I only weigh off well-regulated actions. The objectives of weighoff are balance and consistency, and erratic or inappropriate elements in regulation, including those of friction, inertia, and geometry, will interfere with balance and consistency whatever the weighoff.
Most full regulations I have performed were the first for that piano since it was new, suggesting that many (or most) pianos never receive this benefit. Complexity and costliness can make even experienced technicians wary of selling regulations. Too many unknowns, too many variations on unanticipated problems, and too high a price tag if you get it wrong. Touch-ups work adequately well in most situations and satisfy the customer when not compared to the proper job.
But pianos falling short of potential disappoint, frustrate, and annoy long before they fail. And our work life can be greatly enhanced by the change of pace and greater benefits that deeper regulations offer.
I do this work largely out of the piano. Drop, backchecks, spring tensioning, jack and rep lever positioning, and friction are adjustments that cannot be made in the piano. And keys, keyframe, and topstack all benefit from being regulated on a bench in good light at an ergonomic height with 360 degree access and no customer hovering. This approach (see my protocols) sets up bedding and strike on the bench to match what they were in the piano and the tools make prepping and regulating global procedures (as opposed to sectional). The process is linear, steps leading to next steps, while not undoing previous steps.
In the piano, I bed the keyframe (validating all aspects with the action fully assembled) and take Keystep samples of bedding and weighted kissing samples of strike. Once bedding is in place on the bench, the strike samples will be accurate and I set up the Regulating Rack to these, recording the resulting template heights with the String Height Gauge and marking the hammer spacing scale along the strike edges of the templates. The Regulating Rack's template rail then takes the entire profile of strike down to hammerline, up to letoff, or back to strike. With stops above and below to auto-position the rail at strike and hammerline, respectively, and with Gauge Keys providing blow, backchecking, and letoff distances, moving from one position to the next takes seconds.
If needed, I rough in key level, letoff, drop, backchecking, and springs – this does not take long. I then fully regulate three contiguous notes (two naturals with a sharp in between) to consider what’s there. Invariably, details emerge. Among other things, I check downweight and upweight and with this information decide what in the action parts, materials, and setup can be kept and what must be changed. The working specs for this regulation are now in place.
Next, I prep parts, including filing hammers, repinning centers (principally shank and rep lever), and making parts vertical. Then I square, space, and level keys, rough in hammerline, letoff, and drop (as needed), set dip to specs, do backchecks, springs, rep lever heights (winking), jack positions, hammerline, letoff, drop, and finally aftertouch (by refining dip) - in this order. All this is done on the bench. Now, weighoff and a quick regulation touch-up. Then, back to the piano for string-to-hammer fit, dampers, pedals, tuning, and voicing.
Granted, there are many steps if you do them all. But I go out to the bench just once, the regulating there goes really fast, and back in the piano, the work fits. String leveling and mating proceed in one operation. Dampers regulate well to the well-leveled strings. And the action is balanced and extremely consistent. But weighoff is the feature that assures results will exceed expectations, the key to best perceived value and happy customers.