ntsqd
Well-Known Member
There are charts for compensating the applied torque with different lubricants in the threads to achieve specific clamp loads. Doesn't even require a deep dive into fastener install torque to find one. Lock-Tite and similar thread lockers are not, IME, specifically mentioned on those charts since a thread locker is not classed as a thread lubricant.
However, my Lock-tite Design Manual (96/97 ed.) lists some K factor values on page 54. It doesn't list a lot of them and it doesn't list specifically those alloys used in firearms, but these will give y'all some idea:
Note that these values are based on the fasteners not being degreased before the application of the thread locker. Unfortunately, the values given for degreased first are even fewer:
(I have not listed all of the values in the chart since those omitted don't apply to firearms.)
Recall the basic formula for Torque T = KDF, where:
T = Torque
K = lubrication adjusting factor listed above
D = Nominal bolt or screw diameter
F = Clamp Force
A deeper dive will find info on also including the tensile strength of the parts in the assembly, but if you know what the mfg's torque spec is then it's just a little math to compensate for the thread locker.
However, my Lock-tite Design Manual (96/97 ed.) lists some K factor values on page 54. It doesn't list a lot of them and it doesn't list specifically those alloys used in firearms, but these will give y'all some idea:
Material | Oiled | Thread Locker |
Steel | 0.15 | 0.14 |
Phosphate (Close to Parkerizing) | 0.13 | 0.11 |
Cadmium | 0.14 | 0.13 |
Zinc | 0.18 | 0.16 |
404 Stainless | 0.22 | 0.17 |
T-6262 | 0.17 | 0.29 |
Material | Dry | Thread Locker |
Steel | 0.20 | 0.20 |
Phosphate (Close to Parkerizing) | 0.24 | 0.14 |
Zinc | 0.17 | 0.15 |
Recall the basic formula for Torque T = KDF, where:
T = Torque
K = lubrication adjusting factor listed above
D = Nominal bolt or screw diameter
F = Clamp Force
A deeper dive will find info on also including the tensile strength of the parts in the assembly, but if you know what the mfg's torque spec is then it's just a little math to compensate for the thread locker.