How do I know which chain I have?

Measure the pitch, from the centre of one pin to the next, and the roller diameter. A 1/2 in pitch with a 5/16 in roller is an ANSI 40; the same pitch with an 8.51 mm roller is an ISO 08B; 5/8 in with a 0.400 in roller is a 50 or a 520 motorcycle chain. The chain tables are on the Chain Sprocket page.

Will an ANSI 40 sprocket take an 08B chain?

No. Both have a 12.7 mm pitch, but the rollers are 7.92 and 8.51 mm: an 08B chain on a 40 sprocket rides high in the gap and wears quickly.

How many teeth should a small sprocket have?

Seventeen or more for smooth running; nine to eleven only for slow drives. Below that the chain rises and falls on every tooth -- the polygon effect -- and both chain and sprocket wear quickly.

Chain sprockets

The roller chain sprocket, cut from flat plate. There is nothing to develop: what is calculated is the tooth for the chain, and the ANSI, ISO 606, motorcycle and bicycle chains fill in with one click.

Chain Sprocket

Chain sprocket generator: the ISO 606 tooth for ANSI, ISO 08B, motorcycle and bicycle chains, with the pitch, outside and root diameters and a DXF.

Which sprocket to use

Drive or driven sprocket for a roller chain, ANSI, ISO 606 B series, motorcycle or bicycle: Chain Sprocket.
A sprocket with no bore, to finish on the lathe: the same Chain Sprocket, with a bore of zero.
A gear that meshes with another gear is not a chain sprocket: its tooth is an involute, and it is not in this catalogue.
A plate flange with standard drilling, the other part born flat: Flange.

How it is calculated

The roller centres sit on the pitch circle, d = p / sin(180°/z), one per tooth. Around each one the tooth gap is the ISO 606 form: a roller seat a little larger than the roller and two flank arcs tangent to it, up to the outside diameter.

The dimensions are the number of teeth, the chain pitch and roller diameter, the bore and the plate thickness. The result comes with the pitch, outside and root diameters, the PDF template at 1:1 scale and the DXF for plasma or laser.

Frequently asked questions

How do I know which chain I have?: Measure the pitch, from the centre of one pin to the next, and the roller diameter. A 1/2 in pitch with a 5/16 in roller is an ANSI 40; the same pitch with an 8.51 mm roller is an ISO 08B; 5/8 in with a 0.400 in roller is a 50 or a 520 motorcycle chain. The chain tables are on the Chain Sprocket page.
Will an ANSI 40 sprocket take an 08B chain?: No. Both have a 12.7 mm pitch, but the rollers are 7.92 and 8.51 mm: an 08B chain on a 40 sprocket rides high in the gap and wears quickly.
How many teeth should a small sprocket have?: Seventeen or more for smooth running; nine to eleven only for slow drives. Below that the chain rises and falls on every tooth -- the polygon effect -- and both chain and sprocket wear quickly.

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