Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Basic (but hopefully not unintelligent) hammer questions

I'm just starting out, so any advice will be much appreciated.

The instructions that I've read on shaping hammers all say to make sure that an even amount of felt is removed from the top and bottom. But what should be done when the hammer felt isn't symmetrical to begin with? Both the inner and outer felt are thicker on the top half of many hammers of the Baldwin acrosonic console that I'm working on. Is it possible that they were like that when new? The piano is 35 years old and moderately used; the hammers have never been filed. Making the hammers symmetrical now would seem to require taking off a lot of felt.

I've also read that when hammers are realigned to the strings, the strings will find their old grooves again, putting strain on the flange. At the same time, I understand that I should remove as little felt as possible at the striking point. How do you balance wanting to align the hammers to the strings and wanting to be conservative about taking felt off the striking point?

I'm also noticing with the action out of the piano that several hammers get stuck on the top of the damper felt on their way back. When the action was in the piano, all of the keys worked and I didn't notice any not returning to the rail. Is this an artifact of the action being out of the piano, or should I do something now to fix it?

I've been reading as much as I can, but of course it's being confronted with an actual project that brings up questions like these. This is the piano that I grew up playing, so I'm not subjecting anyone else to my learning curve. I have a couple of pictures, but don't know where to post them so they can be seen.

The best advice I can give you is to order this: http://www.thevoiceofthepiano.com/index.shtml

Without the strings to stop them, the hammers are going further forward than they would in the piano.

That looks great, and I don't remember running across it in any of the books lists that I've seen. It amazes me that more piano tech books don't come with audio/video

Karen

I had the same problem recently, how to reshape hammers without knowing how to do it, or the experience to avoid damaging them - a big risk!

My solution was to manipulate the hammers back into shape. While doing this I discovered by chance that White Wizard or a similar surfactant makes it much easier to do this. You just apply some round the strike point and the shoulders and gently roll from the shoulder towards the strike point once the felt has softened.

I did this last night on a bass hammer and in couple of minutes the grooves were gone. This morning it had dried out and D2 was playing more powerfully and sustaining longer than before.

My "don't dry the poodle in the microwave disclaimer" is that I don't know what long term effect if any this has on the felt. On the other hand there is no need to remove any felt and you could still file the hammers later on.

I wrote about this at some length in another post Massaging hammers back into shape without filing.

It will all depend on the state of your hammers of course, and whether they have been hardened with lacquer - mine weren't.

If you'd like to post some pictures you could upload them to a site like kiwi6 and then put the link it gives you into the image dialog on this forum.

Good luck

Ian

Palm to forehead. Of course. Thanks for pointing that out. I checked it out and you're exactly right. I guess I could wonder why some hammers have less clearance than others but suppose I shouldn't worry about it.

Ian,

I read that thread and your solution is very interesting. Since my doing anything with a piano is already an experiment, I thought I'd stick with the conventional approaches first. But I'll keep the massaging technique in mind as I gain more experience.

Karen,

Why not post the pictures of your hammers so everyone can see the grooves and how flat the strike points are and advise?

Before you start filing I'd suggest you look at this thread on the clavio forum. Look at the before and after hammers lined up on page 2 and see how much felt has been removed, and then at page 3 at the photo showing more felt gone to make a sharper strike point, the one marked "So?"

To avoid that sort of calamity, if you want to experiment with massage at all, I'd respectfully suggest you try it on one or two hammers first (with or without White Wizard, or a damp cloth as one reply suggested). You will still be able to file them if you wish. Once you have filed away the compacted felt at the ends of the grooves it will be too late to massage them back into shape.

Ian

I came across a few sets of asymetrical hammers with Baldwins in the '70's. Curious thing is, some of them sounded better than those pianos with symetrical hammers. On the few occasions when a light resurfacing was necessary I found it prudent to follow the given shape than try to 'correct' them by shaping since this would leave the hammers with incomplete layers of felt. If their shape bothers you, prepare for your first hammer hanging job and put new ones on. In the meantime use the current hammers to gain experience.
Start at the lowest note and shape half of the bass hammers. The lowest hammers don't need much felt removing so you will be gaining skills and experience as you progress. Then start at the top note and shape the hi treble hammers. They, too, will usually not require much felt removing. Don't remove too much felt in one go. Better to do a little at a time and go over the set of hammers a few times. fit the hammers to the strings in these extreme sections so that you will realize the necessity to keep the sandpaper paddle square to the nose of the hammer. I use a double width paddle so that I can keep square by doing two hammers at the same time where the hammers are square to each other.) you can see, hear and feel the felt layers coming off. If you find you can also taste and smell the felt coming off, use a face mask. By the time you get to the middle hammers you will have gained the experience to do a respectable job on them. I have not gone into detail but doing the hammer to string fitting in the same operation as removing the last traces of the string marks will ensure you don't remove too much felt. You will have to do some string leveling as you go where you find it necessary

Rxd,

Your post is making me realize that there are more variables involved than I thought.

