Bridgeport Heidenhain CNC Mill
Programming & Operating Instructions
The ETSU Department of Technology's Bridgeport/Heidenhain Computerized Numerical Control (CNC) mill consists of a modified Bridgeport Series I vertical mill fitted with a Heidenhain model TNC 155 closed-loop 3-axis CNC Controller. (The 155 model is the same as the 154 model, but has no graphics. Also, the TNC 155 Parameter data appearently is quite similar to the Bridgeport Series 1 Interact 151B parameter data.) The table, saddle, and quill axes are fitted with zero-backlash ball screws and servo motors with rotary resolvers.
The Bridgeport/Heidenhain CNC's many features include:
- It can be programmed either in Heidenhain's "conversational" format (which
doesn't use G-codes) or in the traditional RS-274-D (ISO) word address G-code format.
- The controller has two registers: one for entering or editing a program and another for
running a program. Thus one program can be run while another is being entered or edited.
- Its range of axis motion is: X=18.0 Y=11.9 Z=4.9 inches.
- It has a 2 HP motor, with about 80% (1.6 HP) available at the spindle.
- The origin can be established anywhere desired and moved to another location whenever
- It can execute loops and macrosor subroutinesnested up to 8 levels deep.
- It can operate in either the incremental positioning mode or absolute positioning mode
you can go back-and-forth between these modes. It defaults to absolute mode.
- It can cut angular paths (linear interpolation) in the X-Y, X-Z, Y-Z, and X-Y-Z planes.
- It can cut circular paths (circular interpolation) in the X-Y, X-Z and Y-Z planes and
perform thread milling (helical interpolation).
- It can operate in either metric or inch units.
- It has canned X-Y axis cycles for circular pocket and rectangular pocket milling.
- It has canned Z-axis cycles for drilling, peck drilling, boring, and countersinking,
counterboring, or spotfacing.
- It can be programmed in either Cartesian (X-Y-Z) or polar coordinates.
- Will accept tool length offsets (TLOs) thru either numerical data or by digitizing.
- Geometry can be rotated about the origin to any desired angle.
- It can scale a part up or downmake it larger or smaller.
- It has cutter compensation capability to permit the use of undersize or oversize
- It can store 3100 blocks or 32 programs; no program can contain >1000 blocks.
The Heidenhain controller can be programmed in either of two formats:
- the ISO format--otherwise called the RS-274-D, EIA-274, or G-Code format; and
- the "conversational" format, a somewhat more intuitive and flexible format
than the ISO format but more sensitive to spelling and other syntax errors from off-line
programming. Therefore, the ISO format will be explained herein.
The following chapters list most of the factors that you must consider when writing a
program for the Bridgeport/Heidenhain Mill. They will show you step-by-step procedures for
utilizing loops, macros, canned cycles, circular interpolation, and tool length offsets
(TLOs). Instructions are also given for manual data input (MDI) and program input and
output via the computer.