Boring Tools Information


Description: is a mass-reducing process of enlarging a hole that has already been drilled or cast. The process is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole. Boring tools have many different uses but all accomplish the same three basic tasks:


  • Bring holes to the proper size and finish.
  • Straighten original drilled or cored holes and correct defects in casting.
  • Make the holes concentric with the outside diameter.


Automated Boring Machines

Automated boring machines are operated and powered by motors and machinery. In addition to type, industrial buyers should consider application, precision, power, cost and time requirements for the job.


Video on drilling and boring.


Automated Machine Type

Precision Boring is a single-point cutting operation. The workpiece moves parallel to the axis of rotation of the cutting tool and enlarges an existing opening in a workpiece, producing a precise internal cylindrical surface. Precision boring can also be used to straighten and enlarge existing holes by advancing the workpiece into a rotating single-point. The material is removed as small chips. Precision boring machines are available in a wide range of sizes and types.


Description: Precision Machining

Image Credit: Precision Boring Company


Jig Boring produces a precise internal cylindrical surface by enlarging an existing opening in a workpiece. The single-edge cutter is advanced parallel to the axis of the hole and rotated inside a stationary workpiece. The machine has a bade, precision work table, column, and spindle housing. The spindle and work table are used for positioning and have a high level of accuracy. Jig boring machines use rigid, solid boring bars to create deep holes and single point tool bits for creating small holes. Other tools include adjustable insert boring bars, and offset heads. The tolerance and surface finish depend upon tool geometry, environmental conditions and the alignment of machine components and fixtures. The rigidity of the system, along with the cutting speed, fluid and chip removal, can also have an effect on the system. Cutting fluid needs to be used with a jig boring machine to keep the tool cool and reduce wear. Cutting fluid also allows for higher cutting speeds and feed rates.


Lathe Boring is used to produce conical and cylindrical surfaces. The single-point cutting tool enlarges an existing opening in a workpiece by moving parallel to the axis of rotation.  To produce a taper on the workpiece, the cutting tool moves at an angle to the axis of rotation. The workpiece is held in a chuck and rotated as a boring bar with an insert attached to the tip of the bar is fed into an existing hole. When the tool comes into contact with the workpiece a chip is formed that may be continuous or segmented, and the surface produced is called a bore.  This process does not require any special set equipment, except the boring bar. Tools are available in a wide range of sizes and shapes for use in different applications. There are several factors that can affect the results of the processing, including tool geometry, cutting speed and feed rate, rigidity of tool, workpiece, and machine, and the chip removal. Also important are the environmental conditions and the alignment of the machine components and fixtures.


Design Tip: Avoid boring holes that have a flat bottom because of the possibility of damaging the end of the boring bar. Also, interrupted cuts are difficult to perform with accuracy, so cuts should be uninterrupted when possible.


This video shows a simple boring operation.

Video Credit: Virtual Machine Shop


Vertical Boring is used to produce an accurate internal cylindrical or conical surface by enlarging an existing opening. The large workpieces rotate about a vertical axis as the single-point cutting operation is fed into the work. The tool advances vertically and horizontally in order to control the depth and diameter of the cut produced. The bore hole is always concentric with the axis of rotation of the work piece. The machine for vertical boring is similar to lathe boring and consists of a base, a rotating horizontal work table, a column, and a cross rail. The cross rail supports one or more tool heads. Tolerance and surface finish for vertical boring depends on the tool geometry, cutting speed and feed rate. The rigidity of the tool, workpiece and machine, as well as system for chip removal can also have an effect on the process results.



Vertical Boring Machine. Image Credit


Horizontal Boring uses a single-point cutting tool to create accurate internal cylindrical surface by enlarging an existing opening in a workpiece.  The machine has tool motion parallel to the axis of rotation. Holes are created by advancing one or more rotating single-point cutters horizontally into a medium to large stationary workpiece. Material chips are formed as the workpiece is advanced and helical internal feed marks are left. Horizontal boring machines can be used for milling, drilling, reaming and tapping, which saves setup time when changing application. They are designed for heavy workpieces and have a rotating worktable which can feed horizontally, parallel, and at right angles to the spindle axis.


There are four styles of horizontal boring machines including:


  • Table type, which is also known as the universal type. It is the most versatile horizontal boring machine.
  • Planer type
  • Floor type
  • Multiple spindle




Tool Material



Precision Boring

Produce a precise internal cylindrical surface by enlarging an existing opening in a workpiece.

Carbide, ceramic and diamond tools

Accurate finishing on internal bearing surfaces for part production, turning facing, grooving, chamfering and contouring.

+/-0.0001 in.

