Selecting the right end mill

A common theme so far has been that the end mill should be as sharp as possible. While they certainly wear differently depending on what and how they are made as well as what materials they have been used with and at what speeds, you should still consider your bits as consumables. Most kit-built 3018 machines will come with a handful of end mills (some as few as two and at least one kit I built had none). You should also consider different collets to accommodate the various end mills. A collet is the flange or sleeve that you insert into the spindle end that holds the end mill in place. On a common hand drill, this translates to the chuck, which you tighten by hand with a key. Other machines that use collets include Dremel tools. Here’s a picture of some collets that came with my spindle; note how the hole diameters differ. This allows you to use different bits in your machine:

Figure 3.2 – Sample collets

Different...