I completed some more work related to the key frame, and the mind is spinning with plans for the next steps. As I move ahead, I invite my piano technician friends to comment on what you see and infer here. It is only by using the best of the best ideas that I can hope to achieve excellence with this project.
Key frame observations
I’ve had the action in and out of this piano many times in the past 10 years, but upon examining things for rebuild, I do see a few things in a different light. Of interest: the bottom of the front rail. It is flat. There is no raised edge at the front to allow for mating with the keybed. Instead, as the photos below show, there are three springs plus the end blocks which snug the keyframe down to the keybed. The system is still working well 104 years later. In the past, I’d adapted to the presence of these springs on removing and installing the action, but I had not appreciated their practical effect. Note that the center rail is notched at an angle (front to back slope), so that the center rail will slide up and over the springs on the way out.
While bare, the keyframe received new, slick WNG anodized aluminum glide bolts:
New back rail cloth was installed as per the original with an inner cloth creating a raised profile. I used fish glue to install. Also, new feet (at a new height) were installed for the new action frame. Hammer flange center pin height was determined using methodology of Wessel, Nickel and Gross.
New action frame sits upon the reconditioned key frame (approximately in position for now)
While preparing to install new WNG keypins, I built a 6 foot table for the drill press this afternoon.