> Good luck, > Bob Davis > Stockton, CA Dear Pam, What Bob Davis wrote is quite correct and holds true to any action, it is the "feel" that is more important than the specifications. An exact number is far less important than consistency. Very level keys is a good beginning. Letoff can be done two ways, carefully watching the hammer as it comes up to the string and adjusting the letoff so the hammer comes to twice the thickness of the string (bass three times the thickness of the core). Hammer movement has to be very slow to gauge this accurately. I prefer to use a magnetic gauge (car sign making material) that is 1/16" thick) and lift the hammer to the string with a hook made from coat hanger material and work the key and adjust the letoff until I can feel the jack brush the knuckle. By varying the amount of brush I can taper the letoff from bass to treble . In the bass I use tape to hold the gauge to the strings. I have five pieces, 6,6,5,4,3". This combination will allow fit for any section size. Jack position and engagement is very important. I adjust the first and last visually then adjust all the rest to feel exactly the same by referring often to my two samples. No matter the size or shape of the knuckle I will get consistent engagement. By lightly placing the middle finger on the shank, the thumb moves the toe of the jack in and out and the right hand (left if you are strange that way) handles the tool. I adjust the height of the rep. lever by sensing the amount of brush on the knuckle when the jack is moved in and out (again with the thumb). I want to feel a brush but the jack must be able to get back to it's rest position under it's own spring tension. These two have to be recheck after the spring tension is adjusted. At this point you must set samples of all the regulation points to determine values for dip and hammer height. Play with three to five keys around middle C. Essentially play with drop, dip and blow until you get the feel you are looking for. Begin with 1.75" blow and .040" dip. If you change one you have to check the other two because they are interdependent. When you are done put .040" to .050" of paper under some of the keys and determine if you have letoff or not. If not make the dip deeper until you just barely do with a firm pressure on the key. If there is a definite drop the dip is too deep. Play with these until you get a sense of what the differences are. Doing dip is not as easy as it first appears. Again consistency is paramount. Play the note with the same amount of force each time, feel across the front edge of the block (not the middle) and do only the naturals. You must know the thickness of your dip block. Measure at each front corner with a micrometer with the anvil flat on the bottom of the block and sand the bottom until you get exactly the same reading at both corners then write that number upon the block itself. Do this for all of your blocks. If you wish a measurement different than the block then you can add or remove a specific amount of paper after setting each key. _Then_ play three keys and feel for inconsistent level. Play the next three but only up one key. Do this all across the keyboard and making adjustments as needed. Now set samples of blow and drop at each section end to duplicate exactly the same feel as your earlier samples. You can only do the naturals, naturally, because the dip is only done on those keys. If you wish you can do the same for notes a fifth or a fourth apart for better results. Level the hammers by eye. Drop is done while simultaneously doing sharp dip. The idea here is to set the dip on the sharp to make it feel exactly like it's neighbor naturals (and changing the dip when you make a change in drop). This is a back and forthing process which provides the most accurate means of doing dip on sharps. 1/16" drop from top dead center of hammer rise is the specification. Mechanically the letoff button and jack toe come together at the same time the drop screw and rep. lever come together. There should never be a step engagement and 1/6" does just this. Checking is 1/2" below drop. Get one of those steel rules that is 1/2" wide and use it as a gauge for consistency. Use 80 grit sand paper to clean and roughen hammer tails. The tail should be rounded at a 2 to 2 1/2" radius. If this is not so checking will not work well. Rock the hammer and key up and down with considerable weight on the hammer to make sure the hammer tail and backcheck will not interact under a hard blow. Backchecks will not be in a perfectly straight line. The rise of the sharps is greater than the naturals because of the length of the lever of the key. Movement of the sharp must be the same as the natural at the capstan not the key end, except on uprights. It is the amount of work the key does that is important to keep consistent. If you see one backcheck out of line with it's mates double check dip and hammer tail placement. Wippen springs are two arms with a coil in the middle and can only be adjusted by opening and closing the arms relative to each other and NOT bending the arms. If the spring is too strong you use a hook to push the upper spring arm down to wind up the coil and if it is too weak you take the spring out of it's seat and lift up the arm at the support post to unwind the coil. It is tricky and it takes practice but you can get very consistent results this way. Never consider bending the spring arms unless you have an extreme situation and then only after considering every other possibility. Pinning is critical at the rep. lever pivot. If it is too tight you will get too strong springs and impede touch and if it is too weak spring tension will be too low and will severely impede repetition. If the lever falls of it's own weight it is too weak. Two to three grams tension measured at the long end of the lever is the specification. Hammer rise should be at the same rate as your hand would rise to toss a tennis ball one to two inches into the air. Slower impedes repetition and faster makes the hammer bounce upon release from checking and could strike the strings again and certainly feels unpleasant. Be patient this takes a little time to practice and get good at. Recheck jack position and rep lever height as above. Recheck your hammer line. All this can and should be done at the piano. As discussed earlier benches are not the same as keybeds so dip has to be done with the action in the piano and drop and others can be on top of the piano after making sure the dip is exactly the same as in the keybed. Use a towel or newspapers to protect the finish and shims and wedges to get the dip you need. Work with one section at a time because setting the dip the same for each section is not possible with most keyframes. Now check each and every key, multiple times, and make minor adjustments to touch by varying dip a little but watch your hammer line. Now that action should feel good and so should you. By being consistent and exact at each step will give you superior results and you will not need to go back and do something again. Now tuning and voicing are next. End of lecture. Newton
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