I'm replacing all of the corfam with buckskin, so I took every other hammer out of the action and planned to shape the hammers individually. I'm now wondering which is preferable - individually vs reassembled and out of the piano vs in. I thought that I could give the hammers more support and get a better view while I had them out.

The piano has never been regulated, so I don't think that the hammers are necessarily square to each other. I thought that hammer shaping comes before regulating but would it be better to align them first?

I'm trying to be conservative about removing felt especially at the strike point and on the 5 that I've done, there are still string marks there. I've mostly just reduced the depth of the grooves. There are some in which one of the strings was contacting the hammer at its edge, and I'm still not sure what I should do with these - remove enough felt to make it completely smooth or continue its misalignment. The hammers in general aren't too far gone and replacing them isn't an option.

Your advice about symmetrical hammers makes complete sense. For hammer shaping, I've read only Reblitz; for regulating, I'll be using Bill Spurlock's PACE instructions. And, of the course, this forum. Thanks.

All

I thought this might be a good opportunity for setting out some reasons why massaging hammers into shape seems to be a better technique for amateurs than filing.

Filing and needling are techniques for professionals. They require experience and produce consistent predictable results. So, for example, concert piano hammers are filed regularly and replaced when necessary.

Some professionals have advocated steaming hammers in heavily used practice pianos between filings. The idea is to prolong their life and presumably reduce overall costs.

Most owners do not fall into either of these categories and will only have their pianos tuned regularly. Many will wait years or decades for an overhaul. This means their instruments will be performing acceptably - but below par - for most of their life.

If you have a fine piano the answer is to make better use of the services of a good piano technician, otherwise the answer may be to learn how to do basic cleaning and regulation yourself. This can be quite straightforward until you try to answer the question, "What to do about the hammers?".

The fundamental problems are the felt at the strike points is compacted, strike points become flat (i.e. there are elongated grooves) and the felt hardens with age.

Apart from its risks, which can be avoided with care, filing removes felt which affects the operation of the piano as Reblitz explains. Rather than softening the hammer, it also exposes harder felt increasing the need for needling. Filing does nothing to reduce compacting at the strike points.

Massage, on the other hand, restores the hammer to near its original shape and can reduce the compacting of the felt at the strike point as well as softening it round the shoulders.

A modicum of filing may still be advisable after massage: (a) when the surface of the hammer is damaged at the strike point and (b) to ensure the strike points are flat and level with the strings.

Restoring the rounded shape of the hammers will go a long way to reviving the tonal qualities of the piano. There should be no need to needle all the hammers although "fine toning" of some may be beneficial. Furthermore massage will only have a minimal effect on regulation.

The main drawback is the time massage takes, but using surfactants reduces it to a minimum. Professionals do not have time and must employ proven methods. Some owners can make time available - a few hammers at once perhaps.

Just my thoughts - they worked on my $100 1925 piano.


Ian

I worry about using a surfactant, which if I understand correctly is a cleaner. A video demonstrating the effect might be useful, or at least let us see how much you are using and your methods.

Jake

Yes, I share your concerns. The top edge of one hammer had a grubby black mark so I used some White Wizard as a dry cleaner. I was surprised to find this made the felt very soft but it also became very easy to manipulate. Once it had dried out, the felt seemed to return to normal.

When you look into it, you find that surfactants affect the surface properties of the wool fibres. This is actually what you want, in the sense that you want move the fibres back to where they were.

In other words the repeated impacts of the strings on the hammers cause some of the fibres to migrate towards the shoulders, thus creating ridges at the end of the grooves, and you want to push them back again. It is quite hard work to do this without the surfactant and very easy with it. An advantage of the surfactant is that the grooves readily disappear.

On balance, despite the reservations you imply, I've decided to use surfactants on the remaining few hammers. The first hammer and a few others have shown no detrimental effects and the tone and sustain are as good if not better than the others I've treated.

I apply a rather small amount of White Wizard on a toothbrush round the edge from shoulder to shoulder over the strike point. This gives you a few minutes to massage the hammer then it dries out in an hour or two (I leave it overnight). The stuff turns to dust but I do not know how much remains on the surface of the fibres or what its long term effects might be.

