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Double belt slack

Discussion in 'CNC Mills/Routers' started by nate campbell, Feb 14, 2016.

  1. nate campbell

    nate campbell Journeyman
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    Anyone else with a double belt setup fighting with slack on the top belt?

    On my machine with gt3 belts I can see the top belt moving as the carriages change direction. It will pop up off the bottom belt but some times not really become unaligned the the teeth on the bottom belt. Other times I can follow it from under the wheels of the and it is interlocked but at some point it will there will be slack in it. Hoping it's not related to my bottom belts.
     
  2. David the swarfer

    David the swarfer OpenBuilds Team
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    the top and bottom belts must be at the same tension.
     
  3. nate campbell

    nate campbell Journeyman
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    for me that seems easier said than done...
     
  4. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Did you put anything beneath the lower belt like foam tape to tighten up the gap under the wheels?
     
  5. nate campbell

    nate campbell Journeyman
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    no, used fairly thin double sided tape. I was thinking about this today. Have people had success with this?
     
  6. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Yes, and no. My ox is still a work in progress but I figured out fairly quickly that unless the gap was filled, holding the teeth in the belts together beneath the wheels the upper belt would slip relative to the lower one which is what it sounds like yours is doing. The problem came however in trying to get the belts to stick to the foam tape. Something about the belts having low surface energy causes them not to want to stick to the acrylic 3m foam tape adhesive. I finally worked out a system of applying adhesive to the back of the belt, letting it dry and then sticking the tape to the dried adhesive. This created a much more stickable surface. But this is where I stalled out and haven't gotten back to it....

    The tape should be in the 0.040" to 0.045" thickness range for the gt3 belt.
     
  7. Jonny Norris

    Jonny Norris Veteran
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    I had the same problem with slack in a single belt. In the end I layed my hands on a buckle arrangement like adjusters on ruck sack straps, one could use one of these at each end of axis. One for top belt and one for the other belt.

    They are simply a 1.5mm 5mm wide strip of steel with two squares cut out that make up the buckle and a fixing hole.
     
    GrayUK likes this.

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