People are going to think I’m nuts but there actually is a proper way to sharpen a flat blade screwdriver.
Only watchmakers do this though, perhaps good gunsmiths too, but that seems to be because nobody else knows of this anymore.
If you are curious, the proper fit of a blade screwdriver should never touch the bottom of the screw slot. If your screwdriver is a perfect cylinder like a watchmaker’s screwdriver, it should only touch the top part of the slot and friction wedge in without touching the bottom of the slot. You can lightly radius the edges of the flat tip so that the outside of the screwdriver blade is only as wide as the screw you are removing so that the blade does not scratch any surrounding metal if it is sunk into metal like a watch bridge.
Grind a flat 180 degrees apart on both sides of the screwdriver tapering to just slightly smaller than the screw slot, general rule of thumb if you are using the cylinder as a guide, make the flats on either side about three times as long as the diameter of the screwdriver cylinder, when tapering to the slot size. For a 1mm diameter watchmakers screwdriver, I just trigged it- about 18.5 degrees a side.
If you do all this right you will get a screwdriver that is perfectly fit to a flat slot screw, even if the head is slightly rounded. The screwdriver should friction into the slot without touching the bottom and you can remove the screw without the slightest deformation of the screw.
That’s how watchmakers do it and that’s how I was trained to do it in watchmaking school.
We did it with files and hand sharpened every screwdriver. This is normally what is done when you get your watch fixed by someone competent.
There is an easier way that some watchmakers use and a beginner can use by getting a screwdriver rolling sharpening tool, and using a Norton India abrasive sharpening stone.
With practice it becomes very easy to do quickly for any screw.
