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Precision Sprockets Caliper Diameters per ANSI/ASME B29.1M

Mechanical Components
ANSI ASME Mechanical Hardware

Tolerances for Caliper Diameters of Precision Chain Sprockets ANSI/ASME B29.1M

Caliper diameter is the same as the bottom diameter for a sprocket with an even number of teeth. For a sprocket with an odd number of teeth, it is defined as the distance from the bottom of one tooth gap to that of the nearest opposite tooth gap.

• The caliper diameter for an even tooth sprocket is equal to pitch diameter–roller diameter.
• The caliper diameter for an odd tooth sprocket is equal to caliper factor–roller diameter.
• Caliper factor = PD[cos (90° / N)], where PD = pitch diameter and N = number of teeth.
• Caliper factors for 1-in. pitch and sprockets having 9 to 108 teeth are given below in the table.

Caliper diameter tolerances are minus only and are equal to:

Commercial Spockets

Precision Spockets

Minus Tolerances for Caliper Diameters of Precision Chain Sprockets ANSI/ASME B29.1M

Pitch	Number of Teeth
	Up to 15	16 to 24	25 to 35	36 to 48	49 to 63
0.250	0.004	0.004	0.004	0.005	0.005
0.375	0.004	0.004	0.004	0.005	0.005
0.500	0.004	0.005	0.0055	0.006	0.0065
0.625	0.005	0.0055	0.006	0.007	0.008
0.750	0.005	0.006	0.007	0.008	0.009
1.000	0.006	0.007	0.008	0.009	0.010
1.250	0.007	0.008	0.009	0.010	0.012
1.500	0.007	0.009	0.0105	0.012	0.013
1.750	0.008	0.010	0.012	0.013	0.015
2.000	0.009	0.011	0.013	0.015	0.017
2.250	0.010	0.012	0.014	0.016	0.018
2.500	0.010	0.013	0.015	0.018	0.020
3.000	0.012	0.015	0.018	0.021	0.024
Pitch	Number of Teeth
	64 to 80	81 to 99	100 to 120	121 to 143	144 and up
0.250	0.005	0.005	0.006	0.006	0.006
0.375	0.006	0.006	0.006	0.007	0.007
0.500	0.007	0.0075	0.008	0.0085	0.009
0.625	0.009	0.009	0.009	0.010	0.011
0.750	0.010	0.010	0.011	0.012	0.013
1.000	0.011	0.012	0.013	0.014	0.015
1.250	0.013	0.014	0.016	0.017	0.018
1.500	0.015	0.016	0.018	0.019	0.021
1.750	0.017	0.019	0.020	0.022	0.024
2.000	0.019	0.021	0.023	0.025	0.027
2.250	0.021	0.023	0.025	0.028	0.030
2.500	0.023	0.025	0.028	0.030	0.033
3.000	0.027	0.030	0.033	0.036	0.039