Point one on the
checklist was tightening all of the screws. Now if all of the foreign material was
cleaned out from under the flanges, usually by using compressed air, we are now
ready to travel the hammers. What we are looking for is a hammer that swings to
one side as it is raised from the rest position to normal striking height.
I find it best to use a
long rod such as an old pedal rod in traveling a whole section of hammers at one
time. Insert the rod under the hammershanks near the hammer, at about the rest
felt/rest rail area. Hopefully the rod is long enough so the ends will protrude
over into the next section of hammers. If not, make sure the rod rests on at least
one shank at each end so as to be level.
If any hammers are
badly angled (Point 17), I find it easier to correct these first before
traveling. On the other hand, if the hammers are traveling way out of
alignment, then it might be easier to travel first, angle later. Anyway, keep
in mind that a travelled hammer must be angled in order to keep the striking
surface square to the string, assuming that the striking surface was square in
the first place.
To find hammers that
need traveling, lift the rod up and down approximating the hammer-to to string distance
and watch for hammers moving towards their neighbours. All hammers should lift
vertically, with no sign of movement to the right or left. If necessary, use a
square or a board with vertical lines drawn on it as a guide to make sure the
hammers all lift perfectly straight. Without the use of a guide it is possible
to travel all of the hammers, but end up with them all moving slightly to the
right or left. Any horizontal movement will result in a loss of power, abnormal
wear on the hammer and its bushing, and voicing problems. Do not bother to travel
the hammers any higher than a few inches, since they do not function any higher
in the piano.
Any shanks which are
moving to the right or left are corrected by placing a thin shim under the flange
so the shank will travel vertically. The rule is to place the shim on the side
of the flange toward which the hammer is traveling. In other words, if the
hammer is moving to the right, place a shim under the right side of the flange.
I prefer to take the flange off completely and place a gummed piece of paper
such as packing tape or a strip of masking tape as a shim. This works better than
just a piece of newspaper so often seen here, since they stay with the flange
whenever it is removed in the future.
Also, in taking the
flange off to shim it, I always check it to see if some foreign material is
causing the hammer not to travel correctly. If more than two shims are necessary,
filing the flange on the opposite side is preferred to installing many shims. In
really bad cases, rebush the centre.
Since shimming the
flange actually tilted the hammer, now we need to go back and correct the hammer
angle. In case you do not know what I mean by hammer angle, it is correcting
those hammers which are leaning to the right or left. Do not confuse this with
the angles which the hammers are glued on to so that they are aligned to the
string angles. This is in a different plane. The angles we are talking about
are caused by the shank warping or by shimming the flange to correctly travel
the hammer. To correct the hammer angle, take a heat gun or an alcohol lamp and
heat the shank by quickly passing the heat up and down the length of the shank.
At the same time, apply
a tilting pressure to the hammer head in the direction it needs to go to
correct the angle. You will feel the shank twisting when it gets hot enough.
Don’t burn the shank! Keep in mind that some pianos are designed for the
hammers to be slightly angled a couple of degrees in certain sections, usually the
tenor or bass. Note that if the same rod is used here in angling that was used
in traveling, the hammers will all be uniform in height (remember that we have not
got to regulation yet) and therefore easier to spot those which are misangled.
Do not lightly pass over these two procedures, as they really make a difference
when it comes time to voice the piano.
Next on the checklist
is Point 18, reshaping the hammers. At some time in the future, we will discuss
when to tell if the hammer has enough life left in it to reshape it or if it
needs to be replaced. As this post is based mostly on reshaping in the shop, we
will also discuss in the future how to reshape in the home. Remember that a
well-shaped hammer not only sounds better, eliminates a lot of needless voicing
and wears longer, but also makes more money and a better reputation for you.
Note that after traveling and angling, the hammerstriking surface must always
be filled to square it to the string.
Regraphiting the jack
top and balancier window is Point 19 on the checklist. The easiest way to do
this is to brush on Dag 154. Keep in mind what we are doing here. Generally
speaking, the less friction there is between the moving parts of the-action,
the better it works. Recently for this reason, many pianos manufactured today use
teflon (often coloured blue or green) at such friction places as the top of the
jack and balancier. Teflon as used here is definitely superior to graphite. The
knuckle never gets coated with teflon which has rubbed off like the graphite
does. A knuckle should be clean and smooth to function at its best. If dirty
with graphite, clean it! For this reason, after applying the Dag 154, take an
old treble hammer and rub these surfaces, or burnish as it is correctly called.
This helps in making the surfaces even slicker by polishing and takes off any
excess graphite which otherwise would have worn off onto the knuckle.
Point 20 is spacing the
jack in the balancier window. Remember to check and make sure the jack works
freely after spacing it. Do not space Steinway teflon bushing jacks in this
manner. Hammering on a teflon bushing will ruin it. Remove the centre pin and
put a slight bend in it, then reinstall the centre pin.
Next, we go on to
repairing the knuckles, Point 21. Good quality knuckles have been hard to find. Manufacturers have been able to get a better
quality buckskin. But only in the past couple of decades have really high quality
knuckles become available.
As a technician, you
have to decide whether to use the old knuckles which the piano has or to
install new ones. If the knuckles are of good quality and are just a little
worn and slightly out of round, then it is acceptable to restore them.
If the knuckles are of
poor quality (some of late are not even buckskin but rather cowhide), or if they
are very grooved or flat, replace them. For the benefit of those technicians who
work on Steinways, felt bushing shanks and flanges have now become available
which are of the finest quality. Slightly flattened knuckles can easily be made
round again. Purchase some good quality wool yarn (not synthetic) and a large needle
with an eye large enough to hold a strand of yarn. Pass the needle with a few
strands of yarn into the knuckle, at the point where the knuckle rests on the
balancier. The new yarn goes between the leather and the knuckle core. The fibers
of the yarn will intertwine with the core and become permanent. Cut off any
excess yarn from the sides of the knuckle and you are in business. As a final check,
squeeze the buckskin of the knuckle and look for any slack. The leather should
be nice and firm, with no visible play.
If the knuckle is a
little grooved, I like to file this groove away and make the surface smooth
again. In later regulation, the whippen will have to be aligned to the knuckle.
If this groove exists, any alignment of the whippen will result in the jack
hitting upon a new part of the knuckle. The jack height will then vary as the
jack makes a new groove, and repetition problems will result, if it no longer
has the tolerance it needs.
Sometimes we find a
hard knuckle. Usually this is from glue getting on the leather when the knuckle
was made. The buckskin should only be glued at the very ends the working part
being free against the core to flex. To eliminate a noisy knuckle, prick the
leather with your voicing tool. If this does not work, replace the knuckle. When
replacement is in order, be sure to glue it in proper alignment. Nowadays,
knuckles are often seen which vary in their alignment. The core should be at a
90” angle to the shank, but I have seen many where the rosewood was so far bent
out of shape that the knuckles were 1/16” off from the neighbouring knuckles!
Combine this with cowhide being used instead of buckskin and you have a piano
that not only plays unevenly, but cannot repeat since the jack hangs up on the
rough fibres of the cowhide. The only remedy here is to replace the knuckles with
ones which have good buckskin and to properly align them. The same goes for the
felt knuckles which Steinway used for a while. Next week, we will
continue with Point 22.
No comments:
Post a Comment