| Since I have already built 2 different 3 axis-milling machines that use a PC control, I bought this Bridgeport and plan to do a PC retrofit on it. This machine came from a trade school and appears to be in excellent condition. I plan to run the mill from a home built 3 phase rotary converter and PC controller. I hope to have the spindle buttons work either manual or CNC controlled along with the coolant pump. |
| I new before purchasing the mill my garage door was 84" high and the mill was 89" high. The first challenge is to get the mill inside the garage before bad weather arrives. This was done during a January warm spell. One of my friends from the Internet provided the idea of mounting a 3/4" pin from the table to the spindle of the mill. The mill head was then removed from the rigid ram and left resting on the mill table. The machine knee was then used to lower the head down to the required clearance then raise the head back up after the mill was inside the garage. A hydraulic jack and block of wood was used to stabilize the head. A tie down strap was also used to lash the head to the rigid ram for additional safety. Below and to the right, the machine is safely inside the garage. I rigged up some caster wheels under the mill to make it easier to move. |
Very little of the Bridgeport electrical could be salvaged for the PC control other than motor contactors, fuses and some relays. One electrical enclosure was eliminated all together. The 3 phase transformer was too large for the driver boards I planed to use. A new DC power supply was built using a toroidal transformer, rectifier and capacitor.
The spindle is controlled from the original switches or from the CNC control as well. Spindle RPM is controlled with the original switch gear. The axis limit switches shut off power to the stepper motors any time a limit switch is activated. One problem with this, position is usually lost as the steppers coast to a stop. But, after three years the limit switches still work the same way. It has not been a problem. |
The mess The new control
- One person on the Internet claimed a laptop lacked the power to run a full size CNC machine. But, a laptop can run a large machine. The DC power supply really drives the machine, the laptop or desktop computer controls the DC power supply. In a way, the computer actually thinks it is controlling a printer instead of a machine tool. I run Turbocnc software from a Compaq computer, Pentium 266, Windows 98. The G-code is usually written on a separate computer from Microsoft Note Pad or other G-code generating software like engraving software. Turbocnc runs in DOS. Windows software is available but requires windows XP or newer versions of windows to run.
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| Write the G-code manually or generate it from software. Load it to the computer connected to the machine and you are ready to run. |
| Some of my first parts made on the retrofit Bridgeport. |
