Print errors on bottom of WSF objects

Discussion in 'Technologies and Hardware' started by GWMT, Mar 20, 2011.

  1. GWMT
    GWMT New Member
    I've had several items printed in White, Strong & Flexible material and all of them have the same error in printing on the bottom surface. The outer edges are rounded off (and missing material) and there's a visible raised edge offset inwards from all the outer edges of the part:
    Coil Gon Hood HO bottom of print Closeup.jpg
     
  2. GWMT
    GWMT New Member
    Here's a shot of the top end of the part; it printed perfectly with nice sharp edges:
    Coil Gon Hood HO top of print Closeup.jpg
    Does anyone know why this happens? Is there anything that can be done with the 3D printer to get the bottom faces to print the same as the top?
     
  3. stannum
    stannum Well-Known Member
    SLS method melts the dust and it behaves differently for DownSkin than UpSkin.
    Check tables here
     
    Last edited: Mar 20, 2011
  4. Magic
    Magic Well-Known Member
    Yes, same issue here.
    See on this die (depth of the numbers is 0.75 mm, more than the minimum detail and even that the wall thickness in Strong and Flexible).
    The top and bottom are printed very differently. The number 2 is not readable, and thus I consider this print as a fail. The 13 in the opposite face is instead over-indented (or super-sharp).
    D14_issue.jpg

    Concerning the printing orientation, does the operator only turn the models by 90°? For instance, on a cubic die, if I want to avoid a number being on an horizontal plan, can I position the cube with on vertex up? Or is it useless because the operator can position back the cube so that two faces are horizontal?
     
  5. Youknowwho4eva
    Youknowwho4eva Shapeways Employee Community Team
    The orientation should be decided by a computer to include the most amount of objects in one load. At least that's how the printer worked that I have seen. It could even make the inside of your model honey combed automatically to cut out material and weight.
     
  6. crsdfr
    crsdfr New Member
    I'd hazard a guess that Shapeways have been using an auto-place for builds. There's pro's and con's to this - Computers can usually fit more in, but they'll never be able to account for all the factors a human can.

    On your cubic die, I'd upload the part oriented how you want it. If the computer/human operator doesn't have to re-orient it (likely on such a small part relative to the size of build packets), I'd see no reason why it wouldn't be built as such.
     
  7. Magic
    Magic Well-Known Member
    Yes I agree. On small objects that are nearly spherical, reorienting is probably useless. In this case, we should have the guarantee that they will never be reoriented so that we can optimize by ourselves this orientation.
    But does Shapeways agree? ;)