Jeff,
Now that we know some facts, raising the action is the way to go. The original bore of 48 mm appears to be more or less standard, thus "correct" as processed at the factory. So one wonders what happened when it came time to set the action stack height; or is the pinblock and entire string plane set too high.
No matter. given your data, it may be that you need not turn the capstans up terribly far after you reset the stack. Think of it this way. I assume that you set a blow to 44 - 46 mm in your recent regulations.
(If not, then I cannot imagine what else you might have done, in which case ignore most of what follows).
In order to set a workable blow relative to (what we now know to be) a too-low sitting stack and / or a too-high string plane (unlikely I guess), you must have already turned the capstans up beyond some normal range. Now as a thought experiment imagine things as they are and with the blow set to 45 mm; now imagine that the stack screws magically unscrew and remove themselves after which the action stack floats upward off the frame and off the capstans by 6 mm, but the rotational components stay locked, i.e. the whippen and hammer shank do not drop. You can visualize that your blow distance is now too short by 6 mm requiring you to "lower the capstans" so as to regain your 45 mm blow distance. So the jury is out as to how much capstan movement or extension will be necessary.
RE your touchweight. Friction does not seem to be an issue, but as Jon has pointed out the DW is too low.
But you cannot trust these measurements at this time and you will need to take new DW UW tests after the blow is reset. You did not report on any visual per the action component configurations after you regulated the action. Specifically, in order to set the blow to 45 mm in the current setup, the whippen beam would have had to rotate beyond level (many whip beams at rest sit 1 degree or so below level). But more importantly the hammer shank and knuckle would have rotated by something like 2.5 degrees, and this is at rest. The jack at the knuckle, at rest, will not be interfacing at 90 degrees but at greater than 90 degrees, and it is in this little pocket of first rotations (first 2 mm of key dip) where inertia and friction are the highest.
Well, anyway, given all these mind games you still may find the DW UW BW FW friction thing not right so hold off on that TouchRail, especially given that this device's primary function is to lower DW on a heavy system and cannot be used to raise DW (as far as I know). Measure touchweight again later and report. If later reports continue to show a too-light DW the "correct method" is to remove portions of the key leads (hope to see you at WestPac where I am giving a class on an accurate way to do this that eliminates guesswork and messed up keysticks).
Since you should have the action at your shop for adjusting the stack height and roughing in a regulation at the bench, that would be the time to address resetting the leads. But if whippen assist springs exist, adjusting these might be a partial if not complete fix.
Jon also mentioned the HCH dimension as it relates to the WCH dimension of 64 mm; this is an interesting dimension that doesn't normally surface in these discussions. The 64 mm (63.5 mm actually) dimension is the vertical distance down from the hammer center (HC) to the Whippen Center (WC) and exists in the stack irrespective of the the keybed or string plane. This dimension is difficult to measure as it is one of the rectangular components of the spread, and thus the spread dimension is the practical one. There are only two ways or a combination of the two to change the spread. One is to adjust the whippen rail in or out, or to adjust it up or down or some combo.
So, if you make sure that the capstan centers on the the whippen cushion (more or less a tad) then your horizontal component is basically in place (something like 94 mm but also difficult to measure) and this is a starting point. Now given a 63.5 mm vertical drop and 94 mm run the diagonal action spread works out as the hypotenuse to 113.5 mm. The spread is relatively easy to measure so go from there and take heed of Jon's remarks as to jack top excursion. If the spread is not 113 or so then a whippen rail adjustment may be called for. Again, report back later.
nick
-------------------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net 928-476-4143
-------------------------------------------
Original Message:
Sent: 02-06-2015 00:39
From: Geoff Sykes
Subject: Looking for tips to lighten the touch
I serviced this piano today and here is what I found.
String height note 40 = 203mm : flange center = 148mm :: difference = 55mm :: bore = 48mm :: difference = 7mm
String height note 60 = 201mm : flange center = 148mm :: difference = 53mm :: bore = 48mm :: difference = 5mm
The grooves in the hammer are most definitely showing on the back side of the hammer. They pretty much stop at the center point. This demonstrates to me that the hammers are overstriking and the stack needs to be raised.
Clearance from top of flange screw to bottom of stretcher is about 11mm.
Based on what I believe I've learned from this discussion, current plan is to raise the action stack by about 6mm and re-regulate.
Question: Can I use something as simple as washers on the screws to shim this up, or do I actually need to make a shim that will run full length between the front and the back screws of the action brackets? Is wood OK or should this be metal?
Touch weight:
Full regulation about a year ago. All friction points have been checked, lubed, teflon lubed, eased, etc. Knuckles and jacks are aligned correctly. This is current touch weight on two notes, with dampers lifted. (Sadly, I did have to "depress" the sustain pedal to accomplish lifting the dampers.)
A3 : DW = 40g :: UW = 12g :: difference = 28g
A4 : DW = 39g :: UW = 19g :: difference = 20g
Not to forget that this is a three year old entry level Knabe, by Samick. The plan is to re-evaluate touch weight again after the above action work is completed. If there is no significant improvement then I am thinking of keeping it simple and going with a TouchRail system. According to Scott Jones, this should allow me to reduce the DW by up to about 10g with no problems.
Looking for further comments on this project.
Thanks everyone.
-------------------------------------------
Geoff Sykes, RPT
Los Angeles CA
-------------------------------------------