Each string of the instrument requires a specific tension to be tune-up (6 to 10 kg).
This adjustment is provided by the locking of the shank of the peg in the head of the instrument.
This is an old but reliable and nice mean when it works well.

See: historical evolution

Bois d'Harmonie Pegs

French Pegs

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Strad Peg

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Heart Peg

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Baroque Peg

Technical notes

All pegs are made in 3 wood species : Boxwood, Rosewood and Ebony.

Only heart and baroque pegs models are made in pernambuco.
Rings and pins can be made of Ebony, stained and unstained boxwood, or vegetal ivory (Tagua nuts). We don't use ivory any more. Olivettes are brass or gold. Maximum diametre of the pegs shanks:
Violin 8.8mm ; Viola 9.4mm ; cello 13.8mm. Modern shank slope 1/30.