Finer PT 12B1-21PB Pilot Bore Sprocket – 12B-1 Simplex – 3/4″ Pitch – 21 Teeth

The Finer PT 12B1-21PB is a 21 tooth pilot bore sprocket for 12B-1 simplex British Standard roller chain – 3/4″ (19.05mm) pitch. It has a 127.8mm pitch circle diameter (PCD) and a 136mm outside diameter. It comes with a 20mm pilot bore.

A pilot bore sprocket is supplied with a small starter bore so it can be machined out to suit the shaft – keyway and set screws. Finer sprockets are made from high quality steel with induction hardened teeth – improving resistance to wear and extending working life. All Finer sprockets are engineered in accordance with ISO 9000 standards.

Dimensions:

• Hub diameter (dm): 90 mm
• Overall length (A): 40 mm
• Tooth width (B1): 11.1 mm
• Tooth radius (r3): 19 mm
• Radius width (C): 2 mm
• Approx. weight: 2.27 kg
• Chain: 3/4″ (19.05 mm) pitch – 11.68 mm inside width – 12.07 mm roller diameter

BS / ASA interchange (3/4″ pitch – BS 12B-1 and ASA 60-1): BS sprockets will wrap ASA chain (not recommended for frequent forward/reverse indexing) but ASA sprockets will not wrap BS chain unless the teeth are skimmed – the plate thickness differs.

Please note: this pilot bore sprocket is supplied with a 20mm pilot bore – it is not finish bored.

Downloads:

• Finer PT 12B Pilot Bore Sprockets Spec Sheet (PDF)
• Finer PT Sprockets BS / ASA Interchange Chart (PDF)

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