marline spikes are often used as a lever for tension wire rope. They allow for a much tighter grip of the line instead of using the hand alone. They are also used as levers to open strands of laid rope. Other uses include drawing marline tight, untying knots and for splicing rope. Fabricated of iron or high-carbon steel, these tools are shaped in the form of a cone tapered with a flattened or rounded point. With its duck's bill taper on the end, it's also useful for digging into hemp made of tough knots. Those that are made out of tempered high-carbon steel, need to well-oiled for protection against rust. Most marline spikes range in size from six to 12 inches long, but may reach up to two feet or more for working heavy rodes and cables. Often, these tools can be purchased in sets with different sizes, and you can select different point styles like a squared off chisel point or a sharp pencil point. You can also purchase them as sets with rigging knives. Occasionally, people will refer to marline spikes as fids, but this is incorrect. Both fids and marline spikes serve the same purpose, but fids are actually carved and formed from ivory, bone or wood. In the age of sail and pirates, the marline hemp rope was not waxed but tarred. The only way to loosen tarred marline was to pick it free with an iron spike. The act of doing this was known as marling. Hence, the tool was eventually named the marline spike. The category of hammer keys includes hammer drills and rotary drills. With hammer keys, the hammering action delivers a short and rapid thrust to pulverize material. Some hammer keys are powered by batteries, and others are electrically powered. The more advanced power units utilize an electro-pneumatic hammering technology. With this technology, the hammer and the piston do not touch, but the air pressure in the chamber allows more efficient transfer of energy. These hammer drills are ideal for drilling holes in stone or masonry. They are also very effective on concrete. With its rapid hammering action, the hammer drill is much faster than a regular drill for brick or concrete. It delivers thousands of blows per minute. Although each blow is a low force, it's the thousands of blows per minute that enable it to pulverize through brick or concrete. While they are typically more expensive than conventional drills, they are preferable for applications like wood studs and concrete block. Rotary hammers are similar to hammer drills, as they pound the drill bit in and out while spinning. The difference is that rotary hammers used a piston mechanism rather they a clutch used in hammer drills. As a result, they deliver more power and can drill bigger holes a lot quicker. Hammer keys and marline spikes are just a few of the tools used by many industries, including the marine and construction industries. Without these modern tools, we'd just about be back in the cave age.