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Getting the hang of it

peterb8f15b29
(@peterb8f15b29)
Famed Member

Hi All,

I have had tremendous support from Luke and I thank him for that. So I have attached my latest creation (still has the supports yet to be removed). I have still a long way to go but the help I am getting from Io3DP has been outstanding. So well explained and in detail.

Thank you Luke and all the rest of you.

Peter

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Topic starter Posted : 11/09/2021 11:20 am
Jess liked
peterb8f15b29
(@peterb8f15b29)
Famed Member

Sorry, Omitted the photo. Attached.

Peter

20210911 145345

 

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Topic starter Posted : 11/09/2021 11:36 am
Luke
 Luke
(@lmf5000)
Expert Moderator

Hi Peter,

Thanks for the lovely feedback about the support we've given you :). Always a pleasure to get positive feedback from members!

Regarding the print in your pic, there are a couple of defects visible which when addressed will drastically improve the appearance of your print.

For starters, this section of wall looks a bit rough -

image

There's a possibility that this is caused by underextrusion. If so, your walls will all be a little porous (sponge-like) and weak. To address this, start by calibrating your e-steps as outlined in the guide in the main community. Calibrating the e-steps will improve every aspect of the printer because it ensures the extruder axis moves exactly as far as the slicer commands.

Immediately after calibrating the e-steps and saving to the printer's EEPROM (or putting the commands in your start script to make them apply to each print), do an extrusion test. The traditional way to do this is to print a hollow cube and measure the wall thickness of the top few layers, then compare your measurement against the intended thickness (for example, if using vase mode with an extrusion width of 0.45mm you should be measuring 0.45mm at the walls). Your new extrusion multiplier should be intended thickness divided by measured thickness. For example if say you measured 0.46mm and the extrusion width was 0.45mm your new extrusion multiplier should be 0.45/0.46 = 0.978 (or round to 0.98 ; or enter as 98% depending on slicer).

If you want to save the print, or you don't have an accurate micrometer or two-decimal vernier caliper, the way I personally tweak extrusion multiplier is to print a calibration cube and look at the top surface. If gaps are visible between the diagonal lines, the extrusion multiplier should be bumped up. If you see excessive plastic (grooves or matte areas) at the ends of the diagonal lines, where they meet the perimeters, the extrusion multiplier should be reduced. Here's a visual indication:

image

Source (for more detail) - https://help.prusa3d.com/en/article/extrusion-multiplier-calibration_2257

In general with well-tuned e-steps, PLA would end up with an extrusion multiplier of 0.96-0.97 (though some printers require bigger adjustments).

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The second issue is called pillowing, where the infill pattern is visible in the top layers -

image

The cause is that the top layer is too loose and sags into the infill pattern. This is caused by too sparse an infill density, or too few top layers. Based on the scale of your print I think your infill density is fine, so you should increase the number of top layers to ensure at least around 0.6mm of skin thickness (eg. 3 layers at 0.2mm layer height). Prusaslicer makes this very easy because it will automatically add top/bottom layers to make up the required thickness if you change the layer height to finer layers if you set a minimum skin thickness. As a minimum, for thicker layers (say 0.3mm layer height) I would still recommend 3 layers minimum to seal off the surface reliably. So this is what I recommend in terms of settings in the layers page -

image

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Last observation is a lot of stringing. This will be harder to fix, because there are  multiple causes.

  • It could be caused by old filament that has absorbed moisture - make sure you keep filament spools in sealed (ziplock/resealable) bags with pouches of silica gel desiccant inside
  • Your retraction settings may be insufficient - try increasing retraction distance (recommended around 5-7mm for Bowdens and 1-2mm for direct-drive) and speed (recommend 50-70mm/s). Test whether it improves it with a retraction test print like this one - https://www.thingiverse.com/thing:909901
  • Make sure your print head is travelling through walls when possible (not over open spaces) to avoid leaving strings in the open space. Here's the setting to check under Print Settings -> Layers and Perimeters -
image

Hope these help, let me know how it all goes, and thanks again! 🙂

 

Regards,
Luke

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Posted : 11/09/2021 4:00 pm
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