Dear technicians,

This weekend I re-shaped the hammers on an upright that's in my wife's teaching studio at a kindergarten. They don't have a budget for piano maintenance, so I've offered my services, and have already done a pitch raise. It's a "well-worn" instrument that was pretty much used up and then donated by a performing / recording artist. The sound was extremely tinny, especially on the mostly used notes (mid range, closer keys). You may recall that I showed some pictures in the past, and the general opinion here was that these hammers were basically on the verge of need for replacement - which is not viable in this instrument.

Tonally, there really wasn't much to lose, so I tried my hand at re-shaping. I would welcome any feedback, comments, constructive criticism.

I worked by hand only (although I have a Dremel tool with sanding drums) and did the rough shaping with 80 grit paper, then the finer shaping with 320 grit, and because the felt was still rather "lumpy", polished with 600 grit.

While the bottom shoulders of the hammers sanded nicely, the top shoulders were very brittle and came off in lumps - presumably previous technicians had needled only the top shoulders? I found some deep holes and even a broken-off, rusted needle...

There has been some tonal improvement, but not even remotely what I'd hoped for. The heavily used notes are still very bright and loud. They obviously have very hard, compacted felt, and some needling is called for.

I've made an album (21 pictures) on Picasa:
Click here.

Here are some examples:

Hammers on the left are as I found them, those on the right were even worse (felt coming off the flattened striking point in tufts) and are already partially re-shaped:




Some examples after re-shaping:




As I said, any comments welcome, especially critique, but please keep it constructive. I'm on a learning curve.

[Edit additional comment]

In case you're wondering how long this took, I'm a slow and conservative worker. I
... tightened all flange and rail screws,
... shaped the hammers,
... cleaned the action thoroughly,
... re-glued the lower felt of a hammer that had come loose from the molding, and
... re-positioned the jack slap and let-off rails for easier access to let-off screws.
All in all, the work took me about 9 hours.

What glue are you using to glue the lower felt? I am a learner too.

Mark

They certainly look good. As they have already been well needled, at least on top, I wonder if an alternative method of softening them might be better. Various methods have been discussed in this forum; the one that springs to mind was Del soaking the hammers from a Kawai (from memory). You could try out a few hammers with different methods, but of course it's a good opportunity to develop needling technique.

Weiyan:

I used cyano-acrylate glue (superglue). It is one of several possibilities that have been mentioned here. I'm not sure what adhesive the factory used originally, but the residue on the wood and felt looked white. So I didn't want to use hot hide glue, because I would have had to clean the felt and wood first. I didn't want to disturb the felt any more than necessary. One advantage of superglue is that it adheres to most materials. I will check the hammer after a few months. The original glue joint failed because the wire staple failed. It was bent instead of penetrating the wood. The glue on several other hammers is starting to come loose, but the staples are holding them together.

Ian:

Thanks for the compliment. Yes, I've been wondering about alternative softening methods. I doubt whether they've been treated chemically, because the lesser-played ones sound quite good. The problem hammers are mechanically compacted more than anything else. So a chemical soaking or leeching is not my first choice. I'm considering a combination of needling and mild steaming, and/or moistening with a spray of alcohol/water (as shown in Ron's video, only a bit more intrusive). Hey, I might even give your "toilet roll technique" a try - although I'm worried about the glue joints in the heads. Are your rolled hammers still holding their voice?

Mark :

From the photos, it looks as though you've done a very nice good job. I've seen some really bad examples of hammer re-facing undertaken by professionals, so congratulations on a job well done.

The tone will be even brighter after re-facing, now that the striking surfaces are free from cuts. Rather than applying anything to the felt, I would re-voice them using needles. If you feel brave enough .... and needle through the shoulder of the hammers (underneath the strike line) not on the strike line. The idea is to get some softness into the layer of felt under the strike line, not to damage the fibers on the hammer noses.

Voicing takes a great deal of skill and patience, and not normally something to be undertaken by non-professionals ... but in these circumstances you can't really do much but improve things if you keep away from the strike line.

Johnkie,

Thanks for the compliment. I didn't realise that the tone would be as bright, or even brighter, after reshaping. I had somehow assumed that the rounded strike point (i.e. smaller contact zone with strings) would result in a mellower tone - and hence was quite disappointed... But that's the nature of wrong assumptions.

I could really do with a hands-on mentor for voicing. I have found a professional technician who is prepared to guide and evaluate me in various aspects of piano work, but unfortunately, he has said himself that he is not an experienced voicer. On the other hand, I need the practice. I read lots about reshaping before doing this job, and I've read as much as I could about voicing (short of buying André Oorebeek's highly regarded albeit rather pricy book "The Voice Of The Piano").

