HB2 Bearing Replacement (X – Axis)
Here is how I trimmed the Axis screws for the added thickness of the thrust washers (bearings). They are really being used as washers to keep the screws from impinging on the bearing seals.
I thought I might have to protect the screws when in the lathe chuck but I discovered clamping firm but lightly did no damage. Also the screw nut never gets that far down to each end of the screw. I generally use aluminum cut from a soda can for protection when needed.
I was surprised to see the “juices” leaking from the far end bearing The grease didn’t show while assembled.
The thrust washers turn with the screw shaft. The close up picture shows the washers do not ride against the bearing seals. They actually contact the flange on the inner ball bearing race. So in my opinion they are working perfectly as intended. Note the high quality of the thrust washer finished edge.
All axis screws are barely end loaded. Just barely on the loaded side of touching with zero end play.
After doing all the investigation and testing and more reading, I remembered a drive screw specification I studied long ago that affects how fast a drive screw can or should go in RPM. It all has to do with the end bearings support, screw diameter, unsuported length and preventing vibration. The best set ups are double bearings at both ends for rigidity. The lessons I learned here on the HB2 are the bearings ARE the most important factor for a good running machine. However, I doubt I need double bearings on each end. HB2’s screws theoretically could run over 3K RPM as they are. I’m not going there!
I have settled in on safe 120 FPM (600RPM) rapids and acceleration at 6 in/S/S.
Life is good.