Lathe Boring

Produce conical and cylindrical surfaces

High Speed steel, brazed carbide, carbide or ceramics

Straight holes, tapered holes, holes with several diameters

+/- 0.002 in. for deep holes. +/-0.0005in. for shallow holes

Vertical Boring

produce an accurate internal cylindrical or conical surface by enlarging an existing opening

High speed steel, carbides, ceramics, or diamonds

Small length-to-diameter ratio. The workpiece is often very large and cannot be rotated on a horizontal axis.

+/-0.005 in. for most.

+/-0.002 for precision

Jig Boring

Produces holes with highly precise dimensions and locations

High speed steel, carbides, ceramics, diamonds

High level of dimensional accuracy such as jigs, tools, and fixtures.

+/-0.001 in. for diameter and +/-0.003 in. for depth. For precision applications +/-0.002 in. for diameter, +/-0.005 in. for depth

Horizontal Boring          

Produce an accurate cylindrical surface by enlarging an existing opening


Large work pieces



To ensure proper functionality, several calculations should be completed. These include power requirements, system requirements, cost estimates and time of process.

Boring Process

Boring Process. Image Credit: CustomPartNet


Power is calculated using unit power and material removal rate: 

Machine hp = unit power x removal rate (in3 / min)

Unit power is based on high speed steel (HSS) and carbide tools, with a feed of .005 inches per revolution (ipr) to 0.020 ipr and 80% efficiency.   



Hardness (HB)     

Unit Power





50- 145




Cast Iron





Mild Steel





Stainless Steel





System Requirements

Specifications including cutting speed and removal rate should be considered when selecting an automated boring machine.


Cutting Speed:

SFM = D x 0.26 x RPM

Feed per Tooth:


Spindle Speed:

RPM = SFM x 3.82 ÷ D

Table Feed:


Inch (Feed) per Revolution:


Metal Removal cubic in/min:




Diameter of Tool.


Number of Flutes.


Feed per Revolution.


Table Feed.


Inch per Revolution.


Feed per Tooth.


Cutting Speed.


Spindle Speed.


Axial depth-of-cut (Length).


Actual Horsepower available at running RPM.


Power constants for HP (HP/CI-MR).


Radial depth-of-cut (Width).


Metal Removal Rate (Cubic inches per minute).

There are several online calculators available to aid in these calculations.


Cost Estimates


Determining cost can be done by considering several factors including:


  • Setup time
  • Load/unload time
  • Idle time
  • Cutting time
  • Tool changing time
  • Tool costs
  • Direct labor rate
  • Overhead rate


Time of Process


Time is closely related to cost. When calculating the length of time the boring process will take, the speed, feed rate, retract rate and length of cut are the major variables to consider.

Boring Time = L/F

Retract Time = L/R


F= Feed rate (ipr)
R= Retract rate (inches per minute- ipm)
L= Length of cut (in.)


Handheld Boring Tools

Handheld tools are used for working on wood or metals and use a variety of bits to determine the size and shape of the holes drilled in the material.Description:


  • Drills bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole.


    • Braces are used to drill holes in wood. Pressure is applied to the top and the tool is rotated with a U-shaped grip.
    • Gimlets are used to drill small holes in wood so that it does not splinter
    • Push drills use a spiral ratchet mechanism for small applications.
    • Pin chucks are small hand-held drills for jewelers.

  • Punch and chisel sets typically includes a set of tools such as pin punches, taper punches, center punches, chisels with varying sizes of blades, and a chisel punch gauge.

  • Awl refers to a number of tools which feature a sharp, metal blade, often a rod with a sharp tip. There are many styles for their wide use in industry and trade. These are a few of the types of awls available:


    • Bradawl or Pricker awl has a beveled tip and is used to make pilot holes in wood for brads and screws.
    • Bridle Awl or Harness Awl is used to make holes in leather prior to stitching. It has a diamond-shaped point and comes with a range of diameters to suit the work.
    • Scratch Awl, Clicker's Awl, or Joiner's Awl is a woodworking tool used to mark wood for nails and screws. The point is tapered and usually round, though there are also reaming blades offered.
    • Scribe, Scriber, or Scribe Awl are used to make guide marks for sawing, signwriting, metal fabrication, and textile marking.

  • Auger Bit is a tool that bores holes through wood, metal, rock, concrete, soil or ice. The spade bit and paddle bits are the most common and have wide, flat cutting surfaces. Auger bits can be hand or electrically powered. They are rated to drill through a specific material or surface and should only be used for the material they are rated for.


Auger Bit. Image Credit:   


  • Chisels are hand tools for a shaped cutting edge on its end for carving or cutting hard material. In industrial use, a hydraulic ram or falling weight drives the chisel into the material to be cut. Chisels come in a wide variety of shapes and materials for their specific application. Several types include:


    • Beveled Edged Bench Chisels:
    • Heavy Duty Beveled Edged Chisels:
    • Mortise Chisels
    • Paring Chisels


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