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Dunc
12-25-2009, 03:24 PM
Fenner's Mini-Lathe book (page 16) mentions adding an "oilway and internal oil grooves" to the bearing bronze (I assume) leadscrew bearings.
While the oil-holes are obviously situated on the top of the bearing (as installed) to allow gravity to do its work I hope someone could provide a few pointers.

1. Is a special drill or technique employed to make certain the drill exits cleanly (from the bearing material into the leadscrew opening)? Assuming some swarf remains at the edge of the hole, how would it be removed? Reamer, or?

2. Should some sort of oil reservoir (little brass cups) be added at the outside of the bearing?

3. The book continues with: "... internal oil grooves." What direction(s) should these grooves take - ie., diagonally across the bearing, circularly around the inner diameter, or ...? Tooling/setup to create these grooves? Should the groove(s) extend to the outer edge of the bearing to allow oil to flow out or are the grooves blind-ending?

Any general thoughts on the "hows" of bearing oiling appreciated.

Machinist-Guide
12-25-2009, 04:06 PM
I would cut a grove at each end of the bushing and connect them with 2 groves spaced 180 deg. You can do the long grove on the lathe. Us a HSS tool bit ground as a grooving tool or parting tool. Turn it on its side and hand crank the carriage to use the tool like a broach.
It's kind of hard to explane this with out pics

TGTool
12-25-2009, 04:43 PM
My recollection of oil grooves I've seen might be something like a blind ended groove made with an 1/8" ball cutter intersecting the oil hole. It spreads the oil to make sure one end or the other doesn't get dry if oil migrates one direction for whatever reason. Die bushings also frequently have a figure 8 groove on the inside, but that's pretty tricky without computer control.

Oil cups are nice reservoirs and the spring loaded lids keep out the trash. You can get them from McMaster Carr and probably others. And if you want to meter the oil a piece of shoestring will parcel lubrication.