I have a client with an SF10 where the hammer bore is 3/16 too short for the string height(definitely looks like original). After some investigation, that "fact" is still in place. The hammers have not been over filed as evidenced by 88 which looks to have a "healthy" amount of felt on top of the molding.

I wonder if I could get from as many people as possible the following information.

1) String height at 1 and 88
2) Key bed to Hammer flange center pin at 1 and 88
3) Hammer bore at 1 and 88
4) Height of the bridge from the sound board to the top of the bridge at 88.

Thanks ahead for your time.

Larry,

Is this an "Accujust" piano? Once Baldwin started using this manufacturing method the height of the strings was measured after the piano was up to tension and bearing set. All the hammers were pre-bored (I believe 1 7/8"Treble, 2 3/16" Bass. The bridges were also pre-cut to a predetermined height and glued to the board which was then installed. The plate height ended up wherever it did with the belief that the bearing could be set within specs on the "Accujust" hitch pins. The height of the action stack was adjusted to fit by the use of shims (to make the action height correct for the predetermined hammer bore distance) depending on whatever height the strings ended up at. Does that make sense?

Perhaps they ran out of the proper shims that day. Or the plate height was grossly out of normal ranges. You will get varying string heights on these pianos because the factory would adjust the height of the stack.

You might want to check the bore distances to verify. Perhaps someone else can verify my bore specs, but I believe I've got it right.

Del? Anything wrong with my thought process or bore numbers?

Well, technically, the frame height was established by a fixed gage set on the keybed. Shims were placed under the pinblock to fix this distance. In theory all of them should have been correct—though I don’t remember what “correct” was just now—and I’m sure some were more correct than others.

ddf

The string height in the one I am looking at is 7 3/4 at 88
The bore at 88 is 1 7/8
HFCP to KB at 88 is 5 3/4

Many have suggested that Baldwin bored for a 1/16 under strike

Based on that criteria, this piano is missing 3/16 somewhere
At the very least, it is missing an 1/8

I don't have my notes in front of me on this particular bridge height.
Hard to imagine there would be bridges of different heights, I am curious to compare here as well.

String height as relates to the treble bridge at 88 looks fine. Lowering the plate 1/8 will produce quite an awkward string angle, I believe the string relationship to the bridge here is correct.

If it is possible to put up measurements from several SF10's, there may be some interesting comparisons.

I knew there were shims involved to fix whatever dimensional issues popped up. Thanks for the clarification.

In theory, the process was a good one and should have resulted in accurate and rapid assembly of the frame to the skeleton. But, as someone once said, “In theory, theory and practice are the same thing, in practice they are not.”

Assuming the dimensions of the bellyrail, skeleton (inner rim in this case), soundboard thickness and bridge height are tightly controlled it should be possible to set the frame (using the V-bar or, in the case of the SF-10 and SD-10, the string termination piece as a reference point) to a standard height off the keybed and have string bearing fall within a very narrow range by placing shims under the pinblock. Any variations in the frame casting and pinblock are compensated for by selecting shims of appropriate thickness.

In practice Baldwin never could quite grasp the concept of making parts to a tight tolerance and rejecting (or fixing) those that were out of tolerance. I was regularly told that since the parts were made of wood it was impossible to maintain tolerances because wood swells and shrinks with changes in humidity. When we in engineering would point out that we were monitoring the temperature and humidity in the factory and that neither had changed appreciably in the last month and therefor the wood dimensions had remained stable so the only remaining explanation was that the parts had been cut incorrectly and not checked we were simply dismissed as not really understanding the reality of production. It mattered not that we could go back to the machine in question and demonstrate that the gage (which had not been calibrated for years) was off, that the parts coming from the machine did not meet design tolerances and that no one had been inspecting anything for months, if not years.

The workers on the line were, by and large, good enough that they were, in most cases, able to compensate for variations in the dimensions of the various components but it took them additional time and effort to do so. And, occasionally the combination of out-of-tolerance parts would add up to a worst-case-scenario and the strings would ride abnormally high on the hitches or some such.

Any protestation that maintaining tight controls over part’s and component’s tolerances fell largely on deaf, if not antagonistic ears. It was an interesting time.

ddf

Thanks Del, confirms my intent for asking the question.

Something accounts for the missing 1/8 of an inch. I am hoping folks will post some measurements from SF10's.

This particular SF10's key frame is all the way in against the cleats in the back and still not able to strike 88 away from the termination enough. I suppose I could add the question of how far the hammers qre hung on the shank. I think the issue here though is the over strike.

