When you are building a racing drone, screw tightness is one of those small details that makes a huge difference. The goal is not maximum force; the goal is secure, repeatable, and vibration-resistant assembly. On most carbon frames, you want screws snug enough that nothing moves, but not so tight that you deform the plates, damage the standoffs, or strip the threads in motors or nylon inserts. If a screw is biting into metal, you usually only need firm fingertip pressure with a small hex driver. If it is threading into soft aluminum or plastic, go even gentler.
A good habit is to tighten in stages. Bring the screw down until it touches, then add just a little more until it feels secure. If you feel the driver start to cam out, stop immediately. That usually means you are already close to over-tightening. For carbon fiber, especially on arm and stack mounts, check whether the plates are flexing as you tighten. If the plate bows, the screw is too tight or you may be missing a spacer or washer.
Motor screws deserve special attention. They should be long enough to hold firmly, but not so long that they touch the motor windings. That is a mistake people make early on, and it can kill a motor fast. Use thread locker on metal-to-metal hardware if the manufacturer recommends it, but do not use it on plastic parts or nylon lock nuts. A tiny amount is enough. You do not want glue everywhere, just enough to resist vibration.
After your first few flights, inspect every critical fastener again. Racing drones vibrate hard, and a build that feels perfect on the bench can still loosen over time. Check motor screws, stack hardware, arm bolts, and prop nuts before every session if you can. It only takes a couple of minutes and can save you from a crash.
If you are unsure, compare the screw feel across the frame. The right tightness often feels consistent: firm, seated, and stable, but never forced. With experience, your hands will learn the difference. Until then, it is better to be slightly under-tight and recheck than to over-tighten and damage an expensive part.
