Hoffman Mechatronics
Bridgeport Mill J1 Rebuild
to form the quill skirt around the quill, and then slide it into place and secure it with one of the
screws.
NOTE: On my mill, the quill skirt faced down with the tabs at the top, and the opening was
towards the pinion gear for the quill. If you put the quill skirt in upside down, you will only
have about 4” of movement on the quill. Do NOT force the quill down as you will most
likely break the tabs off of the quill skirt.
Once in place I move the quill down a little and started re-installing all of the quill feeds, stops,
and clutches. It was only after the quill was secured inside of the J-Head that I secured the
spindle shaft and tightened the spanner nut securing the spindle bearings. Once again, it is easier
to tighten this spanner nut while the quill assembly is in the machine.
4.5 On Machine Spindle Extraction
After disassembling my entire mill, it dawned on me that the spindle assembly could be removed
from the machine without removing the J-Head, in fact, without even removing the Quill. This
procedure requires you to build a custom press tool to press the spindle assembly out, and by
rotating the J-Head upside down, the same press may be used to reinstall the spindle.
As with the Quill and Spindle Removal identified in section 4.3, you will need to remove the
entire drive section from the top of the J-Head. Your goal is to free up the spindle so that nothing
is attached to it, but leave the spanner nut tight as you will be pushing out the whole spindle
assembly with bearings installed. Place a board or something on the table to protect the table in
the event that the spindle falls out. You should then remove the grub screw securing the Quill
Nosepiece, and remove the Quill Nosepiece. You will then want to bring the table up to within
6” of the quill. Use some 6” blocks to support the quill and bring the quill in contact with the
support blocks and lock the quill in place using the quill lock. Make sure that you have allowed
enough room for the spindle bearings to clear the Quill support blocks. You will then need to
install the press tool and secure it to the table using T-Nuts. Place a block on the table underneath
the spindle assembly to catch the spindle assembly should it fall out. As you crank down on the
bolt at the top of the press tool, the spindle should start to push out of the quill. Once the spindle
is free, you will need to lower the table to remove the spindle from the quill.
If after tightening the upper press bolt, the spindle does not appear to be moving, then you might
be best removing the entire assembly as detailed in section 4.3 above, and all you have lost is the
time to set up the blocks and press.
4.6 Feed Driving Gear Assembly RIR
The Feed Driving Gear Assembly provides you with 3 speeds and an on/off selector that can be
used for driving the quill feed. The upper sliding gear assembly is shifted right and left using the
Feed Gear Shift Fork, and the on/off with the Quill Feed Engagement Lever.
BPJ1RBLD_002
28
January 31, 201111