from The Century Dictionary and Cyclopedia
- n. A bolt with a thread and a square or hexagonal head.
Sorry, no etymologies found.
The Core is a machine-bolt, 4-1/2 in. long and 5/16 in. in diameter.
Wind 6 layers of No. 24 or 25 insulated copper wire around a 5/16 machine-bolt that is 2-1/2 in. long.