Hoffman Mechatronics
Bridgeport Mill J1 Rebuild
Modulation (PWM) to the motor to maintain the selected RPMs even under load. I have done
this before in my line of work at 12 and 24VDC. I am just hoping that I don’t kill myself with the
90-110VDC that this motor requires.
The advantage to a system like this is that I no longer require 3-phase, and I will have precise
control of spindle speed. Since this motor has a max rated speed of 3800 RPMs, it will also allow
me to drive the spindle at slightly higher speeds which may be required for some CNC
operations.
3.3 Drive Housing Section
The Drive Housing Section, shown in figure 6 below, houses the stepped pulley assembly,
spindle brake assembly, and all of the spindle drive components for the mill including the back
gear. Within this assembly, the power from the motor is transmitted to the spindle through a
stepped pulley and v-belt system, and a timing belt arrangement. Power to the spindle may also
be directed through the back gear which provides a gear reduction unit that will allow spindle
speeds as low as 80 rotations per minute (RPMs).
Figure 6 - Drive Housing Assembly
3.3.1 Drive Housing Removal
You should first follow the steps for removing the motor. Once the motor has been removed, you
can remove the Drive Housing Assembly by removing the 3 bolts sown in Figure 7 below that
secure it to the J-Head and slide the assembly up and over the spindle.
BPJ1RBLD_002
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January 31, 201111
