Jig grinder
Encyclopedia
A jig grinder is a machine tool
used for grinding complex shapes and holes where the highest degrees of accuracy and finish are required.
The jig grinder is very similar to a jig borer
, in that the table positioning and spindles are very accurate (far more so than a manual milling machine or lathe). It is almost exclusively used by tool and die makers in the creation of jigs or mating holes and pegs on dies. There are usually many peripheral elements to a large jig grinder, including separate hydraulic motors, air compressors, and various cooling systems for both the hydraulic circuit and supplying coolant to the work and machine itself.
The machine operates by a high speed air spindle rotating a grinding bit. The air spindles are removable and interchangeable to achieve varying surface speeds. Some spindles are fixed speed (60000 rpm), others are adjustable (30000-50000 rpm), and still others are very high speed (175000 rpm). The machines have a standard X-Y table with the notable exception of knee travel. All axes are indexed to .0001" via a vernier scale on the handwheels, with higher accuracy available with the use of measuring bars. The machine head has two vertical travels, one rough head adjustment and the other a precise spindle adjustment. The spindle to which the detachable air spindle mounts also rotates at a variable speed and can typically outfeed .100" while running, again with an accuracy of .0001" on the handwheel or greater, for very precise hole, peg and surface grinding. A well-kept jig grinder will reliably position work to a higher degree of accuracy than is possible with handwheels alone. These features are all critical in positioning a hole and peg system a precise distance from a reference surface or edge.
The most important factor on a jig grinder is the dual-spindle configuration. The main spindle is roughly positioned with between 1" or 2" of travel for setup, and then the .100" of outfeed is used during machine operation to outfeed into the work. A spacer bar may be used between the grinder and main spindle, allowing large (9" radius or larger) work to be completed. The main spindle has a wide range of speeds to ensure proper grinder feed rates are maintained.
Machine tool
A machine tool is a machine, typically powered other than by human muscle , used to make manufactured parts in various ways that include cutting or certain other kinds of deformation...
used for grinding complex shapes and holes where the highest degrees of accuracy and finish are required.
The jig grinder is very similar to a jig borer
Jig borer
The jig borer is a type of machine tool invented at the end of World War I to make possible the quick-yet-very-precise location of hole centers. It was invented independently in the United States and Switzerland...
, in that the table positioning and spindles are very accurate (far more so than a manual milling machine or lathe). It is almost exclusively used by tool and die makers in the creation of jigs or mating holes and pegs on dies. There are usually many peripheral elements to a large jig grinder, including separate hydraulic motors, air compressors, and various cooling systems for both the hydraulic circuit and supplying coolant to the work and machine itself.
The machine operates by a high speed air spindle rotating a grinding bit. The air spindles are removable and interchangeable to achieve varying surface speeds. Some spindles are fixed speed (60000 rpm), others are adjustable (30000-50000 rpm), and still others are very high speed (175000 rpm). The machines have a standard X-Y table with the notable exception of knee travel. All axes are indexed to .0001" via a vernier scale on the handwheels, with higher accuracy available with the use of measuring bars. The machine head has two vertical travels, one rough head adjustment and the other a precise spindle adjustment. The spindle to which the detachable air spindle mounts also rotates at a variable speed and can typically outfeed .100" while running, again with an accuracy of .0001" on the handwheel or greater, for very precise hole, peg and surface grinding. A well-kept jig grinder will reliably position work to a higher degree of accuracy than is possible with handwheels alone. These features are all critical in positioning a hole and peg system a precise distance from a reference surface or edge.
The most important factor on a jig grinder is the dual-spindle configuration. The main spindle is roughly positioned with between 1" or 2" of travel for setup, and then the .100" of outfeed is used during machine operation to outfeed into the work. A spacer bar may be used between the grinder and main spindle, allowing large (9" radius or larger) work to be completed. The main spindle has a wide range of speeds to ensure proper grinder feed rates are maintained.
See also
- Angle grinderAngle grinderAn angle grinder, also known as a side or disc grinder, is a handheld power tool used for cutting, grinding and polishing.Angle grinders can be powered by an electric motor, petrol engine or compressed air. The motor drives a geared head at a right-angle on which is mounted an abrasive disc or a...
- Bench grinderBench grinderA bench grinder is a type of benchtop grinding machine used to drive abrasive wheels. A pedestal grinder is a larger version of a bench grinder that is mounted on a pedestal, which is bolted to the floor...
- Cylindrical grinderCylindrical grinderThe cylindrical grinder is a type of grinding machine used to shape the outside of an object. The cylindrical grinder can work on a variety of shapes, however the object must have a central axis of rotation...
- Flick grinderFlick grinderA flick grinder is a rough and ready surface grinder or tool and cutter grinder, its usage is varied but it may be used where great accuracy is not required, but a machine better than a bench grinder is required....
- Tool and Cutter grinderTool and Cutter grinderA tool and cutter grinder is used to sharpen milling cutters and tool bits along with a host of other cutting tools.It is an extremely versatile machine used to perform a variety of grinding operations: surface, cylindrical, or complex shapes...
- Centerless grinder