Tips for Your Boring Operations

January 23, 2021 9:00 am

Boring is a cutting process used to enlarge an already existing hole in a piece of metal. The purpose of boring is to achieve accurate size holes and ultimately, satisfy tolerance expectations. This makes boring different from other hole making machining operations. Remember that the purpose of boring different from other hole making processes. Drilling is the development of an initial hole and reaming is solely done to smooth out the walls of an existing hole.

Choose the Right Application

Boring can be done with a lathe, mill or machines specific to boring like jig bores, boring machines, or boring mills.

One isn’t necessarily better than the other, it’s just about what you have access to. If you are looking for some educational materials about boring on a lathe, check out Turning and Boring by Franklin D Jones.

It is true that boring operations on a lathe are less complex and provide more flexibility than if you were to bore with a mill. There is a reason for that, and it comes down to the versatility of the boring tools that are used. More about that in the next section…

Choose Your Tools Wisely

When you can, spending good money on tools is the way to go. Investing in high quality will seldom steer you wrong. However, it isn’t always possible, and there are good tools on the market that are affordably priced.

It isn’t rare for chatter to occur during boring processes. A way to avoid this is by using boring bars and boring heads that are made from heavier materials, typically tungsten alloys. So, although the steel option may be more affordable, it won’t last you as long as a boring bar made from a heavier metal like carbide or tool steel.

Boring heads are recommended for applications involving larger holes where very tight tolerances are needed. They are specific to boring operations executed on a milling machine. When using a boring head, you don’t have much flexibility with hole size because the range is set in stone. If you want to adjust the hole size, you will have to change the boring head size. That means you will need an adjustable boring head. This makes boring applications on mills a bit more complicated than those on lathes.

Boring bars are used for both milling and lathe applications as they are placed in the boring head in milling operations. Deeper holes need a longer bore than a shallow hole, so the length of the boring bit you will use depends on the hole you’re working with. Shorter bits are positioned directly in the center of the boring head, whereas longer bits are positioned on either side of the head. At the tip of the boring bar is where you will see the cutting inserts in place. Boring bars can theoretically create any size hole as long as the bar fits in the hole, making them a more flexible option as you can achieve different size bores with the same bar.

The most common boring bars in machine shops have carbide tips as they are the most versatile and economical.

Check out some of these boring bar sets.

OSCARBIDE Indexable Boring Bars 8-Piece Set

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Consider this set if you are using either a boring machine or a lathe. The bar holders in this set are made of high-quality steel with tin coated, carbide inserts that protect against moisture and rust. The round shanks allow the operator to set positive or negative rake and the chip breaker eliminates long, stringy chips.

HFS (R) Boring Head R8 Shank Carbide Boring Bar Set

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For those who are doing boring operations on a mill, this particular set was designed so that the same bar can bore flat bottomed holes or faces. The bars are made from alloy steel shanks that were hardened and ground.

Accusize Industrial Tools 1/2″ 9-Piece Set

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This set is designed for lathe work. Each tool holder comes with a C6 tin coated carbide insert with a positive rake cutting angle and a built-in chip breaker. This set is great for general purpose cutting action. The set also includes a wrench, Allen key and extra insert screws.

Mophorn Indexable Boring Bars 16-piece Carbide Boring Head Tool Set

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This set is specifically for boring and CNC milling machine tools. This tool set includes 16 pieces of accessories including boring bars and hex wrenches. The set comes in a portable plastic toolbox that provides protection for all the pieces and keeps them clean and organized.

Measure the Bore

Even after the boring process is over, the job isn’t quite done. You will most definitely want to ensure that your bore is the correct size and meets the required tolerances. This can only be done by having the right tools. To learn more about the measuring process and the tools you will need, read Choosing the Right Bore Gauge.

For a sneak peek, here are some recommended measuring tools.

Mitutoyo 139-201, 1.5″ – 12″ X .001″ Tublar Inside Micrometer

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Fowler Full Warranty Extender Dial Bore Gage Set, 52-646-400, 1.4-6″ Measuring Range, 0.0005″

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Starrett 781XTZ-258 3-Point Contact 2-2 5/8-Inch Range

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Starrett S579GZ Self Centering Telescoping Gauge With 2 Telescoping Arms 

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