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What is a mill file?

What is a mill file?

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A DIYer lining their mill file up so that they can work at a shallow angle to sharpen it Mill files are multipurpose saw files that are most commonly used for sharpening blades. For more information, see: How to sharpen blades with a file
A DIYer using a mill file to level off the tops of a rip cut saw's teeth They are also used to even out saw teeth at the beginning of the sharpening process. This has earned them the nickname ‘mill saw’ files.For more about sharpening saws, see: How to sharpen a hand saw with a file: step by step
Image showing the shape of a flat file They are similar in shape to flat and hand files, and therefore lend themselves well to tasks suited to them.See: What are hand and flat files?

What are the characteristics of a mill file?

Diagram of a rectangular cross section

Cross section

Mill files are rectangular in cross section but may have one or more curved edges.

Image of a mill file to show the shape of the outline

Profile and cut

They are generally slightly tapered in width, although blunt mill files do exist. They are single cut on both faces and edges.

A kitchen knife which lends its name to knife files The shape and cut of mill files mean that they are excellent for sharpening flat blade edges. Their slight taper allows the option for more control when sharpening smaller blade sections, and the fact that they are single cut creates a smooth, consistent edge on a blade.
A hook knife, which can be sharpened by a mill file with one or more curved edges Mill files with curved edges can also sharpen more exotic blades, such as hook knives, as the curved edge will fit inside the hooked section of the blade.
Image of a bastard cut mill file, othewise known as a mill bastard file

Coarseness

The most frequently found coarseness on a mill file is bastard cut. For this reason, they are also known as ‘mill bastard’ or ‘bastard’ files.

An indication of the range of lengths in which mill files are usually available

Size

Mill files are usually availabe in lengths from 100mm (4 inches) to 350mm (14 inches).

The American flag, representing American pattern files

Swiss or American pattern?

Mill files are American pattern files.