Boring Head – Mill

Boring is a machining process used to enlarge an existing hole to a precise diameter and surface finish. Boring can be performed on a variety of machines, including lathes, drill presses, and milling machines. In this article, we will focus on boring as it is done on a milling machine using a boring head.

A boring head with an R8 shank.

A boring head is a tool that is attached to the spindle of a milling machine. The head holds adjustable boring bars that can be moved in and out to adjust the diameter of the hole being bored. The boring bars are generally held in place with set screws and can be adjusted using a micrometer dial.

The first step in the boring process is to mount the workpiece securely on the milling machine’s table. The center of the hole should be centered under the spindle and aligned with the axis of rotation. A drill bit or other tool is then used to create a pilot hole.

Next, the boring head is attached to the milling machine’s spindle and the boring bars are inserted into the head. The boring bars are adjusted to the desired diameter using the micrometer dial.

Micrometer adjust on a boring head.

Once the boring head is properly set up, the milling machine’s spindle is turned on and the boring head is fed into the workpiece. The feed rate and cutting speed should be adjusted to match the material being bored and the desired surface finish. This is usually done by adjusting the quill feed rate.

As the boring head is fed into the workpiece, it removes material from the inside of the hole, creating a precise diameter and surface finish. The boring bars, feed, and speed can be adjusted as needed to maintain the desired diameter and surface finish.

Boring with a milling machine and a boring head offers several advantages over other methods of boring. First, it allows for precise control over the diameter and surface finish of the hole being bored. Second, it is a versatile process that can be used to bore holes of different sizes and shapes. Finally, it can be performed on a milling machine, which is a common piece of equipment found in many manufacturing facilities.