Lathe bearing design

Journal bearing
https://web.archive.org/web/20070306023517/www.stiweb.com/appnotes/jb.htm Journal bearing must not be round.

The damping properties of the lubricant also provides an excellent medium for limiting vibration transmission. Thus, a vibration measurement taken at the bearing outer shell will not represent the actual vibration experienced by the rotor within its bearing clearances.

http://bbs.homeshopmachinist.net/threads/26578-Bronze-sleeves-in-a-S-B-9-quot-headstock Again though, I did not come up with this method of repair. I got the idea from the article titled  " Line boring a South Bend lathe headstock "in the jan/feb 2007 issue of Home shop machinist magazine. The Author was Jack Butz. (google Jack Butz home shop machinist for xml file listing all articles).

http://bbs.homeshopmachinist.net/threads/26578-Bronze-sleeves-in-a-S-B-9-quot-headstock/page2 The top oiler is a tried and true setup. The artisan lathe I have uses this method with the same axial oil goove. It's much older than the southbend I have. The spindle is excellent and the cast iron bearing surfaces are so good and unworn that all the hand scraping is still there. I give it a few drops of oil and run it. If there was a high pressure area there it would force the oil out the top and this simply does not happen unless I over load with to much oil. In operation it drains and exits out the sides near the bottom.

Very smooth running. The oil does not fly all over but rather dribbles out slowly. Also I can add oil to the top oiler while it is cutting and under load and note a substantial rpm drop indicating the oil was indeed pulled into the journal and flooded it. Not until enough oil is squeezed out will the rpm go back to normal.

Even if the bearing was loaded at the exact top, the groove is recessed so oil would be forced to fill this groove and then flow and lube the journal. But I do not think the pressure area is exactly at the top under cutting load or lathe builders would have seen this early on and never used top oilers. It is no where near the top if you look at the link I provided on a standard spinning shaft.

SB also did use a top oiler early on. I visited several sites on the axial groove for plain bearings. Also load is very transient on the spindle. The machine is constantly turned on and off, cutting forces start and stop and belt tension is on and off. Every time this happens new oil will enter by gravity feed. This gives plenty of time to rebuild the oil film and plenty of oil will reach the journal each time spindle load is removed in your worst case scenario.

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Machine design, Lathe

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