may be insufficient space
> between the hammer moulding and the hammer stop rail). You may find
> it easier to move the plate away from the stretcher by at least 3 mm
> to reduce the C88 speaking length to 49 mm which will bring the
> hammer strike point back to 6.5 mm from the capo' (Steinway Hamburg
> historically set C88 at 53 mm in the D - the most recent D we
> measured [circ. 1999 piano] had a C88 length of 49 mm). You may then
> be able to correct the strike by mounting the hammer 3.5 mm along the
> shank towards the center (I am assuming that the optimum strike
> position is 3mm - this will need to be verified by moving the action
> backwards and forwards as the note is struck).
>
> >If needed, I can slide the plate
> >toward the rear about 5 mm, which would then give me a speaking length of
47
> >mm and a hammer strike point about 4.5 mm from the capo. I probably could
> >move the action a little bit, but I am pretty sure that the action is
> >sitting where it was supposed to, or at least where it originally did -
and
> >I'm not sure how it would work with the fallboard - I have about a 3 mm
gap
> >between the keyslip and the key front.
> >
> >Anyone have any input on whether I should go with a 52 mm or a 47 mm
> >speaking length? Or best way for me to decide?
>
> Be aware that repositioning the plate will also alter the string
> scale. For some instruments, which might originally have been strung
> beyond a safe percentage of breaking strain in one or more string
> sections (anything over 60% is already in the danger zone), further
> lengthening of the string scale (by moving the plate toward the
> stretcher) might aggravate a likelihood of string breakage. When
> considering a possible plate position, it may be good policy to
> measure the first and last speaking length of each string section,
> graphing them on a speadsheet to determine the percentage of breaking
> strain. You might also wish to investigate the inharmonicity effect
> of any plate reposition on the scaling, although this is getting
> beyond the scope of a straight repair and into customising -
> nontheless it is an interesting area to get into. With the setup in
> your particular piano, it would seem more appropriate to set the C88
> speaking length to a lesser length if possible (say 49 mm), to
> minimise the necessity of major action changes.
>
> >If it is likely that the 52
> >mm speaking length and 9.5 mm strike point combo is right in the
typically
> >good functioning ballpark, I'd rather stick with that - it will be
easiest
> >for me.
>
> As mentioned earlier, I doubt that a 9.5 mm strike will work with a
> 52 mm speaking length. While you could shift the entire action stack
> on the key board to retain the 52 mm speaking length, positioning the
> hammer to the optimum strike point without altering the shank length,
> this would involve a recalculation of the action geometry between the
> key and wippen. A new wippen heel depth would be required and the
> capstan and wippen heel would require relocating to satisfy the
> action geometry requirements. This work might require more time than
> a small piano is worth. If you are rebuilding a longer quality piano
> it may be worth the trouble. On the other hand, if you're keen to
> learn this stuff without exposing yourself on a high value piano, it
> may be worth the educational experience. After all, getting half paid
> for a job while learning a lot may be worth it. I'm doing this very
> thing at present with a sound board modification on a Yamaha G2. To
> those of you on the list who are waiting for the pics of the
> modifications I haven't forgotten you. I expect to be emailing them
> soon.
>
> All the best with the project Terry.
>
> Regards,
>
> Ron O
> --
> Overs Pianos
> Sydney Australia
> ________________________
>
> Web site: http://www.overspianos.com.au
> Email:     mailto:ron@overspianos.com.au
> ________________________
>