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What bearing style for best Price vs Tolerance?

Discussion in 'CNC Mills/Routers' started by digdug18, Oct 11, 2017.

  1. digdug18

    digdug18 New

    Oct 11, 2017
    Likes Received:
    I'm looking at building a wooden or possibly an aluminum cnc router. But some of the basics are rather confusing to me, one of which is the styles of linear rails/bearings.

    For example:

    Aluminum bars with standoff blocks on each end, and a bearing in the center.
    15pcs Optical Axis Guide Bearing Housings Aluminum Rail Shaft Support Screws Set CNC Parts

    Squarish bar with a linear rail.
    MGN12 500mm Linear Rail Guide with MGN12H Block CNC Tool

    Supported linear rail with a bearing.
    SBR12 800mm Supported Linear Rails Shaft Rod With 2pcs SBR12UU Block Bearing

    Which is the best? is there an ideal design, provided tolerances are same across all 3?
  2. Jonathon Duerig

    Jonathon Duerig Journeyman

    Nov 25, 2015
    Likes Received:
    Of the three, this is likely to be your best bet:

    MGN12 500mm Linear Rail Guide with MGN12H Block CNC Tool

    You can screw it down to something more solid, like a V-slot beam. The unsupported shafts are likely to bend in the middle. The odd shaft-on-a-pedastal design doesn't look that much more solid than just the shafts alone to me.

    OTOH, in all three cases, you are ordering something shipped across the ocean from the cheapest supplier with no track record. So don't be surprised if there is an issue. Maybe order an extra in case one of them doesn't work or is damaged in transit.

    ltfy likes this.

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