Bob's Shop Notes:
Toggle Switch Installation

Step 1 . . .

Tools needed: (1) A 15/32" spotfacer fitted with 1/8" drill bit as shown here (check with local supplier of machine shop tools. Click here for larger image.

(2) Modified #30 drill. Grind the end flat. Then grind a relief behind the cutting edges so that when the bit contacts the metal, only the cutting edges touch. Click here for larger image.

Step 2 . . .

Getting Started:Use a center punch and some careful layout to mark the centers of both a large hole to mount the switch and a location for a hole to engage the anti-rotation tab on the switch's anti-rotation washer. Use your spotfacer/drill to make a 15/32" switch mounting hole. Drill half way through and then turn workpiece over to finish hole from the other side. This CAN be done with a hand drill but a drill press will produce superior results. Unlike twist drills, a spot facer will open a nicely machined, almost burr-free hole with a minimum tendency to snag.

Step 3 . . .

Use a normal #30 drill to start a hole for the locking ring anti-rotation tab. Drill just deep enough to have the hole reach full diameter and then stop. Hole on the right in this picture is just barely full diameter and still has a conical bottom formed by a standard #30 drill.Click here for larger image.

Step 4 . . .

Use the modified drill to cut a flat bottom on the hole without penetrating the panel material. Sand or grind locking tab down to a total length of 0.020" to 0.030" from the panel surface.

The shallow blind hole and shortened locking tab will secure your switch without blemishing the face of your switch panel. This technique works best with panels of 0.050" thickness or more.

Questions or comments about this site? Click here to contact Bob at AeroElectric Connection