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Horizontal Expansion should use a ratio value instead of a fixed length


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Posted · Horizontal Expansion should use a ratio value instead of a fixed length

Horizontal Expansion, Initial Horizontal Expansion and Hole Horizontal Expansion should use a ratio value instead of a fixed length.


The Horizontal Expansion changes depending on the dimensions.
This means the bigger the measurement, the larger the Horizontal Expansion needs to be and vice versa.

My request is to change the fixed length offset to a ratio, depending on the dimensions of lengths and holes.

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    Posted (edited) · Horizontal Expansion should use a ratio value instead of a fixed length

    I printed up a hole chart with holes from 2 to 30mm.  I chamfered all holes top and bottom so my measurements would be of the walls.  I found that from 2 to 10mm the holes were .4mm undersize with very little deviation.  From 11 to 30mm the holes were consistently .2mm undersize with very little deviation.

    I was surprised by the results.  I had anticipated that there would be a fairly linear error (call it a ratio) with the largest error being on the smallest hole.

    As a result I was unable to develop a consistent "Snot Factor" for use with horizontal hole expansion.  If I have a part with large holes I set it to .1 and for holes 10mm and under I set it to .2.  This has worked out well enough for me since nothing I do is mission critical.  If a hole requires precise sizing I ream it with a drill bit.

    Holes that pass through a model anything other than vertically are what they are.  Again, a drill bit fixes any size (or out-of-round) problem if necessary.


    Regarding flat surfaces - is it a ratio?  If a machine can be calibrated by adjusting the steps/mm, and it's calibrated correctly, it might not be a ratio but a fixed number.  Gotta think on that a bit.


    I thought the Snot Factor would be my claim to fame but alas, it's not to be.

    Edited by GregValiant
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