Allen key, also known as allen wrench is a basic driver which is used to tighten or loosen bolts and screws that have internal hexagonal recesses (sockets).
| Hex Size | Length of long arm | Length or short arm |
| 1/16 inch | 91 mm | 15 mm |
| 3/32 inch | 112 mm | 19 mm |
| 7/64 inch | 119 mm | 20 mm |
| 1/8 inch | 123 mm | 21 mm |
| 9/64 inch | 130 mm | 22 mm |
| 5/32 inch | 137 mm | 27 mm |
| 3/16 inch | 154 mm | 34 mm |
| 1/4 inch | 185 mm | 34 mm |
| 5/16 inch | 195 mm | 37 mm |
| 3/8 inch | 224 mm | 42 mm |
How to use
Take the allen key, and put its face into the screw that needs to be tightened or loosened. To tighten it, rotate the allen key clockwise till the point it becomes tight, and similarly to loosen it, rotate the allen key counter clockwise till it becomes loose and comes out.
Common applications
1. Tightening and loosening internal hex bolts.
Some example tasks that students can try out in the ATL Lab
1. Take some device with internal hexagonal socket, loosen the screw and then tighten it back using allen keys
Important Links
1. Uses of allen keys (https://youtu.be/sGu-eFH02Go)
