Bearings

Discussion in 'Design and Modeling' started by Robotex, Sep 9, 2013.

  1. Robotex
    Robotex New Member
    Hello.

    Is it possible to print good bearings from nylon? How minimal size can it have?

    If I have speed 500-1000 rpm with load do I need ball bearings? Will be friction between plastic surfaces with oil small in this case?

    Best regards,
    Nick
     
    Last edited: Sep 9, 2013
  2. FreeRangeBrain
    FreeRangeBrain New Member
    Sintered nylon, being very porous, is not a good bearing material. Printed WSF (nylon) will not be accurate enough to produce a smooth, round bearing for those kinds of speeds, load or no load. You may try it if you like, but I wouldn't bet the farm on the results.
     
  3. Robotex
    Robotex New Member
    So, sleeve will be better in this case, am I right?
     
  4. FreeRangeBrain
    FreeRangeBrain New Member
    Yes. Just make sure you have a significant area in the journal. The surface is like sandpaper except that the sand is nylon and something on the order of 400 grit as a raw powder with roughness increased depending on "clumping" as sintered and resolution of the print voxels. Expect the bearing to seat in fairly quickly as the higher lumps wear off. You haven't mentioned your intended shaft diameter, so keep the surface speed in mind and try to limit the loading so as to minimise heat input - excessive heat will make your nice nylon bearing a viscous nylon coupling!
     
    Last edited: Sep 9, 2013
  5. Robotex
    Robotex New Member
    What material can I use to get good rotations?
     
  6. FreeRangeBrain
    FreeRangeBrain New Member
    You haven't given anywhere near enough information to render an engineering opinion, let alone my lack of intimate knowledge of the performance characteristics of the individual materials offered by Shapeways. Take a long, careful look at each material's specification page, including the tolerance and print resolution data. For something as precise as a bearing usually is, I can't recommend any of them for anything more than trivial use. If it's something as simple as a child's pinwheel, anything will do. If it's going to see appreciable loads or speeds, I'd simply use an off-the-shelf bearing. (Your local hobby shop may be of particular service in this area.)
     
  7. Robotex
    Robotex New Member
    Stainless Steel has the same problems, am I right?
     
  8. FreeRangeBrain
    FreeRangeBrain New Member
    At the very least, accuracy. Right.