Originally Posted by S10 Racer
Aircraft industry uses what is called a "micro stop". Not sure if that is what you're looking for though. It is for countersinking sheetmetal.
Micro stop is a countersinking tool and not a dimpling tool. To make a dimple tool you really need a countersink to make the die. To make the punch you can use a ball although it is not accurate to the angle of the screw head but will work in a pinch. Most sheetmetal screws either use a 90 degree countersink or a 100 degree countersink. Flat head allen screws have 82 degree heads. What you want to do is drill a hole into a piece of metal the size of the threaded portion of the screw. Then with a countersink, start opening the hole up until you get it to where the screw head fits into it and will sit flush on the top of the metal. Now you have to open it up larger to compensate for the thickness of the metal. For example, if your metal is .032 thick, you will need to go approximately .032 deeper with your countersink into the metal you are using as your die. Now you will need a steel ball of the appropriate side to get it to form out, OR.....you can grind the end of a punch down to the same angle of your countersink and use that. Your main problem will be aligning the top and bottom without using a pilot.