Few 1/4 -20 socket cap head screw with washers were tested for optimum torque.
QJR 117E Snap On torque wrench was used. I found that 40 lb in was enough.
Looked up recommended values on the web later:
Our Thorlab SS 1/4-20 screw kits are SS 18-8 as DRY 70 inch / lbs max, lubricated 60 inch / lbs max
These numbers will varie with washers, material it's going into and so on!
BLACK-OXIDE Alloy Steel Socket Head Cap Screws can go much higher value
| Thread Size |
1/4"-20 |
| Length |
1/4" |
| Thread Length |
Full |
| Additional Specifications |
Black-Oxide Alloy Steel |
| RoHS |
Compliant |
The standard among high-strength fasteners, these screws are stronger than Grade 8 steel screws. They have a minimum tensile strength of 170,000 psi. and a minimum Rockwell hardness of C37. Length is measured from under the head.
Inch screws have a Class 3A thread fit. They meet ASTM A574.
Black Oxide—Screws have been heat-treated for hardness, which results in a dark surface color.
The information in this 3-D model is provided for reference only. Details
We still do not know that what torque values we get best performance : minimum jiggel and drift etc.
After looking at these numbers I raise my recommendation to 50 inch / lbs on a std aplication.
Rana is next to calibrate his feelings and declare the right number.
Than Koji....and so on
Once we a number, than I buy more torque wrenches to fit it. |