KS 13: Preparing for Bedding, Key Level, and Strike Samples

KS 13: Preparing for Bedding, Key Level, and Strike Samples

Choose which keys will be bedding samples, naturals only, one beside each glidebolt including hidden ones (glidebolts are the balancerail's points of greatest stability and adjustment sensitivity). And choose a mid-range leveling sample (E44). Then, remove front punchings from these samples to a machine screw provided by Sampling Kit or Leveling-Sampling Kit. In their place, install Keysteps, also from the kit. They come in two sizes to accommodate different lengths of front key pin (and therefore different amounts of space available between key and keyframe). The taller Keystep has both a longer screw (12mm) and a taller base, needing more minimum space and having a longer reach than the smaller Keystep (10mm). The new Leveling-Sampling Kit has seven of each size, six for bedding samples and one for mid-range leveling sample.

The Leveling-Sampling Kit also contains Rocke Sharp Leveling Blocks (shown above on the left). And other items in the kit include a Combination Ratcheting Wrench for adjusting Keysteps, a 200 gram weight for preventing measuring error in strings flexible enough to deflect (mostly string #3), and a WNG Dip Tool, which provides fixed-position weight for strike sampling.

Keysteps have a slot that fits over its note's oval front key pin and prevents it from spinning around. To be accurate and stable, Keysteps need to sit on keyframe wood, so remove all front punchings. The slots come countersunk to clear those pins with shoulders above grade and its 12mm or 10mm screw has a snug fit, requiring the wrench for an adjustment that won't change between sampling and setup. Keep the punchings in order on the machine screw to return them as they were to their respective pins when done.

Once Keysteps are in place for each glidebolt and the mid-range key level sample, choose the closest naturals to the bedding samples for strike samples, plus one for where two templates in a long tenor section will meet, and remove their punchings to the other machine screw. The photo below shows punchings cleared for A37, which for this Steinway A is the transition note between upward sloping tenor and more-or-less flat mid-range. Two templates minimize errors that would result from using only one template for the section.

Notice seven notes worth of punchings on the right-hand machine screw, nine on the left. There will always be more strike samples so the two groups will not get confused. Methodically, start punching storage from one end of the frontrail and return them to their key pins from the other.

Weighted samples of strike block and then "let off" hammers, needing extra follow-through. Strike sample jacks must lift their hammers beyond normal letoff to the strings and beyond that to clear knuckles as the blocking hammers "let off".

So, the keybed is clean, keyframe fully bedded, sample punchings cleared, Keysteps on, cheekblocks bedded, and cheekblocks secured. If we had no friction, spacing, or repair issues, we are now about 20 minutes into the job. And it's time to methodically take our samples, pack action and tools, return case parts to the piano, and depart for our work on the bench. 

An added note: Two weeks ago, I outlined a radical solution to a glidebolt-less keyframe with difficult-to-solve bedding issues. This week, I was asked the logical question I failed to answer there, how to set up on the bench a well-bedded glidebolt-less keyframe. My answer employed a Custom Keybed (part of the Deluxe and Full Monte Regulation Station packages) but could, more awkwardly, work by shimming on any solid surface. Place bedding platforms (or shims - the back and front rails will need shimming, too) where glidebolts would go if there were room (i.e., ends of keyframe, between sections, middle of a long section) and treat the keyframe underside as if each point of contact was a glidebolt. You just need the keyframe to sit on the bench with the same shape it had in the piano. Although the keyframe may distort when it leaves the keybed, it will be inclined to go back to its accustomed shape, given a little help. And points of support (bedding platforms, glidebolts, or shims) work well as demonstrated by glidebolt use in virtually all modern pianos.

Next week: Bedding and Key Level Sampling

(Index of all articles in this series)


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