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Machined bushings instead of rollers for CNC linear guide?

Discussion in 'CNC Mills/Routers' started by autox3d, Oct 7, 2015.

  1. autox3d

    autox3d Journeyman
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    I have been perusing the RS catalog and saw they sell a light duty linear guide that uses a bushing.

    That got me to thinking. What if I machined a polyethylene bushing for the profile aluminum?

    I ran a circular hole in some 12mm polyethylene and the aluminum profile rode on the corners only. It was really slippery.

    I am working on another design that has a little more mating surface to the profile to try that tomorrow.

    Seems like a interesting possibility.
     
  2. Joe Santarsiero

    Joe Santarsiero OB addict
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    Like this?
    linear_motion.jpg
     
  3. autox3d

    autox3d Journeyman
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  4. autox3d

    autox3d Journeyman
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    Works really nice...
     
  5. David the swarfer

    David the swarfer OpenBuilds Team
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    how will you adjust for wear? it will wear, everything wears (-:
    that is the beauty of the rollers/eccentric design, you can adjust for wear.
     
  6. autox3d

    autox3d Journeyman
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    Once it is worn i will just put a new one on. HDPE bushings on cars withstand much more friction than what I intend to put on it. It slides as well as my roller bearings using silicone spray.
     
  7. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    The one Joe shows in his post is designed for wear, using set screws that can be gradually tightened. Unfortunately they don't make them for the 20 series. Might be a good starting point for creating something however. The AlfaMill is another good source of ideas and uses a nice system of easily tightened glides.
    Use the silicone spray sparingly as it collects dust and grit which can easily sand the surface off your extrusion with enough repetition.
     
  8. Jonny Norris

    Jonny Norris Veteran
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    Out of interest, what happens if you try to slide by just pulling one side? ie to replicate a ballnut/lead nut plate. Does it bind up at all?
     
  9. Joe Santarsiero

    Joe Santarsiero OB addict
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    They don't bind, but as Rick mentioned they wear. I've ran into a couple of builds on the zone that used this system. Iirc they were pushing them past their limits and swapped the whole system out. I think they're a temporary solution based on load....as is everything else I guess.
     
  10. Jonny Norris

    Jonny Norris Veteran
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    Interesting concept nether the less, possibly not a solution for long term continuous actuation but could well be effective for say an atc sliding tool holder for example or something that isn't under stress or continuous use.

    Wonder how much load they could carry.
     

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