KS 19: Recording Spacing Scale and Strike Heights

KS 19: Recording Spacing Scale and Strike Heights

Setup now complete, record the hammer spacing scale and template heights at strike. The hammer spacing scale comes from the spacing of strings along the strike line as hammers must align with their strings. Whatever traveling, squaring, or spacing we receive in a worn action, hammer wearmarks show where their strings are at strike. So don't touch their traveling, squaring, or spacing (and don't file them) until you record the center of each unison on the Regulating Rack at strike. This will provide a real place to return to as things are changed during the regulation.

If wearmarks are blurred (say by extensive soft-pedaling or loose hammer flanges), or are too faint to read, or are just not there because hammers are new or newly filed, space hammers to strings in the piano first. Then make the record at strike on the bench from the center of each hammer.

The templates, with their fixed location relative to the action, are perfect for recording a copy of the scale. To make the marks, use an Ultra Fine Sharpie pen (part of the Regulation Station packages). Its marks dry unsmudgeable but can be wiped off later with alcohol. Take care not to touch pen to hammer, though. Bringing hammer to template, position the pen above, applying tip to template, and lower hammer and pen together.

At regulation's end, clear marks for the next job or identify and save them. There are four useable edges to each template, so up to three scales can be retained and still have one side free. A saved scale might facilitate setup for an instrument that gets regulated regularly or accelerate the regulating of multiple pianos of the same model as in a university or conservatory. With the templates numbered and named, you would set up to the average and tweak as needed.

Now, record template (strike) heights. If a template accidentally gets knocked or the wrong knob gets turned, if anything happens to make you insecure about template accuracy, this record will save an expensive extra trip to the piano.

Use either Underlevel (combination string leveler and string height gauge) or String Height Gauge and Rail for simple, error-free results. Both house a flat aluminum plunger that can be fixed by thumbscrew and marked through registration holes. The Ultra Fine Sharpie has a tip that fits these holes. With the Gauge on its back, hold the pen vertical to center the mark in its hole. The eye can easily place this mark back in the center to exactly recreate the plunger's height.

Both tools come with their registration holes slanted so results cannot be confused. Five holes provide ten sample heights by using both sides of the plunger. Measure at the outermost marks on each template and write the note numbers on the plunger to identify which were sampled. 

Whichever device is used, make sure its position on the bench (as with that of the action) can be reproduced, eliminating variables due to bench shape. Sharpie marks can wear off with handling, so for a permanent record, use a fine-pointed center punch to indent the plunger (comes with RS Deluxe or Full Monte). For people who cannot see the dot in its hole, the tip of the center punch can locate and center the divot. Write id info at the bottom of each plunger and store to be easily be found. I add Sharpie marks to my divots for better visibility.

For those who lack a Regulating Rack, use your letoff rack, only set it to strike instead of letoff. Working section-by-section, locate the rack (clamping it if possible), add masking tape for the scale, and back the action out temporarily to record end of template heights.

Next week: Key Leveling on the Bench

(Index of all articles in this series)

1 comment

John W. Keane

I love the idea of adding Sharpie marks to my divots. Fore!!! As always, Chris, well-thought out and crisply written! John W. Keane 🎹⛳️🦆🧰

John W. Keane

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