LOCATING PINS
Round Locating Pins can be used for both internal and external workpiece location in modular fixtures. For internal location, the diameter of the pin must match the size of the locating hole. These locators come in many standard sizes, and are readily available ground to special diameters. For external location, the size of the locating pin is not as critical. Here, a standard pin size strong enough to resist machining forces is the best choice.
Diamond Locating Pins are the most-common form of relieved locating pin used in workholders. To limit the pin's contact area, the diamond locating pin is made with four machined flats. The exact width of the contact area varies with the size of the pin, and is usually equal to one-third of the diameter on each side. Diamond pins are generally used as shown above. Here the diamond pin acts as a radial locator to restrict movement of the workpiece around the concentric locator, shown by the round-pin locator. The diamond pin is positioned to restrict the radial movement of the part. Since a diamond pin locates in only one axis, the contact areas of the pin must be positioned as shown. Positioning the pin any other way would allow the part to move about the concentric locator. Diamond pins are relieved to act only as radial locators, avoiding the redundant location that causes binding during loading.
Locating-Pin Adaptors are precision ground on top and bottom to provide accurate height location. Usually just one additional rest is required for full three-point system.
To mount a fixed Locating-Pin Adaptor between grid points, use a Multipurpose Extension Support. Alternatively, an Adjustable Locating-Pin Adaptor could be used for lower height (standard and heavy sizes only).
Three locating pins can be used in combination to locate workpieces with large internal diameters.
