Fingertech's S3M Timing Pulleys and Belts are a good solution for transmitting power from motors to wheels or shafts. 

A range of ten pulley sizes means there are 55 different ratio combinations to choose from! 
Use with our selection of Fingertech Timing Belts, or any other 3mm pitch belt (4mm wide or less). 

Fingertech's Pulley-Belt Distance Calculator will let you pick from our available pulley and belt sizes and tell you how far apart they will be, OR plug in your desired distance and it will tell you which belt to use.

Specifications

• Pitch (distance between tooth center) - 3mm
• Belt Width (max) - 4mm
• Material - 6061 Aluminum
• Sizes 9t to 42t 
• Bore 3mm (9t, 15t, & 16t can be drilled up to 5/32", larger pulleys can be drilled up to 1/4")
• Includes 4-40 setscrew for attaching to a shaft.  Make sure your motor or shaft has a flat spot.  
• Setscrew requires 0.05" hex wrench

# Teeth	Pitch Diameter (for calculating centers)	Outside Tooth Diameter	Weight
9T	8.59mm (.338")	7.89mm (.313")	1.4g (0.05oz)
15T	14.32mm (.564")	13.56mm (.534")	3.3g (0.11oz)
16T	15.28mm (.602")	14.52mm (.572")	4.0g (0.13oz)
18T	17.19mm (.677")	16.43mm (.647")	5.3g (0.18oz)
22T	21.01mm (.827")	20.25mm (.797")	7.8g (0.28oz)
26T	24.83mm (.977")	24.07mm (.947")	10.5g (0.38oz)
30T	28.65mm (1.128")	27.89mm (1.098")	13.5g (0.48oz)
34T	32.47mm (1.278")	31.71mm (1.248")	16.3g (0.55oz)
38T	36.29mm (1.429")	35.53mm (1.399")	21.0g (0.73oz)
42T	40.11mm (1.579")	39.34mm (1.549")	26.3g (0.90oz)

Pulley Size Chart (mm)