Grand piano design - parallel vs angled strike line?

[Roger Jolly]

Hi Ron,
            You should have labled the title, fudge factor 101.
One  variable you omitted, inertia is also being reduced as you move up the
scale since the hammers are smaller and the key weights are being moved
back.  How much effect does this have with regards to perception, feel, and
actual action saturation?
So many of todays pianos have soft wood frames,  bedding is very critical
in the treble, for both tone and feel. Yamaha concert grands need bedding
each time you tune them, for optimum performance.
More questions?????
Most concert grands have reduced treble shank mass, for tonal reasons.
Adding to the balance problem.
Good quality maple shoes can negate the effect of key whip lash, and lower
saturation. Like you I'm skeptical about the idea of shortening the key for
stiffness reasons.
How much is deep rooted tradition, and how much is science?  Good question.
I suspect that once the scale is set and the plate is cast,  make it work
enters the picture.
Brian has a good point about the belly rail. Start messing with it, now we
need to look at under levers etc.
Now, is the dog leg in the leading edge of the board/belly rail, there to
accommodate the treble strike point, or the bass strike point.  How many
empirical experiments were conducted to arrive at this configuration?  As
an aside, I have noted that many cracked boards, start to crack at the
corner of the dog leg.
Are we prisoners of tradition?
No answers, just more questions 

 
Some thing else to muse over for the week end.
regards Rambling Roger




At 06:38 PM 09/12/00 +1100, you wrote:
>To those commentators on piano design, and other interested lurkers,
>
>While it is generally accepted that the hammer strike line should be 
>parallel to the front of the key bed for smaller grands, the 
>situation is not so universally accepted for longer pianos.
>
>I have raised this issue with piano designers over the years and 
>there is some variance of opinion. Obviously, a shortened treble 
>layout will position the treble tuning pins closer to the tuner (this 
>may certainly be an issue for a 3 metre piano), but is this the 
>primary reason for shortening the treble end keys, and what are the 
>negative outcomes of such a design regime?
>
>Recently, one designer claimed that shorter keys are necessary in the 
>treble for the tone. He claimed that the resultant stiffer treble 
>keys (of the angled strike-line pianos) assist with the feel of a 
>'crisp' treble. I remain a sceptic, since the hammer mass is less in 
>the treble. Therefore the treble keys should appear to be relatively 
>stiffer than those of the bass (even if they are of the same length 
>and depth), since note C88 will be lifting a hammer which is often 
>40% lighter than the first bass hammer.
>
>Kawai, Fazioli, Steinway and Yamaha all shorten their treble end 
>concert-piano key lengths (by as much as 75mm or 3"), while 
>Bosendorfer persist with a non-angled strike in their 9'6" Imperial 
>model. Certainly an angled-strike regime complicates the geometry 
>setup for the wippen heels (most, if not all angled-strike adherents, 
>seem not to make any adjustments). Ideally, when the strike is 
>angled, the wippen heel depth should be greater for the shorter 
>treble keys (if the contact between the capstan and heel is to remain 
>on the fulcrum line at half dip). Therefore, if we are to produce 
>wippens with idealised heel dimensions from bass to treble, for 
>angled-strike-line pianos, the heels should vary in height from bass 
>to treble accordingly. Such a heel set could be made from a specially 
>tapered piece of stock prior to sawing them to width. When the strike 
>line is parallel, no such geometry problems are encountered. While a 
>parallel strike will place the treble tuning pins some distance away 
>from the tuner (as already mentioned), the extreme treble is more 
>likely to have a smaller sound board area between the bridge and the 
>adjacent outer rim - a desirable design objective I would think. Some 
>might consider using a greater dead-string-length between the capo 
>bar and the tuning pins as a solution with the parallel-strike 
>design, but excessive length here would surely encourage rendering 
>and tuning stability problems.
>
>Your views I await.
>
>Ron O
>-- 
>
>_________________________
>
>Website:  http://www.overspianos.com.au
>Email:      mailto:ron@overspianos.com.au
>_________________________
> 
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505