bearings replacement - BT3000

Collapse
This topic is closed.
X
X
 
  • Time
  • Show
Clear All
new posts
  • woodturner
    Veteran Member
    • Jun 2008
    • 2047
    • Western Pennsylvania
    • General, Sears 21829, BT3100

    #16
    Originally posted by I saw that!
    I'm not a fan of heating bearings or bores.
    You raise good points and valid concerns.

    The purpose of heating the bearing is to expand it slightly, so it will fit over the shaft more easily. Interference fits need either pressure or expansion/contraction of one part to fit together.

    Shrinking the "inside" part - the shaft to fit the inner race, or the bearing to fit the outer race - is usually a safer option. Freezing the part will shrink it enough to fit, and is the normal practice in industry, at least for small to medium size bearings. In addition, it's easy to do at home and gives you more "working time" - just put the part to be shrunk in the freezer for 15 minutes.
    --------------------------------------------------
    Electrical Engineer by day, Woodworker by night

    Comment

    • mmcmac
      Forum Newbie
      • Nov 2014
      • 53

      #17
      Originally posted by capncarl
      Soak the pulley down in AWSOME for 15 min and all that stuff will come out with a sharpened stick. No sense risking cutting the pulley grooves.
      capncarl
      To clarify, the picture above is the urethane belt rather than the Al pulley. The debris was easily extracted from the belt with a nylon brush. The pulley (not pictured) has dings in the circumference and 40* V grooves which in cases results in raised burrs. Cleanup of burrs in the Al pulley grooves and circumference in a lathe is analogous to running a die on a damaged bolt to clean up projections in the thread profile. Eg, material extending beyond the intended profile is removed. In the case of the Al pulley and urethane belt the concern is accelerated belt wear due to the raised burrs.

      Comment

      • mmcmac
        Forum Newbie
        • Nov 2014
        • 53

        #18
        Originally posted by woodturner
        just put the part to be shrunk in the freezer for 15 minutes.
        Cooling indeed will help widen the temperature differential. It may however raise the concern of condensation onto the part before it is seated depending on the ambient humidity. Achieving a -40*C temperature differential via cooling the arbor assembly alone relative to a 20*C ambient, would require a drop to -20*C(-4*F) which could require specialized equipment. That said, assembly during a cold calm winter day would minimize the required casting temperature elevation. Although realistically bringing the casting uniformly to 140*F(60*C) shouldn't really be cause for concern.

        Comment

        Working...