The piano is really piercingly shrill in mid-range. Two minutes of Well-Tempered Clavier rang my tinnitus right back into action. Ouch!

So methinks I'll give it a go.

Yes. This looks like a good job
but don't put your finest shaping stick away yet
Hard to tell from the photos but it is important that the strike face is 90 degrees to the side of the hammer so that it stands a chance of hitting all 3 strings at the same instant.

Is the tone bright, thin and sizzly or Is it bright, full and solid?
You will most likely find some of both.

Go through and fit the hammers to the strings either by leveling strings or subtly adjusting the strike face of the hammer. Or some of both.

Do this before even considering any needling. It will reduce the ammount of needling when you do get round to it. It results in better sound and is very time effective.
If you go the chemical route, do it after the chemicals are thoroughly dry.

Remember not to touch any piano strings with bare flesh. It stains them a few days later. Not good on a new piano. Excessive touching will make strings go dead.

Mark,

Yes the hammers are doing well; I need to have another go at middle C, one of the first I did, to remove the last vestiges of hardened shoulders.

Johnkie's point about hammers being brighter after re-facing was slightly surprising until I remembered the felt at the strike point is as hard as ever it was. So you have to soften them by needling, tried and tested, or some other means. If the felt is actually compacted, as distinct from being worn away to reveal a harder layer, other methods can be considered. However needling will work in both cases and I do not question Johnkie's professional advice in any way.

Needling, as it were, introduces some shock absorbers into the felt but, as Johnkie mentions, some fibres get damaged. The alternative is to break some of the bonds between the wool fibres which, as I understand it, are scaly. The scales lock togther to make the felt hard. Water on its own or, more so, water and surfactants "lubricate" the scales so the fibres can slide over each other more readily. No doubt you can explain these things far better than me.

What I would try on a couple of hammers is manipulating them gently after wetting with (a) water (damp cloth) and (b) surfactant (I used White Wizard dry cleaner) and, after they had dried out, see how the effects compare with needling.

Finishing with 120 grit may help. More of a diamond shape might help, too. But it is tough to do with the hammer in the action - and there is not much at the strike point to work with. There really should have been a dramatic difference, hmmm.

I had good results with steaming and side needling to "detinnify"
old timers.

Kees

Why do the hammers look wider in some places than in others? Is that because compression on the strike point has caused them to widen? If so, is this not visible in the pre shaped hammers because the old felt is covering up our view of the thick spots?

Lots of European hammer sets are shaped in this way because of the angle to allow each bass hammer to pass by the next one. Photo 9 of the photo album shows the same hammers pre-shape.

Mark;

Just had a quick look through the photo album. The hammer set looks to have enough material to work with; in the mid treble the material is a little shy but you should be able to voice them out without emptying the hammer set completely.
For reference if you recall we were chatting about this on my blog posting March 5 2011 about voicing. You had some questions there regarding the photo album of André Oorebeek seminar here.

blog posting

The hammer shaping looks real good, Mark.

The key is to take your time and not get in a hurry. Also, make sure your sand paper is not worn out... (ask me how I know this ).

Dan Silverwood is a great piano tech cyber-mentor too! Ask me how I know this...

Rick

Jeff:

I was wondering whether 600 grit might have "over-polished" the surfaces. I'll keep that in mind.

Doel:

If you don't mind, I'd appreciate a short description of your techniques. How much steam, how long? (Say, in comparison with Ron Koval's video) And you needle at which position(s) into the side? I know that discussing these things on the forum can be a contentious matter, so PM me if you prefer that.

Dan:

Thanks for answering Ben's question on the shape of the bass hammers. By the way, I found it quite challenging to keep my sanding paddle perpendicular, because on the lower half of the hammer, the right side is sliced skew, while on the top half, it's the left side. The eye must only use the uncut side of the hammer side as a reference, and ignore the cut side.

Yes, I remember our Q&A on your photo album of the seminar. Very useful - thanks again. As you say, in this piano the area around the treble break doesn't have much material left - I hope it'll work. The worst sound is actually in the fourth octave, leading up to the treble break, and there is still some material left there.

Rick:

Much obliged. I agree, abrasive is just like food: best used fresh. And yes, this job is not one to rush. Fortunately, I've been blessed with above-average patience (especially when it comes to mechanical jobs such as this).

