A recent craigslist ad was a round ram Bridgeport with two "M" heads. The ram had the tongue at both ends and two M heads. I zoomed in on both Bridgeport emblems and one said "Spindle Bearings Greased For Life" ! This throws into disarray much of what has been read about open bearings being required for these heads. If that is true, certain later models had sealed bearings. They would still have to be matched precision bearings. The serial # of this head was obscured by overstamp in the first digits. Before going into that, the entire spindle lube system would be re-thought. There were open bearings from top to bottom, oiled from the top.
Over time people have mentioned they were going to replace lower bearings with sealed and it didn't make sense for worn oil to collect atop a sealed precision bearing. It looks as though some of these later heads had sealed bearings. The plate/emblem reads MB 84423. It must be at least 5 digits , may be M 34423 .
Bridgeport M head new old info
-
- Posts: 2366
- Joined: Tue Jan 20, 2009 9:33 pm
- Location: Phoenix ,AZ
Re: Bridgeport M head new old info
SPRO: Possibly the sealed bearing head was for an application such as woodworking where dripping oil would be a problem?
www.chaski.com
Re: Bridgeport M head new old info
Never heard of that. Get a get a router, then. The motor looks the same type, standard rpm. Over time I had reason to research posts and on occasion someone said the head had sealed bearings and they were just going to replace them. I never had a shot at this Bridgeport emblem/plate. Also the normal oiler cup is not visible.
Re: Bridgeport M head new old info
I don't know about M heads but some J heads certainly came with sealed spindle bearings.
Don Young
Re: Bridgeport M head new old info
Definitely.
Something which may be interesting is that the older motors are pigs. They are very good pigs. Whether U.S. Motors and others they had the outboard bearings external on the bell ends. The motor end was faced and the shaft was only 2 1/4" long BUT it projected into the mill head cover 4 1/4" . The step pulley receives near the full shaft length, because the driver step pulley is cast Wide at large diameter. Drive torque ( by 3/4" dia shaft) is by 2" of shaft .
The motor bearings are near inside the step pulley. They are ball bearings.
I just think it's neat how it worked.
Something which may be interesting is that the older motors are pigs. They are very good pigs. Whether U.S. Motors and others they had the outboard bearings external on the bell ends. The motor end was faced and the shaft was only 2 1/4" long BUT it projected into the mill head cover 4 1/4" . The step pulley receives near the full shaft length, because the driver step pulley is cast Wide at large diameter. Drive torque ( by 3/4" dia shaft) is by 2" of shaft .
The motor bearings are near inside the step pulley. They are ball bearings.
I just think it's neat how it worked.
Re: Bridgeport M head new old info
I was only talking "M " and other heads which are directly driven by pulley ratio. "J" heads' motors have the step pulleys opposite, for they go thru a transition to the spindle. Their stack is opposite, so the motor shaft can be shorter.
Re: Bridgeport M head new old info
Something else. The castings of the "M" head during WWII times is interesting. I don't think there two alike. One of my jobs in the '60's was grinding weldments and knowing how far to go on the surface without removing too much of the surface weld. Penetration was not uniform so removing too much on one side weakened the structure. It was "forming" the areas by grinding. They had to be presentable to final finish and paint but were rejected if the integrity was ground away.
So I can see the form grinding of one head and see the fillets and how the grinder was turned so the wheel removed in the pockets. A firm set of arms and w hen it skipped, how the person went back at it. My grinders were dang heavy and this was 25 years before. It is something to be able to "read" what that person did.
I've seen posts about things and there filler material and 3 coats of paint. I have one coat of paint and in good light....
I'm reading art looking at me .
So I can see the form grinding of one head and see the fillets and how the grinder was turned so the wheel removed in the pockets. A firm set of arms and w hen it skipped, how the person went back at it. My grinders were dang heavy and this was 25 years before. It is something to be able to "read" what that person did.
I've seen posts about things and there filler material and 3 coats of paint. I have one coat of paint and in good light....
I'm reading art looking at me .