Bridgeport CNC Mill
 | This tool is currently broken, please contact the area host for more information. |
| Owner/Loaner | PS:One |
|---|---|
| Serial Number | {{{serial}}} |
| Make/Model | Bridgeport Interact Series I CNC milling machine |
| Arrival Date | 2014 |
| Usability | no |
| Contact | Dean Anderson, Elizabeth Koprucki |
| Where | Machine Shop |
| Authorization Needed | yes |
| Hackable | no |
| Estimated Value | ~$2000 |
| Host Area | {{{hostarea}}} |
Description
A Bridgeport Series I Interact milling machine with a Heidenhain TNC151 controller.
Capacity
Maximum table weight, centrally located: 300 pounds
X-axis travel: 18"
Y-axis travel: 12"
Z-axis travel: 5"
Knee travel: 14 3/8"
Positional accuracy: .0005"
Tooling
Kurt D60 vise
Approximately 13 NMTB 30 tool holders, some collet chucks (unidentified ER style), some with fixed bore.
1 NMTB 30 drill chuck.
Lubricants
The automatic lubrication system uses Vactra #2 oil. If the reservoir gets too low, a sensor will prevent the Power Enable switch from operating.
Maintenance
The Y and Z axis way wipers were replaced 4/28/15.
What works so far
Almost everything. The table and quill move as expected using the Heidenhain controller and joystick, but not the handwheel. We can create and run simple programs using the Heidenhain conversational programming mode. We have switched the machine over to ISO G-code, and have been able to run programs with this. We have changed the communication parameters to FE mode, which permits transferring programs to/from the machine's memory, as well as drip feeding programs directly.
We need to reassemble the machine and make many adjustments as well as establish a CAD/CAM process on a external computer.
The only big mechanical task remaining is to fix the bent ball screw cover.
The only big electrical task remaining is to repair/replace the handwheel.
Open Issues
Mechanical
The head has some unexpected noise. Not from the motor, probably from the Reeves drive. The Reeves drive needs to be adjusted.
Install the Kurt power draw bar and machine the draw bar to size.
X, Y and Z limit switches need to be adjusted.
Check the tension on the drive belts. Especially for the Y axis.
Y axis ball screw cover is bent and not sliding properly. It should be removed and replaced (or bent straight). Removal is difficult because it is bent. This could require removing the table, which is heavy.
Check the BP maintenance manual for other adjustments that are required.
Software
Find a process for backing up and restoring system parameters:
This requires a null modem connection from the Heidenhain's DB25 port to a DB9. We were using a DB9 to DB9 adapter that implements the null modem pin swaps. On the Heidenhain side of this, the DSR line must be connected and working! If it isn't, the TNC 151 refuses to think that the computer is present.
Parameters can be accessed by pressing MOD repeatedly until you are prompted to enter a Code, which is 95148. Care should be exercised with machine parameters. In this screen, pressing EXT then NO ENT causes a full dump to serial. Pressing EXT and ENT makes the machine look to read them, but sending them as an ASCII file via a terminal program doesn't seem to work.
Figure out how to drip code to the Heidenhain (Ed).
Set up the tool chain.
Electrical
Install a 3 phase 240v outlet near the machine. This machine is currently sharing one outlet with 4 other machines.
The machine was wired at the factory for 460 volt 3 phase and we use 230 volt 3 phase in our shop. Ed and Dean rewired the motor and controller box, in a temporary fashion, to use 230v. It is currently using a 460 to 230 volt transformer, which will eventually be removed.
Move the Heidenhain power source back to the Bridgeport control.
The Handwheel uses a Heidenhain HR 150.001 5000 F4 controller, Id.Nr. 220 954 01, S.Nr. 1300302 A. It is very fragile, using a glass encoder wheel. We have determined that the light bulb that illuminates the wheel, triggering a signal from the photocells, has burned out. This will either need replacement, or we will need a new encoder.
Purchase
Computer for design work and to drip G code to the Heidenhain. We already have a monitor.
Miscellaneous
Clean up the BP service manual scans and add the document to the wiki.
The TNC 151 can be programmed in Heidenhain conversational language, or G-code. By default, the keypad labels indicate their functions in conversational mode. In G-code mode, the keypad buttons take on different meanings. The controller originally came with a keypad overlay, attached by magnets, that had different labels for the buttons for use with G-code. We don't have this. Improvising something would be helpful.
Closed Issues
CMOS memory is used to store the machine parameters. the AA batteries that keep the memory alive leaked and caused minor damage to the battery carrier. We cleaned up the carrier and replaced the batteries. The parameters have been reloaded.
The spindle brake, spindle speed control and flood coolant system all are pneumatically driven and leaky. Maria Savrasova replaced the leaky fittings and tubing.
The original lubricating oil reservoir cracked. Todd Allen made a new reservoir out of acrylic using the laser cutter.
A machine screw was missing that held the ram to the column. It has been replaced.
A pneumatic line has been run from the shop air system to power the spindle brake, coolant and spindle speed control.
The mystery of the spindle taper has been solved. NMTB 30. We now have a good supply of tool holders.
the TNC 151 power supply failed while we were working on the machine. The problem was a bad 220uf 63 volt capacitor, which we replaced.
One half of a y axis limit switch failed. We swapped it for the other limit switch on the same axis which only needed one half working.
The homing sequence could not complete due to a bad index signal from the y axis rotary encoder. By adjusting the alignment of the encoder to the motor, the signal appeared. This adjustment may need attention in the future.
Reference
Tool Chain
The TNC 151 can be configured for Conversational mode or G-code. The former is designed to be simpler to view, understand, and for a machinist to key in from the control panel. The controller apparently can translate programs between the two formats. But some things may not translate well. For example, the G-code G00 (Rapid) does not exist in Conversational language.
G-code itself has variations among CNC machine platforms. The variant the TNC 151 uses claims to be close to the ISO RS-274-D standard. This differs from other manufacturers, so G-code generated for Fanuc might not be compatible. The TNC 151 has some particular requirements about G-code structure.
Simple jobs can keyed into the TNC 151 directly, in either Conversational or ISO (G-code) mode. These support subroutines and loops, so repetitive operations can be programmed once and executed at different locations.
For somewhat more complex jobs, the TNC 151 can export and export programs, in either Conversational or ISO (G-code) format, via a serial port to or from a computer. One can create and edit the job offline.
It is expected most users will want to use a CAD package to design a part, then build the tool paths for it in a CAM package, and export G-code. This could then be uploaded into program memory on the TNC 151 and executed.
Because program memory in the TNC 151 is limited by length, complex jobs will probably need to be sent to the machine using a "drip feed" where the computer sequentially feeds G-code instructions to the TNC 151 which executes them directly without storing them in memory.
Emulator
A TNC 151 emulator that runs under Windows is available for download at http://www.cnc-developments.fsnet.co.uk/ Note that this definitely supports Conversational mode, but it is unclear whether it supports G-code programming. It appears to be shareware, with some features limited.
Web Resources
- http://faculty.etsu.edu/hemphill/entc3710/heid-op/heid.htm - University course documentation using a similar setup. Note that it uses G-code, not Conversational mode.
- http://faculty.etsu.edu/hemphill/entc3710/nc-prog/index.htm - Discussion of CNC. The document appears unfinished.