One more thing I forgot:

Both my wife and I noticed that there has been a noticeable improvement in the bass, around the second octave (where I didn't really expect it, because those hammers weren't all that deeply grooved. This area of the piano has returned to a much more pleasant "mellow-yet-clear" sound - not equally on all notes, but noticeable nevertheless. The mid-range and treble, in contrast, are unpleasant as ever.

Mark

Did you pick up the suggestion on Clavio to "loosen" the compacted fibres under the old grooves by needling/scratching? Those fibres could merit special attention as they are the ones that hit the string.

Ian,

Yes, I did pick that up. But judging by the percussive, shrill and frankly loud tone, I suspect that there is hardly any cushion left in these hammers. From what I've read, softening the strike point at this stage, without seeing to a proper cushion in the shoulders first, would be akin to putting a gauze pad on a granite ball and expecting it to bounce.

Mark

Yes, I know, but you don't want to leave a granite layer on the cushion at the strike point either! Michael has mentioned it several times so he must think it's important.

Just a point.

Mark, here the details: Read Keith Atkins "voicing for the rest of us", then read/watch Andre Oorebeek's book/DVD, then look up threads on steaming on this forum.

In the end I steamed each hammer about 2 seconds, made 2 passes like that. After steaming my hand I decided to wear gloves.

For the side needling I started subtly following Atkin's suggestions, with little (but nonzero) effect. In the end I ended up needling wherever I could in a cloud of stabs, randomly placed away from the strike point, more deliberate near ito .

The piano's (2) I've tried this on improved from "unplayable" to "playable". In both cases hammer filing was impossible as there was not enough felt left.

Kees

As a result of this tip Keith kindly sent me a pdf copy of "Voicing for the rest of us".

Mark, I imagine you have a copy. The rationale for side needling and methods are very clearly set out. I had not realised how easy it is do; Kees' frenzied attack on the hammers in the previous post notwithstanding.

Keith's prescription for dealing with the hard shoulders that form at the end of the grooves rang a bell with me. Dealing with them made the biggest difference of all to the tone of the Schiedmayer.

With hammers that are rock solid from the crown to the wood you obviously have deal with the hard core in between. I was interested to see Keith mentioned pliers as last resort as did J Cree Fischer in his 1907 book on Tuning I skimmed through the other day.

Until reading Keith's article I was extremely reluctant to needle anything, now I'll certainly have a go on the Ibach when I get round to it. The alternative is buy a new set of hammers!

I'd say that's a good first filing. It's probably a little too late to do serious deep-needle voicing in the shoulders because that will ruin your filing job. Next time, do that first (if the piano is unreasonably bright), and then file the hammers. As UprightTooner already mentioned, you might want to give the hammers more of an aggressive, diamond shape.

How do you know that an aggressive diamond shape will be better than a nice round shape? There will be less hammer mass and less shoulder support.

Well, it won't be if the voicing is crap. But, I was taught that it is desirable to keep the string/hammer contact area to a minimum. Some argue that modern hammers are too massive in the first place; if you're part of that camp, removing felt is not an issue. If you are, I'd say that the amount of wool being taken off is negligible, and if you're still worried about it, do a Stanwood strike weight.

Ian:

Yes, I have Keith's article. I've tried side needling some harsher notes in my Ibach according to his method, with very little noticeable effect.

986:

Thanks for the feedback. However, I'm not sure how one could needle before filing. I mean, how would one judge the effect of needling if the strike point of the hammer is flat, grooved, and 3/8" wide? With a totally knackered strike point, how could you hope to decide whether you've needled too little, correctly, or (heavens forbid) too much?

Hence I decided to restore a proper shape first. You yourself wrote that one should keep the contact area to a minimum.

So, could you explain how to voice properly, if the strike point is completely degraded?

I have, by the way, voiced a few of the worst hammers, and they did puff out somewhat, and had a slightly rougher surface after needling, but a quick, light once-over with 600 grit smoothed them out quite nicely. So I don't think the voicing would "ruin" the filing job.

Mark,

Without casting any aspersions on the condition of your Ibach hammers or your skills, don't let anyone run away with the idea that I think sticking a needle in a really hard hammer, whether at the side or in the shoulder, is going to make much difference.

As Kees, and others have found, some hammers need a lot of effort to make them resilient. Perhaps Keith might like to comment on what you can achieve during a tuning session and when it is advisable to go further.

If all the felt in the hammer has hardened don't you need a method of treating the whole hammer, or the whole of a problematic region such as the felt behind the crown? The question is how best to do that.

