Hoffman Mechatronics
Bridgeport Mill J1 Rebuild
6.1.2 Lead Screw Bearings & Brackets Inspection
The lead screw bearing brackets house the bearings that support the lead screws, and because of
the force applied by the lead screws, they need to be inspected for cracks and wear. On my mill,
one of the brackets was broken where the lead screw bearings had been forced out through the
back of the bracket by the table power drive. These brackets are made of cast iron, and cannot be
easily repaired. I was fortunate enough to find a bracket from a gentleman who had performed a
CNC Conversion on his Bridgeport and made up new brackets. Figure 35 below illustrates the
broken bracket, and the replacement bracket is illustrated in Figure 36.
Figure 35 - Broken Bracket
6.1.3 Lead Screw Bearings & Brackets Reassembly
I began my reassembly of the brackets by pressing the bearings back into the brackets. This is
not really a press fit, but a slide in fit. There was no need for a true press fit on these bearings
since the bearing retainer will press the outer bearing races against the casting of the Bearing
Bracket. Figure 36 below shows the bearings installed in the bracket and waiting to be installed
on the lead screw and table.
BPJ1RBLD_002
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January 31, 201111
