Doug W
Hot Rolled
- Joined
- Sep 22, 2003
- Location
- Pacific NW
I have some general questions about lathe spindle bearing design and lubrication. First let me state that I have little experience in machine tool repair. However, I have extensive experience with automotive transmissions and axles etc.
In the near future I will be replacing the spindle bearings in my Logan 14”. The spindle design I guess is somewhat typical for a lathe of the 1950s. The spindle bearings at the chuck end are two opposing angular contact bearings with a spacer separating the outside races. A nut on the spindle adjusts bearing preload by forcing the inner races together. The bearings are of the factory greased sealed type with a labyrinth type seal mounted at the chuck end of the spindle. At the other end of the spindle is supported by 2 smaller sealed angular contact bearings. The lathe has a single gear keyed to the spindle, which is engaged only when the lathe is in back gear. This gear’s teeth are always in contact with a shallow oil bath in the headstock. The oil is not used to lubricate the spindle bearings only the gears. Max rpm of the spindle is 2000 rpms.
From my automotive experience I find this design very unusual. I am considering replacing the bearings with open cage (easier and much cheaper to find in precision classes) and mounting a trough to divert oil from the gear that slings oil to the spindle bearings. Since I don’t have much knowledge of other lathes headstock/spindle designs I have several questions.
1. I have read that oil at relatively low rpms is superior to grease for lubrication and cooling. What lathes use oil in a similar design?
2. Is there any reason for a Labyrinth seal in this application? A typical rubber garter spring seal would retain the oil and keep out the crud better. I know eventually the spindle (or wear sleeve) would get grooved.
3. Is there any concern for metal from gear wear being pumped through the spindle bearings? As mentioned the gears are only engaged in back gear.
4. Any other potential problems I am overlooking?
Doug W
In the near future I will be replacing the spindle bearings in my Logan 14”. The spindle design I guess is somewhat typical for a lathe of the 1950s. The spindle bearings at the chuck end are two opposing angular contact bearings with a spacer separating the outside races. A nut on the spindle adjusts bearing preload by forcing the inner races together. The bearings are of the factory greased sealed type with a labyrinth type seal mounted at the chuck end of the spindle. At the other end of the spindle is supported by 2 smaller sealed angular contact bearings. The lathe has a single gear keyed to the spindle, which is engaged only when the lathe is in back gear. This gear’s teeth are always in contact with a shallow oil bath in the headstock. The oil is not used to lubricate the spindle bearings only the gears. Max rpm of the spindle is 2000 rpms.
From my automotive experience I find this design very unusual. I am considering replacing the bearings with open cage (easier and much cheaper to find in precision classes) and mounting a trough to divert oil from the gear that slings oil to the spindle bearings. Since I don’t have much knowledge of other lathes headstock/spindle designs I have several questions.
1. I have read that oil at relatively low rpms is superior to grease for lubrication and cooling. What lathes use oil in a similar design?
2. Is there any reason for a Labyrinth seal in this application? A typical rubber garter spring seal would retain the oil and keep out the crud better. I know eventually the spindle (or wear sleeve) would get grooved.
3. Is there any concern for metal from gear wear being pumped through the spindle bearings? As mentioned the gears are only engaged in back gear.
4. Any other potential problems I am overlooking?
Doug W