Lock Nuts

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Lock nuts are available in a wide range of styles, grades, and finishes. As the name suggests, lock nuts are designed to resist loosening under vibration and load. While they are intended to remain secure once installed, most lock nuts can be removed, and some types can even be reused if removed correctly. Lock nuts are commonly manufactured to ASTM A194 Grade 2H and ASTM A563 Grades A and DH specifications.

At Baseline Bolts Inc. (BBI), we manufacture lock nuts in both standard hex and heavy hex patterns. The two most commonly used styles are Tri-Lok and Anco.

Anco lock nuts are self-locking nuts that feature a stainless steel ratchet pin. As the nut is spun onto the bolt, the pin rides along the threads and prevents back-off. A key advantage of the Anco style is that the ratchet pin can be bent, allowing for easier removal when required.
Tri-Lok lock nuts are prevailing-torque type nuts that resist rotation through controlled thread distortion at the top of the nut, creating frictional resistance against loosening.

Finished Hex Dimensions

Click table to show drawing

Nominal Size	F			C		H			Weight Each (lbs.)
	Width Across Flats			Width Across Corners		Thickness
	Basic	Max	Min	Max	Min	Basic	Max	Min
¹⁄₂	³⁄₄	0.750	0.736	0.866	0.840	⁷⁄₁₆	0.448	0.427	0.04
⁵⁄₈	¹⁵⁄₁₆	0.938	0.922	1.083	1.051	³⁵⁄₆₄	0.559	0.535	0.07
³⁄₄	1¹⁄₈	1.125	1.088	1.299	1.240	⁴¹⁄₆₄	0.665	0.617	0.12
⁷⁄₈	1⁵⁄₁₆	1.312	1.269	1.516	1.447	³⁄₄	0.776	0.724	0.19
1	1¹⁄₂	1.500	1.450	1.732	1.653	⁵⁵⁄₆₄	0.887	0.831	0.28
1¹⁄₈	1¹¹⁄₁₆	1.688	1.631	1.949	1.859	³¹⁄₃₂	0.999	0.939	0.40
1¹⁄₄	1⁷⁄₈	1.875	1.812	2.165	2.066	1¹⁄₁₆	1.094	1.030	0.54
1³⁄₈	2¹⁄₁₆	2.062	1.994	2.382	2.273	1¹¹⁄₆₄	1.206	1.138	0.73
1¹⁄₂	2¹⁄₄	2.250	2.175	2.598	2.480	1⁹⁄₃₂	1.317	1.245	0.94
Dimensions per ASME B18.2.2 1987 (1999)

Heavy Hex Dimensions

Click table to show drawing

Nominal Size	F			C		H			Weight Each (lbs.)
	Width Across Flats			Width Across Corners		Thickness
	Basic	Max	Min	Max	Min	Basic	Max	Min
¹⁄₂	⁷⁄₈	0.875	0.850	1.010	0.969	³¹⁄₆₄	0.504	0.464	0.07
⁵⁄₈	1¹⁄₁₆	1.062	1.031	1.227	1.175	³⁹⁄₆₄	0.631	0.587	0.12
³⁄₄	1¹⁄₄	1.250	1.212	1.443	1.382	⁴⁷⁄₆₄	0.758	0.710	0.20
⁷⁄₈	1⁷⁄₁₆	1.438	1.394	1.660	1.589	⁵⁵⁄₆₄	0.885	0.833	0.30
1	1⁵⁄₈	1.625	1.575	1.876	1.796	⁶³⁄₆₄	1.012	0.956	0.43
1¹⁄₈	1¹³⁄₁₆	1.812	1.756	2.093	2.002	1⁷⁄₆₄	1.139	1.079	0.59
1¹⁄₄	2	2.000	1.938	2.309	2.209	1⁷⁄₃₂	1.251	1.187	0.79
1³⁄₈	2³⁄₁₆	2.188	2.119	2.526	2.416	1¹¹⁄₃₂	1.378	1.310	1.02
1¹⁄₂	2³⁄₈	2.375	2.300	2.742	2.622	1¹⁵⁄₃₂	1.505	1.433	1.31
1⁵⁄₈	2⁹⁄₁₆	2.562	2.481	2.959	2.828	1¹⁹⁄₃₂	1.632	1.556	1.62
1³⁄₄	2³⁄₄	2.750	2.662	3.175	3.035	1²³⁄₃₂	1.759	1.679	2.04
1⁷⁄₈	2¹⁵⁄₁₆	2.938	2.844	3.392	3.242	1²⁷⁄₃₂	1.886	1.802	2.41
2	3¹⁄₈	3.125	3.025	3.608	3.449	1³¹⁄₃₂	2.013	1.925	2.99
2¹⁄₄	3¹⁄₂	3.500	3.388	4.041	3.862	2¹³⁄₆₄	2.251	2.155	4.19
2¹⁄₂	3⁷⁄₈	3.875	3.750	4.474	4.275	2²⁹⁄₆₄	2.505	2.401	5.64
2³⁄₄	4¹⁄₄	4.250	4.112	4.907	4.688	2⁴⁵⁄₆₄	2.759	2.647	7.38
3	4⁵⁄₈	4.625	4.475	5.340	5.102	2⁶¹⁄₆₄	3.013	2.893	9.50
3¹⁄₄	5	5.000	4.838	5.774	5.515	3³⁄₁₆	3.252	3.124	11.94
3¹⁄₂	5³⁄₈	5.375	5.200	6.207	5.928	3⁷⁄₁₆	3.506	3.370	15.26
3³⁄₄	5³⁄₄	5.750	5.562	6.640	6.341	3¹¹⁄₁₆	3.760	3.616	18.12
4	6¹⁄₈	6.125	5.925	7.073	6.755	3¹⁵⁄₁₆	4.014	3.862	21.80
Dimensions per ASME B18.2.2 1987 (1999)