Greetings. In my job, the most common fastener, by far, is the #12-24 under-cut flat head machine screw, usually made for #3 Phillips driver. Often, due to either poor manufacturing tolerances, and/or the use of poorly made "universal" type (12-24 near the head transitioning to wood thread near the tip) screws, the sheet metal framework that these screws are screwed into, become over-large (wallowed-out, we would say) and tend to strip when tightened. My solution has always been to tap for the next larger size (1/4-20). Is there a Metric machine size that would be slightly bigger than a #12 but smaller than 1/4" and have a pitch similar to 24TPI? Since the thickness of the tapped hole is rarely more than 3/32", the metric pitch would only have to be close to 24TPI, I would think. This way, I wouldn't need to tap for 1/4-20 and end up with an oversized head that doesn't counter-sink properly.

Solid body guitar. Mounting pickups to 3"x2" aluminum plates. Need to raise and lower those plates. Total travel .25". Plates need to be secure in all directions at all heights. Thinking two 'posts' per plate, one on each end with the adjusting mechanism accessible from back of guitar. Stainless T-nut (4) with set screws into back of body will work but question is what to I attach to the plates? Threaded insert and a spring? Ideas? Thanks ​​​​