Spade drills used for heavy duty hole creation are very different to normal twist drills. They comprise of two parts and deliver several advantages for in-situ machinists and for manufacturers carrying out repeat production runs.
The main advantage is that a spade drill includes a replaceable cutting blade. This is secured in a fluted holder which can be conveniently replaced when it reaches the end of its usable life. There are many other advantages too, but also a few drawbacks to be aware of.