It certainly appears (though I can't figure out WHY) that these specs were variable back then (it negates the fundamental principles of manufacturing in general) as I have a 1970 L that came into the shop with 15.5mm knuckles, gigantic heavy hammers, keys leaded to the max, sharps so narrow that your fingers fell off of them (if in fact you could play on it longer than 5-10 minutes without developing tendon problems)...
This instrument is now playing pretty decently with its original parts (except for strings, agraffes (they were a mess), dampers, and sharps (ebony and wide harvested from an old Chickering). It would be even better if there was another .5mm on the knuckle spec, but c'est la vie.
And BTW, if you have tight Teflon bushings, a drop of TSI 321 on each side should free them up nicely. (321 is the same as 301 but without the solvent...recommended by the manufacturer when plastic is involved). I used this on B to good advantage.
Original Message:
Sent: 04-24-2025 09:29
From: Bill Ballard
Subject: Steinway knuckle spec
Parker went: "I was trying to make the point not to assume anything when it comes to NY action specs but to examine each piano individually."
An excellent point, thank you. I was just curious about the particular case where 15mm kmd was the solution. Normally. in this age of 18# hammers, 15mm kmd is the problem.
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William Ballard RPT
WBPS
Saxtons River VT
802-869-3161
"Our lives contain a thousand springs
and dies if one be gone
Strange that a harp of a thousand strings
should keep in tune so long."
...........Dr. Watts, "The Continental Harmony,1774
Original Message:
Sent: 04-24-2025 09:18
From: Parker Leigh
Subject: Steinway knuckle spec
I was trying to make the point not to assume anything when it comes to NY action specs but to examine each piano individually.
Hamburg Steinway tend to stick more closely to the 1880 patents.
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Parker Leigh RPT
Winchester VA
(540) 722-3865
Original Message:
Sent: 04-24-2025 08:56
From: Bill Ballard
Subject: Steinway knuckle spec
Peter Grey went: Can you explain the actual function involved in raising the stack beyond what I would imagine is the position of the capstan relative to to the whippen cloth? I have not given this much thought over the years.
If you raise the stack, the combination of the higher capstan and shank center subtracts from the blow distance. So you need to back off on the capstan.
Parker went: "I remember Rick Butler telling me that he had to use shanks and flanges with 15mm knuckles to correct terrible playbility."
Which begs the question, "what exactly was the terrible playability"? Was it "fly away hammers" (extremely light hammers on a high Strike Balance ratio, which accelerate so quickly that the pianist loses control of them)? Was it the extra "start-up costs" (inertia) from a set of 16# hammers? These two are opposite examples of unplayability. To gain any wisdom form his remark, we'd have to know what kind of unplayability he was dealing with in that one situation.
With an idea where the results are unknown, I work on the basis of samples. So, reset the stack location and regulate one note (- I'd pick a heavy hammer note in the bass). Also be very careful of confirmation bias.
------------------------------
William Ballard RPT
WBPS
Saxtons River VT
802-869-3161
"Our lives contain a thousand springs
and dies if one be gone
Strange that a harp of a thousand strings
should keep in tune so long."
...........Dr. Watts, "The Continental Harmony,1774
Original Message:
Sent: 04-24-2025 07:59
From: Peter Grey
Subject: Steinway knuckle spec
Will,
Yes, that will be on the docket for the next round of improvement. Can you explain the actual function involved in raising the stack beyond what I would imagine is the position of the capstan relative to to the whippen cloth? I have not given this much thought over the years.
Edit: the jacks are SLIGHTLY forward of 90 degrees. If the knuckles were at 16mm it would be 90 degrees.
Peter Grey Piano Doctor
------------------------------
Peter Grey
Stratham NH
(603) 686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 04-24-2025 04:13
From: William Truitt
Subject: Steinway knuckle spec
What is the knuckle alignment showing? What do you see?
Yup. If you change the stack height, you will be doing a fair amount of re-regulation. Even if you are not going to reset the stack height, it may be instructive to take the measurement and see what it is in this problem beast. When I come to a problem piano even for just a regulation, I take the measure upfront before I begin. More than once I have begun the regulation after resetting the height. Most of the time, the stack is too low. I can quick and dirty throw a maple veneer shim or two onto the top of the keyframe, regulate a note or two in that area; slide the action in, get some feedback, and proceed accordingly. Sometimes this can make a night and day difference, others the change is small but still meaningful.
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William Truitt RPT
Bridgewater NH
(603) 744-2277
Original Message:
Sent: 04-23-2025 17:57
From: Peter Grey
Subject: Steinway knuckle spec
Too late for that. Maybe next time.
What I will say though is that the way that the jacks align with the knuckles, another .5mm to 1mm in the knuckle spec would serve them well. Alignment would be ideal, and I bet touchweight would come to near normal and some lead could be removed from the keys.
Peter Grey Piano Doctor
------------------------------
Peter Grey
Stratham NH
(603) 686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 04-23-2025 16:51
From: William Truitt
Subject: Steinway knuckle spec
What is the stack height, Peter? Measure shank center pin height, whippen center pin height carefully.
------------------------------
William Truitt RPT
Bridgewater NH
(603) 744-2277
Original Message:
Sent: 04-23-2025 11:52
From: Peter Grey
Subject: Steinway knuckle spec
Update:
In rummaging around in my parts drawer I actually found other (Renner) shanks with tge same 15mm spec, so I guess it's not as unusual as I thought. Anyway, a couple of days of recon work has improved the playability of the piano such that the owner is very pleased. Still, if I were to attempt to bring the touchweight down below 65g (where it is now) without adding more lead to the keys I think new shanks and all would be in order.
So far things are improving. She's happy, I'm happy...everybody's happy (at the moment). 😉
Peter Grey Piano Doctor
------------------------------
Peter Grey
Stratham NH
(603) 686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 04-23-2025 11:11
From: Parker Leigh
Subject: Steinway knuckle spec
I remember Rick Butler telling me that he had to use shanks and flanges with 15mm knuckles to correct terrible playability. Perhaps due to topstack geometry.
Use a line card guage and calipers to more accurately measure action spread. You may need to indent pins slightly to due this.
------------------------------
Parker Leigh RPT
Winchester VA
(540) 722-3865
Original Message:
Sent: 04-22-2025 10:22
From: Peter Grey
Subject: Steinway knuckle spec
113mm Pretty close I think...
Peter Grey Piano Doctor
------------------------------
Peter Grey
Stratham NH
(603) 686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 04-21-2025 21:08
From: Parker Leigh
Subject: Steinway knuckle spec
During that timeframe Steinway specs could vary greatly. Have you checked the action spread?
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Parker Leigh RPT
Winchester VA
(540) 722-3865
Original Message:
Sent: 04-21-2025 20:19
From: Peter Grey
Subject: Steinway knuckle spec
I have a 1969/1970 B here with a center pin/knuckle core spec of 15mm. The shortest I've ever measured is 15.5mm and that is on very old ones with very light hammers.
Has anyone else encountered a 15mm spec on a Steinway anywhere?
Incidentally, as you can imagine the touchweight is VERY high, over 70g in the bass and 60's elsewhere. Several hours of reconditioning today has brought it to about 60-65g bass and 60 or less elsewhere. The instrument is a POWERHOUSE and the owner is used to the weight and loves the power she can get out of it, but I was quite shocked to see this measurement on a piano of this vintage. Keys are leaded accordingly.
Anyway I'm just curious if this is a rare instance or just something I haven't ever noticed before. 🤔
Peter Grey Piano Doctor
------------------------------
Peter Grey
Stratham NH
(603) 686-2395
pianodoctor57@gmail.com
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