bazuku
Well-known member
If you can figure out the square hole thing, I'd love to know.
For small square or flat sectioned holes, purchase a set of mini files at a '$' shop and grind or belt sand two sides off the square sectioned file. This leaves two rough and two smooth surfaces at right angles. Be sure not to break the tapered section. The resulting smooth sides can be rounded over to prevent binding in use. Don't completely triangulate the file as this will weaken it significantly, making it prone to bending or snapping (depending on quality). Unmodified square files will bind in the hole, making the squaring process next to impossible.
If the tapered section is maintained, quite small holes can be squared by approaching from both ends.