Soft Volume After Replacing Missing String?

Posted by: miscrms

Soft Volume After Replacing Missing String? - 02/08/13 05:23 PM

Hi all, wanted to see if anyone had any thought on this?

When we acquired our piano it was missing one string, leaving only one of the tri-chord strings in place on the A4 key. It had apparently been like this for some time, as the single remaining string had cut a little deeper groove into the hammer than the grooves of the two missing strings.

The existing strings are quite old (could be as much as 139 years, but hard to say exactly) and measuring the adjacent strings with a digital micrometer was difficult to get consistent results. Down in the speaking length I saw as little as 0.0355, but up near the tuning pin I saw no less than 0.0365. Assuming the string was stretched due to age, and that the top measurement was more accurate, I ordered some #16 Roslau / Schaff wire to replace.

The replacement seemed to go well, though it was my first, coils are fairly neat, square and tight, the agraffes seem to help hold the strings pretty much in the same position / spacing as the originals, and I did attempt to "set" the strings on the bridge pins with a hammer and screwdriver held parallel to the direction of the wire. After several days of regularly stretching the wire up to ~ 30c sharp, it seems to be holding pitch pretty well now that its tuned.

The weird thing is, the volume is noticeably softer than it was when there was only one string. I think due to the mismatched grooving in the hammer its possible that its only striking the two new strings now, but I'd still expect two strings to be louder than one string was. Also interesting, for reasons explained elsewhere I replaced two of the three tri-chord strings on B4 very nearby with the same wire and method, and it sounds fine.

Any thoughts?

Thanks,
Rob
Posted by: Blues beater

Re: Soft Volume After Replacing Missing String? - 02/08/13 06:15 PM

Hesitate to answer because I am only a DIYer, but did you consider filing the hammer?
Posted by: Eric Gloo

Re: Soft Volume After Replacing Missing String? - 02/08/13 06:30 PM

Originally Posted By: miscrms
It had apparently been like this for some time, as the single remaining string had cut a little deeper groove into the hammer than the grooves of the two missing strings


Sounds like the hammer is only striking the new wire, with a less-used part of the hammer...causing a softer volume. With the damper pedal depressed, hold the hammer against the strings and pluck each string with a guitar pick, or a wooden pick. The original string will probably sound, while the 2 new strings will not. You'll need to reshape that hammer so that it strikes all 3 strings at the same time. However, it may or may not end up sounding brighter than the neighboring hammers...so some voicing might be needed on that hammer.
Posted by: miscrms

Re: Soft Volume After Replacing Missing String? - 02/08/13 07:21 PM

Ok thanks. That's kind of what I figured. I'm learning a lot of new things here all at once, and was hoping to wait a little bit until tackling hammer shaping wink I guess that's kind of how it goes with an old project piano. The piano often tells you what you will be learning next smile

Rob
Posted by: RestorerPhil

Re: Soft Volume After Replacing Missing String? - 02/08/13 07:41 PM

..."old project piano"...


Not to worry.


You already have one.
Posted by: miscrms

Re: Soft Volume After Replacing Missing String? - 02/09/13 12:13 AM

BTW here is a picture of the general degree of grooving in the hammers. The A4 hammer in this view is the third one heading left from the left action bracket. You can see the left most groove is definitely deeper. I'll link to that one at a large size so as to show some detail w/o bogging down the thread.

http://farm9.staticflickr.com/8464/8440914422_2d0441a675_h.jpg

and a few of the profile views.




I'm assuming those can't be original, but I don't know. They seem like they still have a good amount of felt on them, but on the other hand they are already about 2" off the strings. I'm guessing that has more to do with some issues in the action (worn felts?) as the stickers are mostly regulated all the way up and there is still significant lost motion between the jacks and butts. The hammer shanks almost all bounce pretty hard on the hammer rail on their return.

Rob
Posted by: Olek

Re: Soft Volume After Replacing Missing String? - 02/09/13 06:43 AM

largely enough felt, then we did not see the strike .

you dont have to shape the hammer if it goes right on the strings (unless the piano was played for long with only one string there)

just massage the wire to adapt its plane to the hammer. but verify the strike location.

New wire of course make a less harsh tone than old one, it is less hard, so the tone is different, fuller, usually.

some hammers are not centered, if you can shape them enough you can move them)

You could space the dampers too, they look ugly
Posted by: Mark R.

Re: Soft Volume After Replacing Missing String? - 02/09/13 08:21 AM

Rob,

I broke one string on a bichord in my piano a few years ago, and played for a few weeks with only the one string. When I knotted the broken string, the note was very dull, almost fuzzy. I didn't re-shape the hammer, however, because the grooves were still more or less equally deep. I decided to observe things without touching the hammer, and the normal timbre of the note came back after a few hours of playing.

But your case is different. The linked photo clearly shows that the left string of A4 has left a much deeper groove than the other two. (Also, the grooves don't seem very well centered on the strike point.)

