How to drill holes in Czech grid cable trays

Twist drills grab in thin material and drill three-lobed holes and can distort the material where you want it to be flat at the seal. 20mm is a bit small for a Greenlee style punch. Even a cheap one is better than nothing. What tools do I use to drill clean holes in both the plastic and aluminum enclosures so that the cable glands fit snugly without any gaps? I tried searching for M20. Whether you're cutting, drilling, or securing trays, having the best equipment boosts efficiency and safety. A rung spacing of 6 to 9 inches (150 to 230 mm) is preferable when the cable tray cont d for instrumentation and control applications that require. Drilling Holes for splice plates must be drilled in field-cut cable trays. [pdf]