| adjacent |
The side next to the reference angle in a right triangle. The adjacent side cannot be the hypotenuse. |
| approach |
A small distance that the cutting tool travels before engaging the workpiece. The approach distance is added for safety reasons. |
| axes |
Imaginary lines that pass through the center of a point or object. Axes are used to describe the positions of objects on the Cartesian coordinate system. |
| CAD/CAM |
Computer-aided design/computer-aided manufacturing. CAD/CAM software helps programmers to efficiently design parts and generate part programs. |
| Cartesian coordinate system |
A system of numerically locating points in three-dimensional space. CNC machines use the Cartesian coordinate system to locate the tool tip and map the dimensions of a workpiece. |
| centerline |
An imaginary line that bisects an object into two equal halves. The centerline of a drill is used to divide its tip into two equal right triangles. |
| chamfering |
Machining an angled edge around the end of a cylindrical workpiece to remove sharp corners. Chamfering generally produces a 45° angle. |
| chuck |
A device that holds a workpiece in place as it rotates on a CNC lathe. A chuck commonly has three or four jaws that can be adjusted to fit variously sized parts. |
| circular interpolation |
The toolpath required to create a circular or partially circular part. Circular interpolation necessitates simultaneous movement on at least two axes. |
| CNC |
Computer numerical control. A computerized system used to control a mill, lathe, or turning center. CNC machines are much more precise than their manual counterparts. |
| CNC lathe |
A lathe that is controlled by a computer running programs driven by numerical data. CNC lathes are much more precise than their manual counterparts. |
| complementary |
Two angles that, when added together, measure exactly 90 degrees. For example, angles measuring 52° and 38° are complementary angles. |
| computer numerical control |
CNC. A computerized system used to control a mill, lathe, or turning center. Computer numerical control machines are much more precise than their manual counterparts. |
| cosine |
The ratio of the length of the side adjacent to the angle divided by the hypotenuse. Cosine is often written as cos. |
| diameter |
The measurement of a circle or cylinder at its widest point. The diameter of a drill can be used to find the length of its tip. |
| drill |
A fluted tool designed to drill holes. Drills used for CNC lathes typically have a 118° tip. |
| drilling |
A machining operation designed to create a circular hole in a workpiece. Drilling to the correct depth requires using trigonometry to calculate the length of the drill tip. |
| facing |
An operation in which an operator uses a lathe to feed a cutting tool across an end of a cylindrical workpiece to create a flat surface. Facing is usually completed before setting program zero. |
| full arcs |
A portion of a circle that forms an angle measuring exactly 90 degrees. Cutting full arcs requires circular interpolation. |
| G40 |
The G code to turn off tool nose radius compensation. G40 should be used for any part program in which G41 or G42 has been activated, either before a toolchange or at the end of the program. |
| G41 |
The G code to turn on tool nose radius compensation. G41 compensates to the left of the toolpath. |
| G42 |
A G code to turn on tool nose radius compensation. G42 compensates to the right of the toolpath. |
| hypotenuse |
In a right triangle, the side located opposite the right angle. The hypotenuse is always the longest side. |
| I and K method |
A method for programming circular interpolation that uses an I code and a K code to indicate the coordinate locations of the arc center. The I and K method cannot be used with the R method. |
| linear interpolation |
The toolpath required to create a straight line that does not travel parallel to any axis. Linear interpolation necessitates simultaneous movement on at least two axes. |
| offset |
In CNC programming, a mathematical, spatial value that compensates for a variable that would otherwise result in an improperly sized workpiece. Offsets for the lathe include tool nose radius compensation. |
| origin |
The fixed center point of the Cartesian coordinate system. The origin has a numerical value of zero for any axis. |
| part program |
Instructions used by a CNC machine to perform the necessary sequence of operations to machine a specific workpiece. Part programs are composed of G code. |
| partial arcs |
A portion of a machined circular part. Every partial arc measures less than 90 degrees. |
| perpendicular |
An object or plane that exists at a right angle to another object or plane. Three perpendicular axes are used to define the Cartesian coordinate system. |
| program zero |
A position that acts as the origin for the part program of each particular workpiece. Program zero is selected by the part programmer. |
| R method |
A method for programming circular interpolation that uses an R code to indicate the size of the radius that forms the arc. The R method cannot be used with the I and K method. |
| right triangles |
A triangle containing one right angle, which is an angle that measures exactly 90 degrees. Right triangles are useful for calculating tool positions. |
| shoulder |
On a workpiece with different diameters, the area where it transitions from one diameter to the other. Shoulders may be curved, requiring partial arc calculations. |
| sine |
The ratio of the length of the side opposite the angle divided by the hypotenuse. Sine is often written as sin. |
| symmetrical |
An object that is identical on each side of its centerline, or for which each half is a mirror image of the other. Symmetrical parts can be machined on lathes or turning centers. |
| tangent |
The ratio of the length of the side opposite the angle divided by the adjacent side. Tangent is often written as tan. |
| taper angle |
The degree at which a cylindrical part changes diameters along its length. Taper angles are used in programming calculations for turning tapered workpieces. |
| theoretical tool tip |
TTT. The location from which the CNC lathe calculates the position of the tool. The theoretical tool tip may or may not be located at the actual tip of the tool. |
| tool nose radius |
TNR. Describes the rounded tip of some tools. TNR must be compensated for with TNRC. |
| tool nose radius compensation |
TNRC. An offset feature that adjusts the toolpath to accommodate the rounded tip of an insert during contouring, chamfering, and other multi-axis operations. Tool nose radius compensation may be calculated either automatically by the lathe, turning center, or CAD/CAM software or manually by the part programmer. |
| toolpath |
A series of coordinate positions that determine the movement of a tool during a machining operation. Toolpaths are expressed in G code. |
| trigonometric ratios |
Mathematical ratios from which the sides or angles of a right triangle can be calculated. Trigonometric ratios are used often in CNC lathe programming. |
| trigonometry |
The branch of mathematics that addresses the measurements and relationships of a triangle and its parts. Trigonometry is used extensively in CNC machining. |
| turning centers |
CNC lathes that are also capable of milling operations. A turning center requires calculations in all three Cartesian axes. |
| X axis |
The linear axis representing the longest distance of travel perpendicular to the spindle. The X axis typically describes forward-and-away movement on the CNC lathe or turning center. |
| Y axis |
A linear axis that is rarely used on CNC lathes. The Y axis typically describes up-and-down travel on a turning center. |
| Z axis |
The linear axis that runs parallel to the spindle, or around which the spindle rotates. The Z axis typically describes right-to-left or left-to-right travel on the CNC lathe or turning center. |