What tool is suggested for sharpening the cutting edge of hot cut chisels?

The suggested tool for sharpening the cutting edge of hot cut chisels is a file. Files are specifically designed to remove material slowly and precisely, which makes them ideal for refining the edge of chisels without compromising their integrity. They can effectively grind down the edge to achieve a sharp point, essential for cutting metal effectively during thermite welding.

Using a file allows for better control over the sharpening process, helping to maintain the correct angle and shape of the chisel's cutting edge. This is crucial because a well-maintained edge will not only enhance the performance of the chisel but will also ensure safety during its use. Other tools like a grinder, while capable of sharpening edges, may remove too much material or generate excessive heat, potentially damaging the temper of the hot cut chisel if not used with care. A stone could be too coarse for this particular application, and sandpaper is generally less effective for shaping and sharpening metal tools than a file.