How to Select Fixed Gages

Fixed gages are designed to access a specific attribute based on comparative gaging.  These gages are used for quickly assessing approximate size in a go / no-go manner.  They are available in English or metric configurations.

Types of Fixed Gages

The most common types of fixed gages are detailed below. They differ based on the type of measurement or comparison being made.

• Angle gages have a series of fixed angles for comparative assessment of the angle between two surfaces.
• Center gages are fixed with a v-shaped notch for finding the center of a part or bar with a round or square cross-section.
• Drill gages are fixed with a series of precise holes used to gage drill diameter size.
• Gear tooth gages are fixed gages used for determining diametrical pitch of involute gears.
• Pipe and tube gages have a fixed design to quickly access pipe, tube, or hose features such as outer diameter, inner diameter, taper, or tube bead.
• Radius, fillet, or ball gages are used for comparatively determining the diameter or radius of a fillet, radius, or ball.
• Screw and thread pitch gages are serrated to comparatively assess thread or screw pitch and type.
• Taper gages consist of a series of strips that reduce in width along the gages length, and are used to gage the size of a hole or slot in a part.
• Thickness gages consist of a series of gage stock fashioned to a precise thickness for gaging purposes. Taper and thickness gages are often referred to as feller gages.
• U.S. standard gages have a series of open, key-shaped holes and are used to gage sheet or plate thickness.
• Weld gages are used for assessing weld fillet or bead size.
• Fixed wire gages have a series of open key-shaped holes and are used to gage wire diameter size.

Additional Devices

In addition to specific fixed gage types, there are two less focused-on device groupings or materials that may be used for this type of comparative gaging.  Gage stock is a material that is fashioned to a precise thickness for gaging purposes.  Gage stock is available in rolls or individual strips.  Gage sets and tool kits consist of several gages and accessories packaged together; often in the case with adjusting tools. Tool kits sometimes contain alternate extensions, contact tips, holders, bases, and standards.