In my opinion, your piano was played for a prolonged period with only the left string on A4. I am no professional, but I would humbly suggest gently re-shaping that hammer to achieve more even mating between the hammer and all three strings.
Posted by: David Jenson

Re: Soft Volume After Replacing Missing String? - 02/09/13 09:07 AM

On the reshaping and voicing, less is better at this juncture until the hammer has some time to adjust.
Posted by: miscrms

Re: Soft Volume After Replacing Missing String? - 02/09/13 11:17 PM

Thanks all for the thoughts. Much appreciated! I verify that with the hammer forward against the strings and the damper raised that the two new strings are damped by the hammer but the old left hand string rings clean.

Will probably just live with it for now, but looks like hammer shaping will have to move up the project list. It was fairly inevitable, as a number of hammers are not quite hitting evenly but the grooving seems significant enough that I can't really address that until they are cleaned up. As Issac pointed out the to do list on this old piano is rather long smile

In the mean time, we're really enjoying having a piano in the house warts and all wink

Rob

Posted by: Mark R.

Re: Soft Volume After Replacing Missing String? - 02/10/13 08:51 AM

Rob,

Having limited experience, I gladly defer to what David Jenson wrote. Wait and see/hear.

Also, another thought came to my mind: reshaping, string mating and voicing makes limited sense if some of the hammer flange bushings are worn/loose, i.e. if the hammer is not being guided towards the strings in a controlled fashion.
Posted by: Olek

Re: Soft Volume After Replacing Missing String? - 02/10/13 09:35 AM

the new wires can be massaged so to line with the old one , just massage on some lenght while pushing on the wire, it will lower.

the dampers can be straightened with flat pliers or even with your fingers, but the wedged ones may be correctly placed so only the flat ones are easy to straighten.

To have an optimal tone on a vertical it is often necessary to change all the hammer centers for new ones one size thicker.
Mostly to obtain an even friction and no wobble (vertical shanks are flexing more than grand shanks)
It could be done by an DIY after some testing, so only one size of centers may be necessary, but then reinstalling the flanges and papering them is not so easy (and sometime the original papering is not glued, anyway there is always some shank traveling work to be done)


as pointed Mark shaping heads is good but the hammers may not move on their axis

WHen filing vertical hammers it should be advisable to file a little more the underside so to keep the original strike, even if the point of the head is a little non centered then.test should show if the tone is better.
Posted by: miscrms

Re: Soft Volume After Replacing Missing String? - 02/19/13 03:57 PM

Just wanted to report back that the hammer filing suggestions were right on. This particular hammer seems to travel true without wobble, unlike one of its neighbors.

I've been taking it very slow and gradual, using a combination of a finger nail file and a 150 grit sanding stick. I've been working from the shoulders toward the strike point in an arcing motion counting strokes to keep an even number of strokes on each side. Occasionally after picking the fuzz from the strike point I'll do a few rocking back and forth strokes across the front to smooth out any ridges that start to form near the ends of the longer strokes. Its slow going, but I'm trying to be very cautious not to over do it.

After 2 ~30 min sessions I'd say I'm probably 2/3-3/4 to completely eliminating the grooves (they appear to be gone after filing, but still reveal themselves from the fuzz upon playing), but the difference in volume is already substantial. The note hardly sounds different from its neighbors now, even though its still not fully striking the third string. Given that the objectionable volume difference is more or less gone, I'm tempted to leave it where it is, and just let the remainder rebalanced from playing over time rather than removing any more material. Does that make sense?

Thanks again for everyone's comments and guidance, it made a huge difference just in time for our first party at which the piano got a great workout smile

I'll post a picture of the progress when I can post from home.

Rob
Posted by: miscrms

Re: Soft Volume After Replacing Missing String? - 02/27/13 01:44 PM

Here are the pictures at long last.

The before, I tried to get the light coming in from the side so the shadow helped show the deeper groove on the left side. You can also see it looks like the damper has been twisted a bit from just striking the one string for so long. Am I right in thinking that loosening the screw on the back of the damper block would allow me to rotate it on the wire to turn it back straight?



And here's the after view from the top.



And finally the side profile view after filing.



Eventually all the hammers will need to be filed down to even out and so they can be centered on the strings, and the dampers need a lot of work, but this made a big improvement in the playability for now.

Thanks again to all who contributed.

Rob
Posted by: Eric Gloo

Re: Soft Volume After Replacing Missing String? - 02/27/13 03:00 PM

Originally Posted By: miscrms
Am I right in thinking that loosening the screw on the back of the damper block would allow me to rotate it on the wire to turn it back straight?


Yes...BUT...be careful! You'll want to support the damper block on the sides, so as not to add sideways pressure...both when loosening and tightening the screw. For damper adjustments, I have long-handled tweezers to hold the damper block in place. You don't want to stress the 139-year-old pieces of wood. It is possible to crack the damper block, just by trying to unscrew the adjustment screw, so be careful of that, too.

If the damper felt is worn unevenly, it may not dampen properly if you straighten it out. Does it dampen all 3 strings sufficiently the way it is? If it seems to be working OK, sometimes it's best to leave it alone.