Spindle break in procedure on the hf 40939 bench knee milling machine.
MINDLESS BORING: Breaking in the spindle bearings on a harbor freight 40939 bench knee mill is of the first things to be done on a new machine before cutting any metal. The spindle bearings on the 40939 mill are sealed taper roller bearings that do not require maintenance lubrication as they are greased and sealed at the factory. As per usual the harbor freight owners manual is devoid of many diagrams and photos that are included in the grizzly g3102 mill owners manual and i suggest you cross reference this material for information concerning the 6x26 bench knee mill. The spindle bearing break in procedure gleaned from reading both of these manual leads me to run the 40939 mill in every speed for 10 minutes in both forward and reverse directions.
In this video, I show you my new hf 40939 mill on its first run at the lowest speed setting done by changing the belts to the correct pulleys. I would also advise a warm up period of the spindle bearings prior to any milling operations if shop temperatures are on the cool side, as i have not been able to verify the viscosity or type of grease used in the bearings. I have used this break in and warm up protocol on all of my Asian made machine tools including my bigdog mini lathe and have yet to have any problems with the spindle bearings in these machines.
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