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mevander

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Posts posted by mevander

  1. Have you tried decreasing your layer thickness or increasing your top/bottom thickness? You're only giving it 3 layers of material to work with there.

    If you've got good internal supports/lots of infill that might be okay, but I generally find I need at least 5-6 layers (and preferably more) to get a good looking top surface when printing over a hollow portion of a part. What usually happens is that the first layer will have some gaps/issues/broken bridges, and then those gradually get corrected on subsequent layers.

     

    The effect is for sure much less visible with thinner layers. I've seen the same surface effect even with 1 mm top layer though. Since you actually can see through the top layers you still get a pretty open surface even with thicker layers it seems.

     

  2. I just did a test with 15 x 15 x 3 mm cubes spaced out over the print area. I wanted to check if there was a large variation in the results as I've seen some lateral variations in previous prints. This test was done with PLA/PHA at 230C, 0.2 mm layers, 50 mm/s and 0.6 mm top/bottom surface. The results did vary a bit but on almost all places the top layer is not covering the surface and the side walls.

    Judging from what I've read and seen it looks a lot like what seems to be coupled with the short belts not being tight enough. A couple of days ago, I did unscrew the motors and push them as far down as I could so I'm not sure if that is what really going on or if there is anything else that can be done.

    Considering that the extrusion cylinder test looks fine on this instrument, could it still be under extrusion somehow? It really does look like it's not feeding enough material although this print was done at 4 mm^3/s (which works fine in the extrusion test at 230C).

    gallery_36523_1334_364094.jpg

    gallery_36523_1334_91582.jpg

     

  3. I've had similar problems with my UM2. It's most pronounced with 0.2 mm layers but can be seen with 0.1 mm layers as well. I've been in contact with Robert at 3dverkstan and we've tested tightening the short bands, performing atomic cleaning, aligning the bed and checking the nozzle for blocking. I've tested for under extrusion with the standard test and at 250C we're getting great results all the way up to 10 mm^3/s. At 210 C it fails already at 3 mm^3/s and at 220C it fails at 8 mm^3/2.

     

    I've attached an image showing a test print made at 220 C, 0.2 mm layers at 40 mm/s. The shell thickness was 0.8 mm and the top and bottom layers 0.6 mm. I've tested this at 230 C with pretty much the same result as well. I'm a bit stuck and am not sure what to try next :(

     

    /Mikael

    gallery_36523_1334_752806.jpg

     

  4. Hi!

    We've recently installed an Ultimaker 2 at work and I'm currently working on getting it set up and learn how it works. I was testing the "cool head lift" feature and also the "pause at height" plugin the other day and noticed that the nozzle keeps feeding material through the nozzle during both the cooling pause and when waiting for user input during the height pause. This created a large blob of material that was moved back into the model with not so very pretty end results.

    Is this supposed to happen, is there a setting that might help me here or what might be going on? If I look at the layers in Cura, it looks as if it is supposed to perform a retraction during the cool head lift but it didn't seem to happen?

    I must also thank you all for providing so much useful information in the forum. I've learned a ton by just browsing subjects and a don't believe our setup would have run very smoothly without all the collective know-how available here!

    Cheers

    /Mikael

     

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