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leveling doesn't stay level

Discussion in 'CNC Mills/Routers' started by Mel Ristau, Sep 29, 2015.

  1. Mel Ristau

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    Not sure where this problem is coming from... I have two 1/2" layers of MDF (1200x1200mm) that I have screwed together and leveled. I shellac the leveled area so that my spray adhesive has better grip than raw MDF. Within 24 hours, different locations within a 24x24" area can vary by a whole millimeter.
    I'm cutting .025 aluminum sheet. So, that much variation is a problem. Is MDF easily effected by humidity change? Suggestions sincerely appreciated.
     
  2. Joe Santarsiero

    Joe Santarsiero OB addict
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    It most certainly is affected by humidity and barometric pressure. To say this is the cause of warpage is tough.
    I think the best way to approach this problem is to surface a spoilboard prior to your work. This will ensure that your work is parallel to your machines x and y.

    Joe
     
  3. Hytech2k

    Hytech2k Master
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    MDF is terrible in humid areas, at least here in Florida..... I surface my spoilboards every few weeks due to expansion... When I do aluminum or plastics I have a spoilboard for my spoilboard, usually a piece of scrap MDF or ply slightly larger than the pieces i'm cutting, I surface it just prior to cutting. Much faster to surface a small piece than the entire spoilboard...
     
  4. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    The shellac may be the problem. Sealing just one side causes non-uniform moisture absorption which induces cupping.
     
  5. Joe Santarsiero

    Joe Santarsiero OB addict
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    Different cte,s too. maybe install more screws.
     
  6. Mel Ristau

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    Thanks guys! Will use your suggestions and update on my progress.
     

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