Hand-Cutting and Fire-Hardening Steel Files Using Ancient Techniques

Metalworking Workshop
Hand-Cutting and Fire-Hardening Steel Files Using Ancient Techniques

After posting about Chris at Clickspring’s amazing series on reverse engineering the Antikythera Mechanism (the mechanical computer from antiquity), I have become obsessed with his channel. Such amazing content on all aspects of clockwork machining.

Some of the tools that Chris has made in reverse engineering the Antikythera Mechanism.

In addition to the Antikythera Mechanism videos that I posted about, he has two new “Ancient Tool Technology” videos that look at the ways in which the tools that constructed the mechanism might have been made.

The first video examines the metal files that would have been used in the construction of the Mechanism, especially in the likely hand-filing of all of the gear teeth. To create similar files, he uses mild steel (as a substitute for the wrought iron that the device’s makers likely would have used). Because mild steel is not hard enough to do the job of a file, Chris uses a technique of case hardening that would have been available to the ancients.

Chris has to make several bench tools to aid him in preparing and cutting the surfaces of the files. The first is a “stripping frame,’ a simple wooden holder that allows one to cut the file’s work surfaces while the workpiece freely turns to keep that its surface reasonably level with the file being used to “cut” the surface level. The next thing he makes is a file cutting workstation with file cutting anvil. Chris then makes a pair of file cutting chisels out of steel that are then case hardened using the same method he will eventually use to harden his homemade files. Once the file is secured on the cutting workstation, amazingly, he just eyeballs the teeth-cutting.

In this second video, Chris shows you how he case-hardened his files using common materials (salt, flour, leather-charcoal as the carbon source) that ancient metalsmiths would have used. He then adds water to make a paste, applies that paste around the files, encases them in clay vessels, and then places them in a fire. The longer they cook, the deeper the layer of high-carbon steel that’s produced.

The files being packed with carbon paste in preparation for firing.

Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.

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