Vertical radius inconsistency

[johnsquared1978]

Not sure I'm calling this the right thing, but I'm having a hard time getting vertical radii to print accurately.

I'm printing the object shown in the rendering below (http://www.thingiverse.com/thing:1802260) but the edges are not printing evenly. The radius on the top half - where the layers are successively smaller - is printing beautifully. However, the bottom half - where it is building outward - is inconsistent.

Using PLA on an M2e via Simplify3d

The default presets for "high" quality seem to produce the best results, though not perfect.

I've tried slightly lower bed (65) & extruder (210) temps, different fan speeds (50% & 100%), Infill (30%, 40%, and 50%). All produce the same problem in varying degrees.

Would love some tips if anyone has any!

[3dPrintingMD]

On the Layer Tab in S3D, are you printing outside - inside, or inside - outside ?

Outline Direction; Inside-Out: It will print your perimeter shells from the inner shell to the outer most shell. This is very beneficial when printing overhangs, as the print is branching out in the X-Y direction for each layer.

Outline Direction; Outside-In; It will print your perimeter shells from the outer most shell to the inner most shell. This is better for surface quality finish usually. For instance, if printing a cube, this may be the better route.

You really want to do inside-out for this type of print due to overhang.

[Jules]

Had the same problem with some egg shapes I was trying to print...rounded deep undercuts on the bottom of a print don't do well for mechanical reasons.

1. Use two outlines and Inside-Outside print direction as 3dPrintingMD suggested.
2. Point a separate desk fan at it at the back to cool the bottom as much as you can - that deformed shaping on the part that was facing away from the fan is caused by PLA not cooling quickly enough.
3. Try the PLA+ filament. (eSun) I did the same print in PLA+ and it came out perfect. (Different formulation.) Made a big difference in the print.

[ksevcik]

Haven't tried this kind of print before, but I would think a larger extrusion width would handle overhangs better, since it moves the center of the extrusion path more over the previous layer. Thinner layers with the same extrusion width would probably help too.

[3dPrintingMD]

Hey John,

Any updates? I would be happy to look at your profile and compare it to mine.

[jimc]

inside perimeter first, lower layer heights and wider extrusion widths are key to doing overhangs. in s3d use the cross section tool in the x or y and slice the model. in the overhang look at the extrusions. as it steps over the extrusion needs to print on the one below it by 50% or so. if it does not catch the one below by half then the less it overlaps the more sloppy your overhang is going to be.