cashmere replacement

Removal can be done with steam or with wallpaper stripper diluted in water. It depends on which glue was used. Use only natural glue in a bain-marie. The new felts must be glued with cauls calibrated according to the type and caliber of the round and oval pins. The choice of cashmere thickness and, above all, quality, must be rigorous. For voicing, exclude common clips that do not exert sufficient "parallel" pressure on the walls of the mortises and are rather imprecise. Furthermore, a special plier is necessary to correct and calibrate the smoothness of the keys after voicing and regulation. It is a job that requires some experience.

I thank you very much, always very kind. Regards.

Could you please indicate how many mm of depth inside the key the new cashmere must have? Thank you.

about 3-4 mm

Always very kind Maestro Ferrarelli, greetings.

I am following up on Placido's request because I also have some trouble identifying the correct thickness of the buckskin for the keys of my piano (a BREMITZ upright from the early 1900s).

The central pin (cylindrical) measures 3.50 mm, while the mortise hole measures approximately 4.50 mm. Consequently, I should use a 0.5 mm buckskin to ensure there is no play, but I cannot find such a thin size available. How can I obtain it?

Instead, in the pin at the start of the key (oval with a "width" of 3.3 mm), I have a measured hole of about 3.9 mm. Consequently, here I should use a 0.3 buckskin.

These measurements seem a bit small to me.

Regarding the glue, is it better to use rabbit glue or hide glue?

Lastly, I have no problem creating the necessary brass cauls myself if needed (I cannot find them in these sizes), but actually, at what dimension should I make them (for example, for the 3.5 mm cylindrical pin, cauls of 3.55 or 3.60 mm?)

Thanks in advance for the help!

With cashmere, you have to do some testing. The important thing is that, especially in the front mortises, there must be a minimum amount of play. The math probably doesn't add up because in the past some used leather (which does not slide), very infrequently, and therefore the mortise is too tight. I also recommend changing the pins; otherwise, oxide or rust will soon consume the gaskets. Naturally, since I cannot see them, I am assuming. So everything must be seen up close. If you have a precision milling machine, you can attempt to widen the mortise, which however must still be perfectly centered. Experience, of course, helps, so experimenting yes... here one can make mistakes.... and go backwards. The glue, as long as it is hot water bath glue (do not exceed 60°). Zurich-type beads, I believe it is leather.

Thank you very much for the info.

Looking at the material in the front key slots, it doesn't seem to be felt, but it is certainly very thin.

I will try to see if I can find someone with a CNC milling machine, then I'll see what to do.

In the meantime, I will try to fix only the problematic keys, so I will decide what to do at a later stage.

Thank you very much for your availability and the precious information you gave me.