Well... it does melt the (plastic) threads if you're too aggressive lol but if you're patient and allow the screw to cool it works good. I just thread a screw into a 2.6mm hole (no modeled threads) measure it with calipers and grind it until I hit the face of the jig. I find the side of my bench grinder works best since its flat.How does the jig fare? Id like to see it
Once I have the length right I thread it in a bit farther so I can put a chamfer on the end with a file.
The back side is flat.