Duro Benchmaster spindle bearings.

[Bob S.]

A friend I work with has one of these mills. He says the bearings feel hot when its run on the highest speed. How warm should they get?
Does any one know how the preload is set? or where to get a manual? Thanks,Bob

 

[Bob S.]

Hello Bob,
The Duro benchmaster came in a number of varied formats, to my knowledge all used timken roller bearings,

Temperature wise there are a few rules, high speed spindles need oil not grease lubrication other wise they will get very hot, internal temperatures should not exceed 80 degrees C which means surface you can feel should under no circumstances exceed 60 or so degrees which is pretty dang hot, now another issue is that given the design the high speed may have been increased with a motor change or pulley change or whatever, so don't assume that the speed is actually what is marked on the tag 60-70 years after manufacture.

I would guess that continual dripping from old spindle seals, has urged someone to lube with grease instead "cos it works in car wheel bearings" and this has lead to heating, keep an eye on it, but don't fret over it, change back to oil if possible, and never run it too hot.

If your friend decides to do a tear down, smeone may have specific data related to the duro, if not I can give as much generic bearing setup advice as you might require.

Oh and photos for a machine ID check please, just so we know what it is

Best regards
Rick

Thanks Rick, no wonder they got warm. He just go the machine cleaned up and ready for use but didn't take the spindle bearings apart. I hope there was some lubrication in them. Bob S