For the method see the links in my first posting above. I'll do a video or some before and after shots when I work on the remaining hammers.

Ian

Here's a picture of an asymmetrical hammer (first time embedding a picture - hope it works):

[img:left]https://picasaweb.google.com/108316672733534722980/2011#5610127626332514066[/img]

The axis of the felt is different from the axis of the wooden molding - I have to draw the lines to stay focused on the strike point. After filing, the curve coming off the strike point is rounder (more gradual) on one side than the other, but this seems unavoidable.

I bit the bullet and filed them individually with 150 alum. oxide paper on a single paddle until the grooves were almost entirely gone. I had already taken them off the action to replace the Corfam with buckskin, and being able to hold them seemed to make it easier to file them from all sides equally. I've done half the piano (took out every other hammer) and will now replace them and do the other half. When they're all back in the action, I'll do the final sanding with 220 and 400+ sandpaper in blocks of 4 or 5. The deepest grooves that I've measured so far have been about 1/16". If anyone thinks I've done anything reparably wrong (or irreparably, for that matter), feel free to let me know.

I now have a couple more questions about hammers:

Wobbly hammers - The original, mustard-colored glue holding the hammer head to its shank has a hairline crack where the hammer wobbles. Can I just add hide glue to the cracked original glue, or do I need to remove the hammer from its shank and reglue it? Can anyone tell me how I'd go about the latter? I don't have specialized heating equipment other than a slender soldering rod.

Hammer rail felt - Would it be wrong to replace 3/4" rail felt with 1" wide? Schaff's only size narrower is 5/8". The original felt's been compacted by the shanks and I'd like to eliminate one more factor that's contributing to increased hammer distance from the strings. Does anyone have any tips for keeping the hammers out of the way when replacing the rail felt?

Thanks to all for your suggestions - they're really helpful.

You probably already have the tool you need to soften the glue on the hammer. It is an electrically heated hairdressing tool that is far bigger than you need for this job but I am told that it clips on to a hammer and softens the glue. You can often simply pull a clicking hammer off it's shank without danger of damaging the pinning.
It is a good idea to centre each hammer on it's strings so that with any subsequent movement, the hammer still stand a chance of hitting all of its strings. Keeping equal Hammer spacing on these instruments is something of a trick since the hammers were not travelled in the factory. You might want to travel the worst offenders at least .... A fiddly job when the piano is fully assembled but not impossible. Strings can be moved to accomodate but then dampers will need to be adjusted and here I go again. To do one simple job properly takes a knowledge of the whole gestalt of the piano.
Also the hammer spacing tends to bunch up a bit on these instruments towards the treble end of the middle section .... It's weird details like this that make someone a Baldwin expert. I must have serviced and prepped hundreds of these when I worked for a very successful Baldwin dealer in the days when your piano was made. Your photo of a hammer brings it all flooding back. Your hammer was par for the course. Many were far worse. I'm not knocking Baldwin, most manufacturers were like this. Baldwins could always be made into musical instruments.

rXd, two questions:

Just to be sure what you mean by "hairdesser's tool" - are you talking about a hair straightening iron?

And (sorry to Karen for the semi-off-topic) would you have any similar tips for removing hammers that have been glued in using white (PVA) glue? I'm not sure how soft this glue becomes under heat.

Mark:

I use a hand held steam cleaner to soften glue joints. Wife found one at a yard sale. She's a pack rat. No that's not right. Pack rats leave something in exchange. She just keeps collecting!

rxd -

Funny, I can't tell you how many years it's been since I owned a single electric hairdressing tool. Mitre saw? Grinder? Welding gloves? No problem. But a curling iron or a hair dryer? I'd have to make a special purchase, and no IRS agent would believe it's job-related. How about a magnifying glass under the sun?

Would it be helpful to note the most uncentered hammers before filing them? Is there a way to center them on the strings when they're outside the piano?

I'm also curious - when I need to file some hammers more than others, they'll be at different distances from the strings. Presumably after the piano is regulated, they'll all be at the same distance. What part of the regulation absorbs the difference the most? I mean, what instead becomes most inconsistent from key to key so that the hammer distance can be consistent?

Thanks to all for your comments.

rxd - sympathies if you had to do more than one set of corfam replacements. That is tedious! (though satisfying in the end).

Mark,

I'd like to go a little off-topic too, but am trying to be disciplined about it! Feel free, though.