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(1) Makeshift: Reducing a pegs diameter by 50 percent doubles sensitivity when tuning while the peg
remains stable enough.
This solution comes close to what a fine tuning peg does while reducing expences.
Professional finetune pegs are produced by e.g.
(2) Wittner GmbH (G), if you can accept the plastic appearance of these pegs,
(3) Eureka Instruments (G), (Knilling) if these pegs are long enough for your instrument,
(4) PEGHEDS (USA)