This unique jig drills through the corner of the hex, making it ideal for drilling nuts as well as bolts. The design allows use on virtually any hex-head fastener up to 1 1/16" (27mm) hex: SAE, metric, even Whitworth! Requires a 1/16" Drill Bit (Part No. 3746), sold separately. Not for use on reduced-hex nuts such as MS21042 Jetnuts.
The hex size of a nut must be 1/8" (3mm) larger than the thread size to avoid drilling through the threads. Despite this warning, the second photo shows a 3AN steel tube nut (Part No. 3235-03 STL) with 0.032 safety wire installed. The 7/16" hex is only 1/16" larger than 3/8-24 thread. There is breakout on the ID but when the tube sleeve is installed, it blocks less than half the diameter of the safety wire hole. 0.020 or 0.025 safety wire would normally be used on this small tube nut, but we used 0.032 wire just to demonstrate that the jig can be successfully used on tube nuts of this size. Note that we drilled near the top of the nut to avoid damaging the threads.
Tech Tip: Use a drill press and advance the bit VERY SLOWLY. Also use a good quality cutting fluid (do not use motor oil) and clear the chips from the drill bit frequently. If the tool or the nut begins to get hot, stop and clear the chips from the drill bit and from the top of the tool and add a fresh drop of cutting fluid before continuing. Trying to use this drill jig with a handheld drill will likely result in many broken drill bits and a great deal of frustration!
Note: As shown in the photo, we use a small piece of soft copper, brass or aluminum to protect the nut from being marred by the clamp screw. This is not included with the drill jig.
