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grand piano (ascr. Franz Jacob Späth ca. 1770) Detail: key fronts

Abb. 1
Abb. 1

P.1: 

Späth grand original, keyboard with bright upper (bone) and dark lower keys (top covers ebony,  front blackened pear).

evidence: key fronts blackened pear (evident by visual examination under the microscope).

Abb. 2
Abb. 2

P. 2: Späth grand original, detail key fronts.

production hypothesis: profiles of the key fronts scraped/cut in circular movement with a turning tool.  plates in full circle profiles subsequently halved.

Abb. 3
Abb. 3

P. 3: 

Making a matching turning tool by filing a matching profile into a card scraper.

Abb. 4
Abb. 4

P. 4: 

Initial material are honed pear boards honed (to 2 mms strength) and cut in length and width to approx. final dimensions. A specific  four-jaw chuck is required. First step is the centering to assist the follwing centering of the grooved tool for scraping.

Abb.5
Abb.5

 P. 5 Turning the profile with slight pressure 


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Abb. 6

P. 6 Completed with full circle profiles

Abb. 7
Abb. 7

P. 7: 

Marking the middle

Abb. 8
Abb. 8

P. 8: 

Cutting in half by saw, the sunk wood scribe mark used as guidance

Abb. 9
Abb. 9

P. 9: 

Halved key fronts after gluing to the keys. Individual adaption of the edge distance to the key top edge by filing.

Abb. 10
Abb. 10

P. 10: 

Key board after finishing blackening by iron gall ink/caseine based ink..

P.11 key fronts replica
P.11 key fronts replica
P. 12 key fronts original
P. 12 key fronts original

work details 

Key fronts
Key fronts

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