- Jig grinder
A jig grinder is a
machine toolused 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.
Tool and Cutter grinder
Wikimedia Foundation. 2010.
Look at other dictionaries:
jig grinder — noun Etymology: jig (II) : a precision grinding machine with fine adjustments for work requiring great accuracy (as in the fabrication of jigs and dies) … Useful english dictionary
Jig (tool) — In metalworking and woodworking, a jig is a type of tool used to control the location and/or motion of another tool. A jig s primary purpose is to provide repeatability, accuracy, and interchangeability in the manufacturing of products. A jig… … Wikipedia
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. [Moltrecht, Karl Hans: Machine… … Wikipedia
Cylindrical grinder — The 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. This includes but is not limited to… … Wikipedia
Surface grinder — A surface grinder is a machine tool used to provide precision ground surfaces, either to a critical size or for the surface finish.The typical precision of a surface grinder depends on the type and usage, however +/ 0.002 mm (+/ 0.0001 ) should… … Wikipedia
Die grinder — A pneumatic die grinder with a right angle head. A die grinder is a handheld power tool used to grind, sand, hone, polish, or machine material, typically metal but also plastic or wood. They are usually pneumatically driven, although versions… … Wikipedia
Sharpening jig — A sharpening jig is often used when sharpening woodworking tools. Many of the tools used in woodworking have steel blades which are sharpened to a fine edge. A cutting edge is created on the blade at the point at which two surfaces of the blade… … Wikipedia
Tool and die maker — Not to be confused with tap and die. Tool and die makers are workers in the manufacturing industry who make jigs, fixtures, dies, molds, machine tools, cutting tools (such as milling cutters and form tools), gauges, and other tools used in… … Wikipedia
Milling machine — For the machine used in road construction, see Asphalt milling machine. Not to be confused with mill (grinding). Example of a bridge type CNC vertical milling center … Wikipedia
Grinding wheel — Grinding wheels A grinding wheel is an expendab … Wikipedia