Grand Regulation – part XXII

Step 36 – The Backcheck  Distance (continued)
Last month we talked about roughing in the hammer tails and regulating the backcheck bevel. Now we’ll get to the real meat of the subject and cover how to regulate the backcheck distance, along with some pitfalls to watch out for. Going back to the band regulation chart, we see that the key height and key dip directly affect the backcheck distance. An argument can be made that the escapement also affects the backchecking in that if the escapement if set so high that the hammer blocks upon the string, it interferes with the checking. That argument aside, just the key height and dip need be considered.
This seems reasonable since the backchecks are connected to the back of the keys. The keys act as a lever, and certainly changes in the height of the lever at the center, or the amount that the lever goes down at the front will change what happens at the back of the lever. The key height should at this point be correct, as it was regulated as step 12 in the 50-point checklist. However, the key dip may or may not have been regulated for the final time, depending upon the sequence used in section IV The Touch part of the checklist. The sequence used here lists the dip as step 35, the step performed just prior to the backcheck distance. So in this order, we can safely set the backcheck distance without worrying about something changing it as other steps are performed. Keep in mind that the backcheck distance may vary slightly, if the key dip is altered, so if the dip is regulated after the backchecks, some touching up of the checking distance may be needed. This only takes a few minutes, and really is not that hard to do. As was mentioned before, use your fingers when bending the backcheck wires, to insure that the wires bend at the bottom, keeping the bevel the same.

Again looking at the grand regulation chart we see that the backchecks affect only one other step, that being the repetition spring strength. This is sort of stretching the facts if we say that the backcheck distance actually affect the repetition springs. What happens, is that…

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