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Recently, another technician inquired about how a broken piano agraffe can be replaced. I wrote up the following procedure:

Agraffe Replacement
Occasionally, an agraffe head will break from its stem. It will most often be in grand pianos but can also occur in verticals. This will probably be a one hour service call fee plus materials. Here are the steps:

1. Loosen the two or three wires involved by turning the tuning pins ¾ of a turn counterclockwise. Remove the becket and coils from the tuning pins. Cut off the beckets. Using long nose Vice Grip pliers, straighten out the coils so that the broken agraffe head can be removed and the wires can later be threaded through the new agraffe. If it is old plain wire involved, it may be preferable to replace the wire but this will necessarily mean repeated service calls to re-tune the new wire. Re-using the existing wire will largely avoid service calls to re-tune.

2. If the agraffe stem is not firmly lodged in the hole, it can be removed by turning it counterclockwise. Start by lightly tapping with an awl and small hammer until there is enough of the stem protruding from the hole to grab with snub nose Vice Grip pliers. Continue turning counterclockwise until the agraffe stem exits the hole. It is seldom that the stem is firmly lodged within the hole but if it is, it can still be removed. First, drill a tiny pilot hole about 1/8-3/16” (a few mm) in the stem with a very small drill bit. Then, put a small "easy out" drill bit in the drill. The "easy out" bit has a reverse thread, so it penetrates when the drill is in reverse mode. Insert the “easy out” bit in the pilot hole and start the drill slowly in reverse mode. It will penetrate the hole and lodge itself into the remnant and remove it. (This is also the same procedure for extracting a broken bolt).

3. Insert the new agraffe and begin turning it clockwise first with gloved fingers and then with blunt nose Vice Grips pliers. There is a special tool for this purpose but it isn’t necessary unless a whole new set of agraffes is being installed. However, a piece of buckskin or bushing cloth between the Vice Grip pliers and the agraffe should be used to prevent marring it. Now, turn the agraffe all the way clockwise until it is tight and also perpendicular to the strings. There is a little tolerance. If the agraffe stops before it is at the proper orientation, it can be forced a little more but not too much or it may break. Similarly, it can be just barely tight but it should not be loose.

4. If the agraffe cannot be properly oriented without being either too tight or too loose, there are some small and very thin special brass washers called "agraffe shimming washers". Remove the agraffe and put a washer around the stem and try again to seat the agraffe to the proper orientation. Usually, one washer suffices. No more than two washers should be used because that will cause the string height to be on a higher plane than all of its neighbors. Another technique can be used if the agraffe is slightly too tight to get the proper orientation. Use a fine file to remove a bit of material from the bottom of the agraffe head. Each item mentioned here can be obtained from the usual Piano Supply merchants: agraffes, agraffe shimming washers, easy out drill and strips of buckskin.

Agraffe replacement often takes a bit more finesse:

1. Loosen the strings 1/2 turn, that is all that is needed to remove the beckets and minimizes loosening of the block. If you leave the strings in the broken head of the agraffe with a clamp on them, they will remain out of the way until time comes to re-install. After cutting the beckets off, it is important that the last 5mm or so of the wire be straight so as to facilitate the forming of the new becket without having to fight to keep the wire in the hole.
2. A loose post is sometimes found to be easy to tap out, but when it is frozen in place, a more careful technique will be required. A reverse spiral drill is the preferred way, as it will sometimes spin the stud out. Careful centering of the initial punch, and attention paid to the angle is critical to leaving undamaged threads. Drilling into brass is best done with higher speed and slower feed, since an overly cautious approach with too low rpm will dig the bit in to the softer metal and break it off,(which can double the cost of repair).
I have never seen a machinist use an EZ-out in a drill, only by hand in a T-handle. EZ-outs can easily swedge the broken remnant in place and I have more than once been called to deal with a broken off drill bit and/or EZ-out, (they are hardened steel and take a lot of care to grind out without damaging a plate.)
3. The installation of a new agraffe has three imperatives; it must be oriented properly, it must be at the right height, and it must be tight. Modern agraffes have a beveled face on their mating surface which is there so that the final 20 or so degrees of rotation can firmly seat the joint as it arrives at its final orientation. The brass will slightly deform under the torque needed to do this, which means that the correct agraffe will contact the plate before it is aligned properly, and it takes some experience to know how much deformation is required for a tight fit at the proper alignment without over-stressing the brass. Using washers is normal, and on occasion one or more are required to leave the agraffe at a matching height for the others. (not all plates are machined perfectly, and not all replacement agraffes match the originals.) With a hollow end-mill, we can reduce the fitting surface, but the best approach is to have at least 6 or 7 replacement agraffes so that one may align correctly without excessive fitting.

The replacement of agraffes is a normal part of our job, but is best done with the proper tools. We now have repair threads that can be used if the plate is damaged by incompetence, but it is best to avoid broken bits and EZ-outs, (I have been called in to remedy these situations and it can be nerve-wracking) Vise-grips and EZ-outs are not the optimum way of doing this, since there are tools made specifically for the work that insure a higher probability of doing the job to professional standards,(i.e. a tightly anchored agraffe at the proper height and orientation should be an invisible repair).
Regards,

+100.

EZ-outs must not be used in a drill. They are supposed to self tap in the drilled hole and then be turned gently so as not to overstress their marginal purchase on the compromised bolt they seek to remove. Using a drill risks reaming out the hole, making subsequent attempts less likely to succeed, or breaking the EZ out, which leads to even worse problems than you started with. I'm surprised that anyone who has used an EZ-out would recommend this practice. The slower you use them, the better your chances.

The string holes in new agraffes are drilled higher than the holes on older Steinways so if you are replacing a single agraffe, you will need a way to trim the bottom of the new agraffe to match the originals. Pianotek sells a tool for this that works well. You can also drill a hole in a piece of hardwood and glue some sandpaper on top and spin the agraffe in the hole with a drill and an appropriate adapter. It's a little slow, but will get the job done.