7 Best Milling Machines | March 2017
- includes detailed instructions
- minute dial increments for accuracy
- only two spindle speed options
- runs on standard 120v power
- 10-thread-per-inch leadscrew
- outperforms its size
|Model||PM-25MV (Without Stand)|
- 13-inch distance to spindle
- stand included in purchase
- 2-speed gearbox
- easy-to-read depth gauge
- cast-iron support column
- two-year warranty
A Brief History Of Milling Machines
It is believed that milling machines date back to the 1700s, although it is unclear as to by whom or when they were first invented. They are very similar to lathes, so the earliest models were most likely just variations on the typical lathe machine. Milling machines became a separate class of tools sometime between 1814 and 1818.
Most historians cite Eli Whitney as the first person to construct a reliable milling machine. His creation served as the prototype on which many later developers based their designs. Whitney's machine was created out of his need to be able to do produce guns quicker. In 1798 he was contracted by the federal government to manufacture a large number of muskets, but at the time, all guns were handcrafted and had no interchangeable parts. To remedy this problem, he created a semi-automated factory, which included a milling machine, that was capable of producing muskets quicker.
In 1867, a universal milling machine was displayed at the Paris Exhibition. It was created by Joseph R. Brown, who needed a way to produce spiral flutes for twist drills. His invention proved to be incredibly versatile, and he later added a formed cutter. Since that time, milling machines have been one of the most used industrial machining tools. They are extremely adaptable to a range of jobs, including cutting grooves, shoulders, flat and incline shoulders, as well as slots and dovetails.
In 1954, the milling machine became the first machining tool to be controlled numerically. This is a way to automate machine controls using precisely programmed commands. Before numerical control, all machine tools were operated by hand, which made them less precise.
How Milling Machines Work
Milling machines can be used on wood, metal, and nearly any other solid object to cut a range of shapes and sizes. They are most often automated by computer numeric control to carve out designs created in a computer-aided design program (CAD), but manually operated machines are also still common. Milling machines can be used in both horizontal and vertical orientations and many can perform multi-axis machining. Unlike many other machining tools, milling machines are capable of dynamic movement, which means both the workpiece and the tool can be moved during operation. This is one of the factors that makes them such a versatile tool.
The tool head of a milling machine can be swapped out for a number of different types, depending on what needs to be accomplished. Some common tool heads include ball end mills, rounding mills, fluted mills, and standard cutters. Those that are controlled by CNC are instructed by the computer when it is time to swap out their head for another milling tool, and are capable of doing it autonomously.
In addition to the desired shape of the cut, the correct milling tool is also determined by the material being worked. As wood has different properties than steel or plastic, it requires a different type of milling tool for efficient cutting. If the wrong milling tool is used, it may damage the workpiece, the tool, or even the milling machine itself.
The most basic tool used on a milling machine is a cutter. This is a specially shaped bar with saw teeth carved into it. The cutter head is rotated rapidly, allowing it to cut smoothly into the material being worked. The saw teeth of a cutter can be sized, spaced, and oriented in a number of ways to achieve the desired cut. For denser materials, straight teeth are better, while helical teeth work better for softer materials.
Choosing A Horizontal Or Vertical Milling Machine
When choosing a milling machine, there are a few different factors that must be considered. The first step is deciding if you need a vertical or horizontal cutter. Vertical mills are the newer form of milling machines and use a die-sinking method. They cut using vertical planes and come in three basic sub-categories; bed mills, turret mills, and mill-drills.
Bed mills use a stationary spindle and have a table that can only move in a perpendicular motion to the spindle. This somewhat limits their design capabilities, but they are generally cheaper, making them a good choice for someone who does not need parallel cutting capabilities.
Turret mills are often considered as superior to bed mills as the table can move both perpendicular and parallel to the spindle. They are usually best as smaller machines because the quill used to raise and lower the cutter is often difficult to reach on any size machine, and extremely heavy on larger models.
Mill-drills are the most commonly found milling machines in home and hobby shop use. They are smaller, lighter, and more affordable than other types of milling machines, but aren't suitable for large volume work.
For those with very long projects, horizontal mills are often a better choice. As you might imagine, they use a horizontal tool to cut material. They excel at creating bezels, grooves, and spirals. They are also better for those working on multi-sided pieces. For those that need a truly versatile machine, one that features a rotating head and is capable of both horizontal and vertical cutting is best.