I tried to search in piano anatomy and glossaries but couldn't find any result. I also tried google search with image and it incorrectly identified my picture as "webbing". Can anyone help me identify the tool I can use to turn this particular kind of screw in upright piano? (Or tell me how to find related resources?) See picture below.

enter image description here

1 Answer 1


That screw is known as the "let-off regulating screw" (see part #28 in the linked diagram). Yours appears to be a "spade screw" (below). To adjust it, you need a "Piano let-off regulating screwdriver" like the one shown below.

space screw
spade screw

Regulating screwdriver
Regulating screwdriver
(Image source)

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