Socket head cap screws are actually on of my favorite fasteners. They can be found on a lot of “do it yourself” type projects. Because they are typically fastened with an allen key, they can be very precise. They are very easy to work and can be loosely fastened by hand. Metric and standard sizes are largely available in steel, and stainless steel. socket head cap screws made from brass are not common, and are used in very specific applications, like food processing.
Bicycles are usually covered in 5mm socket head cap screws. They make it very easy to install water bottle cages, and other components. A bicycle mechanic will usually own a few allen drive wrenches for this specific reason. I’ve seen them used as structural fasteners for small things like desktop 3D printers. One draw back for socket head cap screws is the size of the head. If you’re using one of these machine screws without a recessed hole, the head can really stick out
Stainless Steel Socket head Cap Screws
Stainless Steel Socket Head Cap Screws are great for outdoor applications. Stainless steel is rust resistant and works well on fresh water boats, model aircraft, and remote controlled drones. When building anything that will be spending a prolonged time outdoors, you should think stainless steel. Due to the large head of the socket head cap screw, it has a some resistance to stripping.
Where to buy Socket Head Cap Screws
Socket head cap screws are available at many hardware stores. They are not the most common but a lot of places to stock the more common standard sizes. Small metric socket head cap screw are best found on the Internet through online sellers. They are more common at hobby stores too, because of their common use in remote controlled aircraft and cars. Socket head caps screws in Canada are also available through online retailers