Shoulder Bolts: Dimensions and Specifications

Labeled Diagram of Socket Shoulder Screws

Socket Shoulder Screw Dimensions (Alloy Steel) ASME B18.3-2003
Nominal Size Click on the size to shop products	Shoulder Diameter (D)		Head Diameter (A)		Head Height (H)		Chamfer or Radius (C)	Hex Socket Size (J)	Key Engage-ment (T)	Fillet Transition Diameter (M)	Head Fillet Radius (R)	Shoulder Neck Diameter (K)	Shoulder Neck Width (F)
Nominal Size Click on the size to shop products	Max	Min	Max	Min	Max	Min	Max	Nom	Min	Max	Min	Min	Max
1/4	0.2480	0.2460	0.375	0.357	0.188	0.177	0.020	1/8	0.094	0.276	0.009	0.227	0.093
5/16	0.3105	0.3085	0.438	0.419	0.219	0.209	0.026	5/32	0.117	0.345	0.012	0.289	0.093
3/8	0.3730	0.3710	0.562	0.543	0.250	0.240	0.031	3/16	0.141	0.413	0.015	0.352	0.093
1/2	0.4980	0.4960	0.750	0.729	0.312	0.302	0.040	1/4	0.188	0.550	0.020	0.477	0.093
5/8	0.6230	0.6210	0.875	0.853	0.375	0.365	0.050	5/16	0.234	0.687	0.024	0.602	0.093
3/4	0.7480	0.7460	1.000	0.977	0.500	0.490	0.069	3/8	0.281	0.826	0.030	0.727	0.093

Socket Shoulder Screw Dimensions (Alloy Steel) - Continued ASME B18.3-2003
Nominal Size Click on the size to shop products	Nominal Thread Size (D1)	Threads per Inch	Thread Neck Diameter (G)		Thread Neck Width (I)	Thread Neck Fillet (N)		Thread Length (E)	Thread Section Tensile Strength (lbs.)	Single Shear Strength (lbs)		Seating Torque (in./lb.)
			Thread Neck Diameter (G)			Thread Neck Fillet (N)		Thread Length (E)	Thread Section Tensile Strength (lbs.)	Shoulder	Thread Neck
			Max	Min		Max	Min	Basic	Min	Max	Min
1/4	10	24	0.142	0.133	0.083	0.023	0.017	0.375	2,540	4,515	1,250	50
5/16	1/4	20	0.193	0.182	0.100	0.028	0.022	0.438	4,610	7,100	2,340	125
3/8	5/16	18	0.249	0.237	0.111	0.031	0.025	0.500	7,600	10,280	3,970	265
1/2	3/8	16	0.304	0.291	0.125	0.035	0.029	0.625	11,240	18,350	5,985	470
5/8	1/2	13	0.414	0.397	0.154	0.042	0.036	0.750	20,570	28,785	11,140	1,150
3/4	5/8	11	0.521	0.502	0.182	0.051	0.045	0.875	32,770	41,515	17,800	2,000

Socket Shoulder Screws : Nominal Screw Length
Tolerance on Length	Nominal Screw Length
	Up to 3/8" (Inclusive)	Over 3/8"
	-0.02	-0.03

Socket Shoulder Screw Mechanical Properties ASME B18.3-2003
Description		A hex head socket screw with an enlarged and unthreaded cylindrical shoulder under the head. The diameter of this shoulder serves as the basis for deriving the nominal size.
Applications/ Advantages		Commonly used in rotation and sliding applications, such as pulley shafts Useful in punch and die work Can be used as a bearing pin Also known as "stripper bolts"
Material		Made from alloy steel with a sufficient amount of chromium, nickel, molybdenum or vanadium to meet the strength requirements outlined below.
Heat Treatment		Set screws should be heat treated via oil quenching from above the transformation temperature and then tempered at a temperature that is not lower than 650-degrees F.
Hardness		Rockwell C32 - 43
Tensile Strength		140,000 psi, minimum (material only)
Yield Strength		120,000 psi, minimum (material only)
Elongation		15% minimum (applies to all machined specimens of length at least 4D where D equals the nominal diameter of the screw)
Reduction of Area		45% minimum (applies to all machined specimens)
Finish		Usually offered with a plain finish

Frequently Asked Questions:

How to measure socket shoulder screws

Inch Shoulder Bolts:

1. List shoulder diameter, then

2. List thread diameter/size, then

3. List shoulder length

Example: 1/4"-10-24 x 7/8" = a shoulder bolt with a 1/4" diameter shoulder, #10-24 thread size and 7/8" shoulder length

Thread size is one standard size smaller than the shoulder diameter and doesn't need to be specified, except for:

Metric Shoulder Bolts:

1. List shoulder diameter, then

2. List thread size, then

3. List shoulder length

Example: M6-M5 x 20 mm = a shoulder bolt with a 6 mm shoulder diameter, a 5 mm thread diameter and 20 mm shoulder length