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32. Piano Action--  

Jack Loose
and Repair

We offer jacks, with or without flanges, for all types of pianos.
ALSO, jack spring repairs tools and springs for all pianos
AND, repair devices for broken jack regulation buttons.


If a jack is loose and its lower end is out of its mounting point in the whippen, you can replace it. If it is completely missing, chances are it is inside the action near the area where it used to be. Look from all angles and above to see if you can locate it. It also may have fallen all the way down into the bottom of the piano.

OK, Harry, jimmy the jack around until you have it about where it should sit. Now, get some very long pointed tweezers or a similar tool. You may use two screw drivers to do this, but it will test your patients. Grab the jack with the tweezers so that the back check and bridle strap wires (See diagram page) are within the jaws of the tweezers but not held by them. Work the jack into its depression in the whippen so that it is seated the same as the jacks nearby. This is a practice run.

Now, pull the jack back out and put a dab of Elmer's carpenter's glue into the recess in the whippen. Again grab the jack and work it into its mounting point in the whippen. Do not leave the jack to dry until you are absolutely sure the jack is positioned on the same level as the jacks on either side of it. If you leave it too high, or cocked at an angle off of the vertical, you will have made a real problem for yourself.

Be sure the jack spring is NOT in the jack while it dries. If it is, it will push the jack up out of its mount slightly which is bad news. Give the jack at least four hours to dry before you put the jack spring back in place, and then you can play it.

If the jack is higher or lower than it was originally, you will have to adjust the jack butt button (See diagram page) up of down to get the one eighth to one sixteenth inch clearance between the jack and the hammer butt when you have the key depressed. See Chapter Six, Section E, Jack the Slipper, and read carefully about adjusting the jack. You may also have to adjust the capstan on the back end of the key down yonder to get the hammer to sit at rest correctly.

Adjusting the Jack Motion

Be sure to read the instruction on Adjusting a Jack which is causing double blows.  If, after taking out the lost motion, your hammer still does weird things, you must next check the jacks.

Also, do you have a jack button screw broken,
or is a jack button completely gone?

My supplier has come out with a repair part which you can order if you do
break off the jack button regulating screw.  You can see in the graphic that
this device is easy to install with a provided wood screw.  
Do make a guide hole with an awl.  It is a genius little thing.



Grand Piano

Grand jacks do not come loose in this way, though the same thing can happen with the flange of the top lever (repetition lever) of a grand wippen. It is mounted in a recess in the lower bar (wippen), and it can come loose. In this case, you will not be able to do this in the action. Remove the action (Chapter Five), and remove the wippen. This way you can glue the parts back together and use rubber bands to hold the parts together against the spring tension until dry.

The other problem with grand jacks is that the spring breaks, and one end operates the jack. Please look at the diagram of the Grand Piano Action.

It is possible to embed the end of a new spring in the wood of the repetition lever flange so that it will return the jack to rest. If the jack has a silk thread loop which catches on the return spring, and the thread is broken, drill a small hole through the jack side to side, and run a piece of monofilament fishing line through it. Make a loop similar to the original ones nearby, and tie it off and put a drop of glue on the knot. The jack should function well with this repair.

Some jacks have a small coil spring running under them which pulls the jack back into rest position. Square grands often have this. There is no repair part for this. I have used a small spring, like from a ball point pen. Bend one end to be 90 degrees with the spring. Bend the other so that you can put a tiny screw through the loop, and screw it to the repetition lever flange. Use an awl to make a guide hole so you don't break the flange. To the other end, ties a piece of monofilament fishing line, run it in the groove under the jack, and embed it in the wood of the jack by threading it through a tiny hole you drill. Anchor it with a piece of toothpick and glue it. Avoid putting tension on it until it is dry.

On to task 33