Thread restoring files are used exclusively to clean up and restore damaged threads on bolts and screws.
What are the characteristics of chequering files?
Cross section
A chequering file (American spelling: ‘checkering’) is rectangular in cross section.
Profile and cut
It is slightly tapered in thickness towards the point. It is cut on both faces, but safe on both edges.
The cut on a chequering file is different to that of most other files. It is double cut, but the overcut runs parallel to the edges of the file, in vertical lines towards the tang. The upcut is at 90° to the overcut, making a square grid pattern on the file.
The grid-shaped teeth of chequering files, mounted on their flat, rectangular bodies, make them ideal for carving perfectly parallel grooves in wood or metal, or for jimping or serrating knife blades.
‘Jimping’ is the term used to describe the creation of notches on the back of the blade for improved grip.