Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum wrong hammer replacement

I had 5 years ago on my upright a hammer replacement, abel brand, smaller size than original.
It was obvious at first sight, no need to be a technician, but i didn't say a word.After all, is not my job.
When an other technician did the regulation, he shows me that the hammer of course didn't strike the strings in perpendicular line.
So he did what he could, mostly raising the action by lifting the support bolts, striking keys in upper octaves looking for best sounding impact point.
Now after some filing in the past hammers had become grooved and blunt but in a slightly diagonal way since it strikes in that direction (repeat, very slightly diagonal way).

now : how can i know which is the original hammers size?how can i discover the right impact point on the string?
i think that filing the hammers again to shape them and eliminate grooves would only make thing worst.

Your thoughts would be really appreciated

in case of misunderstanding.....
the wrong size hammers have been by a technician (?), not by me....

Can you write to the manufacturer, or is the piano elderly?

By wrong size hammers, do you mean the length from the tip to the bore, or the weight or thickness of the hammers? The latter is difficult to match, and will mostly affect the sound of the piano.

Treble hammers should be perpendicular to plane of the strings. Bass, and perhaps some tenor hammers need to be twisted slightly so that they clear their neighbors. Hammer shanks can be twisted with heat and moisture. Dampen the shank, heat it with a clothes iron until the water has evaporated, and then gently twist in the proper direction. Hold it until it cools.

If the height of the hammers is uneven, that is difficult to fix.

Bellspiano,

it is barock dx 800, also known as gershwin in usa, manufacturd in hamamatsu japan, end of production 1984

Bdb,

for sure is a matter of lenght from the tip to the bore.They are shorter, smaller, As concerns the weight and the thickness i couldn't say.
Now i have to order a new set of hammers and i can't afford any mistake, most of all to look for a good technician

but i remember that the sound actually changed, a loss of power so to speak, and the tone less bright, so probably is a matter of weight too, i guess.

He may have messed up the strike point.

Pwg

sure he did!

how can i detect the right strike point?

P.s. Mr. Grey, i tuned temperament today with your sequence, it works great!

Glad you like it. I have been using it for over twenty years. Does not work on a really badly scaled piano (but then hardly anything works on those anyway).


On the strike point:

1) Remove the action

2) On note 88 make a mark straight across the strings 2mm down from the top.

3) Mark the center of the hammer moulding on the side right up to the strike

4) Do the same to hammer on note 72 and mark the strings at 11/32"

Lost my edit time.

4) or 8.75mm on note 72

5) These are starting points for strike line.

6) See how close the center of the hammer lines up with these points. If they are right on the money you are in pretty good shape. If not, then your strike point is probably compromised. It is usually determined tonally at these notes (or close by). You need a pretty hard hammer at 88 to really hear it. Slightly above or below, but it will not be far from these.

Tell us what you find. Then we can go from there.

Pwg

ok!i'll let you know. thanks you all!!

If I were doing this, and the hammers were not worn, I would cut off the hammer shanks and rebore the hammers and the butts. But you may not have the equipment for doing that.

Once they were rebored, I would cut shanks to the proper length, glue the hammers to them, and then glue them into the butts. That way you ensure an even height.

The bore distance is determined by establishing the rest point of the hammer and the distance to the string, and how far the hammer moves to let-off. You need to do that in the bass and treble separately, but the distance in the bass should be the distance between the plane of the bass strings to the plane of the treble strings.

I think 2 mm is too close to the top end of the speaking length. You can experiment to find the proper strike point, but that is kind of difficult. About 6 mm is where I would start.

Bdb,
in the factory where i practice, they have all the necessary equipment.Hope to have the skill, too,Luckily meanwhile there are no good ear tuners, they are accustomed with these kind of works, they replace hammers everyday.
Apart from the smaller size/weight/thickness the hammers are worn,so i'll use a new set.
Let's see what i'm able to do, thans for the advice

6mm is way too wide for note 88.

Pwg

Well, the piano will not explode if you try 6 mm. I have heard a lot of weak top notes where the strike point is too close to the end of the string, which are improved by moving it farther away.

If you are going to experiment with optimal hammer strike point then 6mm is a reasonable starting point from which to judge improvements as you reduce it.

Scanderbeg,

At the factory where you work, is there an action "expert" you could consult on the matter? Maybe have him/her look at it?

Just thinking.

Pwg

yes there are several "experts" that either replace new hammers and file old ones.

but, looking the way they shape the hammers ( sometimes they don't match the strings),i don't i much i can trust them....
hope they do not such a good work just because they are always in a hurry.
first times i was trying to close a clean unison i was going crazy i didn't know hammers fitting the string are essential to achieve it
anyway it was my intention to ask for their opinion (even if when i ask them about inharmonicity they thought i was talking about quantic physic,Not kidding)
i'll let you know.