I am hoping enough people will post their measurements so we can see empirically the "out of tolerance".

Just keeping this on the 1st page.

Thanks

Larry, am a go for taking some measurements. Now I only have to schedule it around this "Storm" omg, is the press blowing this way out of proportion.

Only minor topic shift here:

I'm wondering if anyone (Del??) could comment on setting the bearing with Baldwin's vertical hitch pins. I happen to be working on an SD-10 at the moment where the bearing was set erratically before unstringing. (Call me cynical, but I'm not overly confident in the setup on any given piano even fresh from the factory.)

Anyway, I'm using a Lowell component bearing gage. My inclination is to go for a net bearing of .012-.015" in the top treble, .009-.012 in the low treble, .006-009" in the upper tenor, and .003-006" in the lower tenor. Bass would be in the .002-.004" range. Except, of course that depending on the where the plate is, you may wind up with negative back bearing with those specs. So that is my tentative proposed setting except I would go with no less than .000" back bearing if that issue should arise.

One tonal oddity on this particular instrument: while the middle few notes of the top treble section speak out brilliantlly, the first and last 5 or 6 notes of that section are weak.

Any comments welcome.

Roy has provided some very importent info here. But I'll second by stating you really need to find out what type of hammers were used in the rebuild. The SF and SD are very sensitive to hammer mating and string leveling, especially if Renner or Abel hammers were used. Any time I start finding zings in these pianos it's always been solved with attention to string and hammer mating/leveling.
I highly doubt it's a bearing issue. From a Baldwin tech sheet:
Some technicians believe that a large amount of bearing is necessary in order to give good tone. The truth is that excessive bearing leads to distortion of the curvature of the soundboard, which will degrade the tone quality and will result in reduced duration of tone. Smaller amounts of bearing give a better tone, particulary for notes whose location on the bridge is near the center of the soundboard. At the factory, bearing is set for each individual instrument. It is not possible to assign values of bearing to be used for all instruments because the correct amount will vary from model to model and to some extent from instrument to instrument of the same model. Typical zero-rock shim thickness values with the Baldwin Bearing Gage may be .01 to .04 in the extreme treble; .01 to .02 in the middle; .005 to .015 in the middle of the treble bridge where the soundboard is most flexible; and .005 to .025 at the tenor end of the treble bridge. Values for the bass bridge may be .005 to .035. Any changes in the value of bearing across the scale should be gradual.
_________________________

Still looking to "collect" as many sets of numbers as I can.
(Outlined in original post)

I am thinking there will be some variations as Del has mentioned.

It will make for some interesting observations.

Kieth, somewhere Ron Naussman emailed me the schedule for setting bearing and bringing the Baldwin accu-hitch up to pitch. I think I can find it and email you, Ron may be willing also.

Is this what your looking for?

Balwin Bearing Gage

Hi Les,

Nice document, I do have those things.

As per my original post, I would like to see as many SF10's measurements posted as possible. The specific measurements I would like to see are mentioned in my original post.

Thanks Les and everyone.

Larry,
Yes, I would like that, if it is additional information from the accujust manual link that was posted. Basically, that says "don't monkey with it" but doesn't say what to do if someone has.

If you send me a PM with your email, I can respond with my email so you can send the info to me.

On another note, there is a significant problem with the rocker gage -- particularly out of the factory: It can lie. That is, you can have net negative bearing but it can still rock, if the soundboard is collapsed and the bridge is rolled enough. The only truly accurate ways to measure bearing is either with a string (fishline or thin wire) or with the component bearing gage using the surveyer's bubble level.

I thought so.

ddf

Ok Larry, went and measured that SD10 today. I also measured the amount of hammer felt from molding to strike point

#1 String height 7 3/4
#88 String height 7 1/2
#88 Key bed to HFCP 5 9/16
#1 Hammer bore 2 5/16
Felt to molding 11/16
#88 Hammer bore 1 15/16
Felt to molding 1/8
#99 Height of Bridge 1 3/16


Model D s/n 167776

Model D

Thank You Les,

Those numbers make sense.

Anyone else .... ??

Calling ALL SF10's .

Larry, am I glad of that...I was starting to think maybe I messed up somehow. I went ahead and got a measurement of how much hammer felt was left, to cover the possibility of excessive filing.

Hey Les,

There is no messing up.

I am also looking for numbers that, although are accurate, do mot make sense.

Larry