Measurements and analysis
Platter bearing
After
wiping the bearing shaft relatively clean with a soft rag, the shaft appears to
have survived the past half century with minimal evidence of wear. In the photo
we can see very minor wear patterns indicating the location of the nylon
bushings relative to the shaft. But no evidence suggesting serious wear.
Measuring the shaft diameter to check for size top to bottom and around with a
Starrett No. 436 Zero to 1inch micrometer. This micrometer measures
to .0001 inch graduations.
result of measurements: diameter = .5505 inches all over. Circularity checks to less than .0001 inches of deviation. Using this instrument, there is no measurable evidence of wear.
Taking a look at the bearing shaft after wiping down with acetone.
Taking a look after polishing the shaft with clean cheese cloth. (just lightly
buffing with a clean dry cheese cloth)
After more polish......and then it is ready for another 50 years.
Taking a look at the bearing housing after the old nylon bushings have been
removed and new Oilite sintered bronze bushings pressed in. The photo also
shows some evidence of edge damage and burrs at the inside surface of the
housing flange near the large diameter. These will be dressed down flat with a
small fine cut file.
Looking through the new bushings from the top.
The prepared bearing housing, a new Delrin/Teflon thrust pad (brown disk), a new
6mm silicon nitride Ceramic bearing ball (black sphere), a new gasket, the
original three fastners and thrust cap.
Idler shaft & step pulley shaft
Both the idler wheel shaft (left) and the step pulley shaft (right) measure
nominal, no taper, good circularity and with no 'measureable' evidence of
wear. A visual inspection suggests that both parts have been in use but
not abused.