Mechanical methods, such as needles and pliers, are quick and convenient but no one would deny they can inflict some damage on the felt. Maybe wool technologists can suggest a better answer.

Mark,

600 grit is too fine if you think the piano is too bright. You should try going over lightly with some 120. 80 grit paper will mellow it way down but I wouldn't go that far right away. I think you did a fine job on those hammers though! I believe it was a good exercise for you to get a whole set to reshape. I assume you used a paddle and did each hammer individually, have you tried gang filing? It seems you have some good info on all this but I am suprised this method has not been mentioned. Now that you have done a whole set with a paddle you can graduate to doing several at a time with a full sheet of sandpaper. One advantage of this is that the strike points will be at 90 degrees without much effort. Also it is much faster, even if you just use it for the initial shaping and do a final shaping with a paddle.

The most drastic initial effect on your tone that is very easy would be to lightly go over what you have with a rougher grit.


Hope this helps,

Daniel

Yes. Gang filing is quicker and has more reliable and even results. The tech that taught me said that the techs of old wouldn't do it. Of course, dealing with seperate hammers for finer work is the only way to go.

This is a strange thread. It has become 2-3 people groping and stumbling around in the dark having a go at their own pianos, ignoring the few suggestions from the professionals here, prefering the written word of the instruction books. It is a living breathing example of the incompleteness of the instruction books and the need for individual mentors so I have merely observed with interest.

Suffice to say that, like any other work on a neglected piano, adjustments have to be made several times until the final adjustments are so small that they make no difference to the other adjustments already made elsewhere. Tone regulation is no different.

I know at least one of the books speaks of first hammer filing and second hammer filing. Isn't this a hint? The job pictured here looks good but it is only a start and represents only the tip of the iceberg. More lighter filing and shaping will have to be done in between other work. While it is good to make our own mistakes, too often mistaken impressions of the effect of some operattions can be gained that become hard to erradicate.

Many tonal problems are in the stringing and misguided attempts to cure them by manipulating the hammer results is ruined hammers.

If there is little resilience because the shoulders are too hard, why not remove some of the shoulders?

Perhaps I should have explained better. If you have a piano with very hard hammers, it may be necessary (depending on your tonal preferences) to deep-needle the hammers. This would involve taking a 3-needle voicing tool, with 10mm long #7 needles, and needling the high shoulders (up to, but not over, the string cuts) until the needles go in easily... you're not counting, you're going by feel. Doing this gives some resilience to an otherwise rock hard hammer. It will cause the hammers to puff out substantially, hence why you should do it before filing. On the pianos I've done this on, I've found that it is virtually impossible to overdo it... you will probably get tired, first. And, of course, filing the hammers will brighten it up again, some. You would then have to do fine voicing, as necessary, once the hammers are filed.


I should also add that some techs take issue with this technique; that it is not appropriate for every bright piano (possibly even this one), and that deciding when it is necessary is your own judgement call, and you do so at your own risk. Hope this helps.

+3.



rxd, the old middle-European technician who was always saying "Der hasta be a bedda vay!" may not have been your mentor but you certainly remembered his advice. Sometimes there is a better solution to a problem.

As one of the two people groping around in the dark, and no doubt the one responsible for making the thread strange, I'd like to switch on the light and have a look at the problem of Mark's hammers. He says they are too hard for his wife to use happily in her kindergarten.

Mark is clearly keen to have a go at needling. I cannot imagine any reason why Mark would not embrace rxd's, Johnkie's and other's advice in this thread.

On the other hand, before picking up needles, anyone would do well to heed every professional's advice about the risks: Johnkie, rxd and Beethoven986 in this thread; Del in others; Michael Szécsényi on Clavio; our tuner, "you can easily do more harm than good".

The solution to Mark's problem is to get all the wool fibres moving again; just as you might aim to do flexing stiff leather, card or other fibrous material. Three possible ways of softening are: mechanical (e.g. needles, pliers), chemical (e.g. soaking), chemical and mechanical (e.g. soaking and manipulation). They can all work to a degree and there may be others. Assessment and testing and should determine what's best. Needling seems to be the only general option when the hammers are staying in the piano.

On "instruction books" I must say they have been a great help, but I have succeeded thanks only to what everyone contributes to the forums, not least Mark who encouraged me to join this one. Seven specific areas where professional advice made all the difference come to mind immediately.

PS Anyone reading this post might also look at this thread on Voicing Techniques; notably, Patrick Wingren's first post in that thread about softening hard hammers before needling.