Anybody know Bridgeport power feeds?

The power feed on my Bridgeport mill has started making a bad noise
when moving in one direction. The mill and power feed I bought new in
1981 and the power feed is the stock factory installed Bridgeport
brand power feed. When moving in one direction the power feed sounds
like it always has but when moving in the other it sounds like badly
meshing miter gears. Which is probably what the noise is. Maybe a gear
has become loose on its shaft and in one direction sounds good because
it is being pushed against some sort of stop which keeps it properly
engaged. But when the gear is spinning in the opposite direction it
moves out of proper engagement. Anyhow, before I take the drive apart
it would be nice to know if there is anything else I should be looking
for. Anybody know?
Thanks,
Eric
Reply to
etpm
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How about checking whether the leadscrew has a bit of end play. If it moves, it carries its gear with it. Likely the bearings at the end of the table just before the power feed and the crank.
Good Luck, DoN.
Reply to
DoN. Nichols
Thanks DoN, I'll take a look at that first once the cover is removed. Eric
Reply to
etpm
Bridgports use a preloaded pair of bearings at the left end of the screw to handle the screw's thrust. The bearing on the right (presumably where the power feed is mounted) floats axially.
Many clones (including my Supermax) have a single bearing at each end with the preload carried by tension in the screw. The Bridgeport arrangement is more reliable.
The Servo brand power feeds rely on the screw to maintain the position of the miter gear. Not sure if this is true of Bridgeport's feeds. I have a ca. 1981 BP manual with an exploded parts diagram, and it looks as though the miter gear's axial position is independent of the screw, but it's not entirely clear.
Reply to
Ned Simmons
Thanks Everyone for your replies. I just finished the fix. The big miter gear had backed off a tiny amount. I guess that's OK after 37 years of use. Like other folks I had added a drain hole to the drive. I was truly surprised to find no drain hole for the drive gearbox. Having to let the oil drain out around the cover is stupid. Eric
Reply to
etpm

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