Thursday, January 16, 2014

The Extra Measure

We stopped by the finishing department this week and noticed a small, flat, spatula-looking tool on one of our finisher's benches.  We hadn't seen this item before, because we visit our finishers at different stages of the finishing process.  So, we just had to find out -- what exactly is this tool?  Well, it is a device that the finishers use to measure the distance between the edge of the key cup and the top of the pad.  Instead of just putting pads in key cups and letting them "fall where they may," this device allows them to measure the distance, which is known as pad "protrusion," so that all the pads are seated with a standard amount of protrusion.

Now, the measure is a standard, and it is a beginning point in the pad seating process.  As we know very well, the finishers spend a great amount of time shimming the pads so that they are not leaking or unevenly seated ("light" or "heavy" in certain areas).  Finishers also work with this measurement tool to make sure that the pad will touch the top of the tone hole evenly.  This is quite challenging since the key itself comes down on the cup at an angle.  If the measurement is correct all around, the pad will touch evenly.  If it is not correct, the front or back of the pad may touch the tone hole too soon.  Once everything is in place and measured, the finishers will take a feeler gauge to the pad and double-check the seating.  The finisher may need to add additional full or partial shims, though.  So, not every pad will remain exactly the same, but the tool certainly helps guide the finishers and creates a standard measure to work with in the process.

Small tool for measuring pad protrusion (directly to the right of the flute).
Red arrow points to even protrusion.  Yellow arrow helps point out that the keys close at an angle.
Uneven protrusion.  Red arrow points to front of pad -- which is too high.  Yellow arrow points to pad protrusion in the back.
Checking pad seating with a feeler gauge.
Side-by-side example: Pad is too high on the top cup, good on the one below it.
Finished footjoint.  Shims may need to be added even after a pad is measured, so pads may not always have the exact same amount of protrusion.

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