Involute Spline Names, Symbols, and Relations for ANSI Standard

Term		Symbol	30 deg ϕ D			37.5 deg ϕ D	45 deg ϕ D
			Flat Root Side Fit	Flat Root Majot Dia Fit	Fillet Root Side Fit	Fillet Root Side Fit	Fillet Root Side Fit
			2.5/5 - 32/64 Pitch	3/6 - 16/32 Pitch	2.5/5 - 48/964 Pitch	2.5/5 - 48/96 Pitch	10/20 - 128/256 Pitch
Stub Pitch		P_s	2P	2P	2P	2P	2P
Pitch Diameter		D_s	N/P	N/P	N/P	N/P	N/P
Base Diameter		D_b_s	D coc ϕ_D	D cos ϕ_D	D cos ϕ_D	D coc ϕ_D	D coc ϕ_D
Circular Pitch		p_s	π/P	π/P	π/P	π/P	π/P
Minimum Effectice Space Width		s_v_s	π/(2P)	π/(2P)	π/(2P)	(0.5 π + 0.1)/P	(0.5 π + 0.2)/P
Major Diameter, Internal		D_ri_s	(N + 1.35)/P	(N + 1)/P	(N + 1.8)/P	(N + 1.6)/P	(N + 1.4)/P
Major Diameter, External		D_o_s	(N + 1)/P	(N + 1)/P	(N + 1)/P	(N + 1)/P	(N + 1)/P
Minor Diameter, Internal		D_i_s	(N - 1)/P	(N - 1)/P	(N - 1)/P	(N - 0.8)/P	(N - 0.6)/P
Minor Dia. Ext.	2.5/5 thru 12/24 Pitch	D_re	(N - 1.35)/P		(N - 1.8)/P	(N - 1.3)/P	...
	16/32 Pitch and finer				(N - 2)/P		...
	10/20 Pitch and finer				...		(N - 1)/P
Form Diameter, Internal		D_Fi	(N + 1)/P + cF	(N + 1)/P - 0.004 + 2cF	(N + 1)/P + 2cF	(N + 1)/P + 2cF	(N + 1)/P + 2cF
Form Diameter, External		D_Fe	(N - 1)/P - cF	(N - 1)/P - 2cF	(N - 1)/P - 2cF	(N - 0.8)/P - 2cF	(N - 0.6)/P - 2cF
Form Clearance, Radial		c_F	0.001 D, with max of 0.010, min of 0.002