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Pushing the edge of print volume

Discussion in 'General Questions' started by OutsourcedGuru, Jun 12, 2017.

  1. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Get your first layer a little closer to the bed and it will stick better.
    Now that doesn't mean that taller, thinner prints wouldn't benefit from a raft, but anything with a decent base should be fine.
     
  2. OutsourcedGuru

    OutsourcedGuru Active Member

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    Yeah, you're coming up to speed quickly. As suggested in some thread here (maybe this one), the trick isn't to hold the raft down but to prevent it from curling up. I noticed that holding the raft down via clips resulted in z-related problems in the part.

    Blog posts on this: one, two, three

    On adhesion, I'm finding that the test BuildTak sheet as provided by Robo 3D is working better than the tape (as long as you seriously adjust the z-offset since it has a tendency to super-adhere or so I've found). I actually had to pop the bed in the freezer one time to get the part to release.

    The clips as seen in the blog work reasonably well if you baby-sit them. I wouldn't recommend them, however. Note that I heavily tweaked the printer profile to print within about 5mm from all outside edges there.

    Oh, and be sensitive to the space below the bed when the printer homes. A clip fell off once and the bed wanted to grind into it there.
     
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  3. Frank van Gilluwe

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    Thanks for the blogs! Hoping my front magnetic cover/door project will help reduce curling too. Printed all the parts (7). I was almost finished when I drilled one of the last holes in the clear acrylic cover and it cracked :( I was drilling with a power hand tool - not ideal. Ordered a small drill press I've always wanted, which will solve that problem and should be back in operation later today. Gives me a chance to tweak the design slightly more too.

    I also noticed it's really hard to get exact long dimensional accuracy. I have one part that is 5.5" long that I rotate 45 degrees so it prints. Had to design it 1.5mm longer to get the right printed size. Only took 5 prints to figure this out (maybe I'm a bit slow!). Perhaps that's expected and/or different PLA would work better. Using Robo Black PLA. Not sure I've seen a spec on how tight the results should be or if there is some compensation for the printer or material shrinkage. It is only 1% off so I'm not complaining. I still find it amazing how well it does work.
     
  4. OutsourcedGuru

    OutsourcedGuru Active Member

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    Don't know if you've read this yet, but I've made a similar comment. Screw holes were laughably-small when z-oriented, like 3:4 ratio or something like that. (I'm slicing with Cura, for what it's worth.)

    As for heat inside the box, you can also see here where my initial attempt was using clingwrap (shrinkwrap) and I honestly didn't notice any difference.

    I'll eventually work up replacement STL objects for the aluminum bolts and hardware I intend to embed in parts (sized for the z-orientation).
     
  5. Frank van Gilluwe

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    Thanks! I hadn't caught those posts. I've see the same thing with holes. Usually takes 2-3 resizing tries to get it where it works for me, and usually redrilling also works well. I haven't done any holes on the z-face, but have done some z-text which has come out fairly good.
     
  6. OutsourcedGuru

    OutsourcedGuru Active Member

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    To the best of my knowledge, any Y- or X-facing holes size up okay. It's just when you're trying to make two box parts that screw together, say, and you want to use a stock bolt with industry threading.

    So I printed a bolt gauge (like you might see at a hardware store) and tried to fit each bolt. An M4 fit better into the M5 hole, the M3 fit better into the M4 hole, etc.
     

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