Locating Devices 107

This class identifies the most common types of locating components used in custom workholding devices and fixtures.

Class Details

Class Name:
Locating Devices 107
Number of Lessons:
Additional Language:
Spanish, Chinese

Class Outline

  • Objectives
  • The Purpose of Workholding Devices
  • The Purpose of Locators
  • Locator Tolerance
  • Basic Types of Locators
  • Fixed vs. Adjustable Locators
  • V-Locators
  • Locating Nests
  • External Locating Pins
  • Internal Locating Pins
  • Locating Pin Setups
  • Types of Adjustable Locators
  • Types of Indexing Devices
  • Summary


  • Describe the role of a workholding device.
  • Describe the role of a locator.
  • Describe locator tolerance.
  • Identify the two basic types of locators.
  • Distinguish between adjustable and fixed locators.
  • Identify uses for a V-locator.
  • Describe the use of locating nests.
  • Describe external locating pins.
  • Describe internal locating pins.
  • Describe common locating pin setups.
  • Describe adjustable locators.
  • Describe types of indexing devices.

Job Roles


  • CNC Milling Programming, Setup, & Operation
  • CNC Milling: Programming, Setup, and Operations-FastTrack
  • CNC Turning Programming, Setup, & Operation
  • CNC Turning: Programming, Setup, and Operations-FastTrack
  • Manual Milling Skills-FastTrack
  • Milling I
  • Turning Operations: Turning Between Centers-FastTrack
  • Turning Operations: Turning Chucking Skills
  • Turning Operations: Turning Chucking Skills-FastTrack


Vocabulary Term Definition
adjustable locator A locator that can be adjusted to accommodate variations in workpiece dimensions. Adjustable locators are less accurate than fixed locators.
alignment pin A pin that is used to lock a workpiece into position on an indexing jig. An operator pulls the alignment pin into and out of a hole that lines up with another hole in the workpiece.
assembled locator A separate locator device that is attached or fastened to the tool body of the workholding device. Assembled locators can be easily replaced if damaged.
cast Material that has been poured into a mold as a liquid and cooled into a solid form.
clamp A device that resists secondary cutting forces during a machining operation. Clamps are used to hold a workpiece against the locators.
cutting force A force that is generated by the cutting tool as it machines the workpiece. Cutting forces are divided into primary and secondary cutting forces.
external locating pin A locating pin that is used to locate an outer surface of a workpiece.
fixed locator A locator that is specifically designed to maintain a fixed position for a workpiece dimension.
horizontal plane An imaginary plane that is parallel to the ground floor. The top of a table is typically positioned on a horizontal plane.
indexing jig A jig that is specifically designed to locate a part in multiple positions, one after another. Indexing jigs are often used to drill holes around the surface of a cylindrical workpiece.
integral locator A locator that is built directly into the body of a workholding device.
internal locating pin A locating pin that is used to locate an interior hole of a workpiece.
locating nest A fixed locator that completely surrounds the dimensions of a workpiece. The workpiece rests within the locating nest.
locating pin An assembled locating device that can be used to locate either an outside workpiece surface or an interior hole. Locating pins are available in numerous shapes and sizes.
locator A device that resists primary cutting forces during a machining operation. Locators can be used to support a workpiece from below or locate it on a horizontal plane.
partial locating nest A locating nest that surrounds only portions of the workpiece surfaces.
primary cutting force A cutting force that is directly generated by motion of the cutting tool during machining. Primary cutting forces occur in the same direction as cutting tool movement.
production run The collective processes that are necessary to manufacture a group of similar or related parts.
redundant location The use of an extra, or duplicate locator that does not add to the accurate positioning and supporting of a workpiece surface. Redundant locators potentially introduce errors in workpiece tolerancing.
relieved locator A locating pin with a diamond-shaped head that is used to position a workpiece in only two opposite directions. Relieved locators are most often used with an internal locating pin.
rest button A short locating pin that is used to both support and locate a workpiece.
retractable plunger A spring-loaded device with a metal ball that is used to lock a workpiece into position on an indexing jig. The spring forces the round ball into a hole on the workpiece.
secondary cutting force A cutting force that is generated in response to primary cutting forces. Secondary cutting forces include vibration during machining and forces that attempt to lift a workpiece after a drill penetrates the workpiece.
shoulder A ring or collar on a locating pin that enables the pin to withstand greater loads. Shoulders can also be used to support a workpiece.
spring locating pin An adjustable locator with a metal or plastic bulb that is used to push a workpiece up against fixed locators on the opposite side.
spring stop button An adjustable locator with a metal button or tang that pushes a workpiece up against fixed locators on the opposite side. Spring stop buttons exert more force than spring locating pins.
threaded adjustable locator An adjustable locator with a threaded knob that is turned to push up against the workpiece surface.
tolerance The unwanted but acceptable deviation from a desired dimension. Workholding devices must have a tighter tolerance than the desired tolerance of the workpiece.
tool body The foundation of a workholding device. The various components, such as locators and clamps, are fastened to the tool body to create a customized workholding device.
vise A workholding device with two jaws that grip and hold a workpiece in place. A vise is mostly used to hold rectangular or cubic workpieces with fairly simple dimensions.
V-locator A fixed locator that uses an angled interior to position and center the cylindrical surface of a workpiece.
workholding device A device used to locate and hold a workpiece. The workholding device references the tool performing the operation on the part being held.
workpiece A part that is being worked on. It may be subject to cutting, welding, forming, or other operations.