For a lightweight quad build, screws matter more than most people expect. The goal is not just to use the lightest hardware possible, but to use the smallest, strongest, and most appropriate screws for each part of the frame. In practice, that usually means picking screw size based on the part you are fastening, the amount of thread engagement you have, and whether the screw is going into aluminum standoffs, brass inserts, or directly into carbon fiber with a nut on the back.
For most racing quads, M2 and M3 are the common sizes. M3 is stronger and more forgiving, but M2 can save a little weight if the frame and electronics are designed for it. If your frame already uses M3 hardware, it is usually better to stay with M3 rather than trying to mix sizes just to save a few grams. The weight difference is often smaller than people think, and consistency makes maintenance easier.
Length is where a lot of builders go wrong. A screw that is too long can bottom out in a standoff, hit a motor winding, crush a stack component, or poke through and snag wires. A screw that is too short may only catch one or two threads and loosen over time. A good rule is to aim for enough engagement to feel secure without bottoming out. In aluminum, getting several full threads engaged is important. In plastic parts, use even more care because they strip easily. For carbon fiber plates with a nut, make sure the screw passes through cleanly without forcing the hole.
Material choice depends on the job. Steel screws are usually the best choice for structural spots because they are strong and resist stripping. Titanium is lighter, but it is not always worth the cost unless you are chasing every gram and understand the tradeoffs. Aluminum screws save some weight but are soft, so I would avoid them in high-stress areas. For a race quad, steel is still the safe default for arms, stack mounts, motor mounts, and anything that gets removed often.
Head style matters too. Button head screws are common because they are easy to work with and look clean. Socket head cap screws are stronger in the tool interface and can be better when you need a solid wrench bite in tight spaces. Low-profile heads help where clearance is tight, but don’t choose them if they reduce tool engagement too much. A stripped screw on a tiny quad is a lot more annoying than carrying a fraction of a gram extra.
Also pay attention to thread locking. On metal-to-metal joints, a small amount of medium-strength thread locker can keep vibration from loosening screws. Do not use it on plastic parts, soft mounts, or where the manufacturer says not to. Many flight stack screws loosen because they were installed dry into metal and never checked after the first few flights.
The easiest way to choose is to match the frame’s recommended hardware first, then only upgrade or lighten where it makes sense. For a lightweight build, I would rather use the correct steel screw in the correct length than chase the absolute lightest option and create problems later. If you want, I can also give you a part-by-part screw checklist for a typical 5-inch racing quad.
