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overhang difficulties


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Posted · overhang difficulties

Hi,

For a while I am trying to print a kind of bowl in PLA (photo album attached) .I tried different temperatures between 210 and 225°C with different speeds . The infill was always set to 20% . Also not changed the shell thickness . When it is printing the lower part, it makes contact with the material, because of a deformation by the temperature I guess . I used brim an then raft to prevent this . Raft helped but not completely . Do I need another support structure ? Must I look at the other settings within Cura ?

Thanks,

Aum

Foto Op 11 11 1346 Om 10.23Foto Op 11 11 1346 Om 10.24

 

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    Posted · overhang difficulties

    Hi Aum,

    I think you should try lower a temperature. 210°C is already 'fairly hot' for most PLA so try 205 or even 200 with a lower print speed and high fan speed.

    You can choose a different speed for outlines and infill. Let's say 30 mm/sec for outlines and 60 mm/sec for infill (at 0.1 mm layer hight). So you keep the speed but increase surface quality.

    Hope this solves your issue! Groet, Bas

     

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    Posted · overhang difficulties

    Hello Bas,

    Thank you for your reply . I now feel more sure about what to do . I am preparing a new print on this moment with the settings you mentioned . These are a bit more extreme than what I tried before, so this could be positive .

    This is print is estimated to take 21 hours, but the lower part might be visible by tonight . I will let you know the result,

    Dankjewel !

    Aum.

     

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    Posted · overhang difficulties

    I have this problem all the time when I print something of this shape. I don't know what to do. It is caused by the plastic on the upper layers shrinking and pulling. It will lift the edges of your bowl and the printer will hit it. Usually the solution for me is to just make sure it sticks very well to the print bed. THAT I am an expert on.

    So if your problem is that the part came off the bed then I can help you. But if your problem is trying to reduce how much the nozzle hits the part - let me know if you figure it out. You might need a heated bed or even a heated chamber.

    If the part is simply ugly you could reduce flow to maybe 30% during this part of the bowl and then increase gradually to 100% as the walls get more vertical.

    Let us know if you figure it out.

    Other things that help is support structure - sometimes I put support structure into the CAD model - posts to help hold things down. This doesn't work though for a bowl shape. It helped when I printed out some propellers though - I only had to hold down the outer edge with a thin support.

    Recently it seemed like I had WORSE problems with lower temperatures but this was just a single print - I didn't test it very well. I'm thinking of doing tests to try to reduce this shrinking lifting.

    Also less infill helps a great deal but with a bowl I assume the part is hollow so you can't print with any less than that.

     

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    Posted · overhang difficulties

    Aum, this is just a guess, but you could try and print it upside down. The bowl doesn't seem to have very steep angles so your only problem would be the bottom (now at the top). If you then print with support material enabled you'd have the ugly area (where the support material touches) inside the bowl at the bottom (when you turn back). This area is usually covered by the bowl's contents and not visible but you could also sand it to make it prettier.

    Instead of using Cura's support material options, you could also try Meshmixer. Check out this video:

     

     

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    Posted · overhang difficulties

    Yes - rim-of-bowl down is probably a great idea.

     

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