H-M Supporter - Gold Member ($25)
- Apr 12, 2013
I swear I read or was told (under directions from a career machinist to allow some warmup time before cutting anything high precision) that lathe bearings should warm a bit after long runs. I followed the instructions to preload the bearings on my QC54 when I changed them out a few years ago, and rechecked/re-tightened them by backing off a turn and re-tightening per spec several times as they 'ran in'...and did have a bit of loosening for the first couple of hours. Recently I spent a few days running it long hours on a project and idly checked the temperature...stone cold. Same temperature as the surrounding metal. No measurable rise using an IR temperature gun. I don't have any felt play in the spindle but still wonder if I should tighten the preload collar another tooth or two. I was lead to understand that properly tightened lathe spindle bearings should have 5-10 degrees of warming after 30 min+ of runtime. True or false???