Thin walled object surface finish.

Hello,

I have printed a thin walled hemisphere for a wind speed indicator, please see the attached photo.
I was wondering if anyone had and thoughts on how I could improve the surface finish.
If you look closely the outer perimeter has gaps scattered across it. Is it possible to close these up or is this just a limitation of printing thin walled objects? I don't seem to have this problem with solid objects when using the same slicing settings.
I used skeinforge to slice the stl file with a layer height if 0.3mm and layer width of 0.5mm. The actual wall thickness of the part is 1mm.

I'm interested to know your thoughts

Thanks

Ross

wow looks nice! what is the printing thickness? 0.2mm? PLA i presume?

for the insides, did you have to use fillers?

Edited 1 time(s). Last edit at 03/14/2013 10:58AM by redreprap.

Finish does not look too bad in the picture.
Kisslicer improved my outer surfaces considerably. I am sure SF could match it but not sure what settings to adjust.

Kisslicer does not use random start points so you end up with a "seam" instead of random imperfections.

I printed it in ABS. I did have to use support material for the inside to prevent the top from sinking.

Perhaps I am being too picky about the finish

Check out "3d printig vapour smoothing" with Google.

... be careful with acetone vapour and thin walled parts - when the acetone softens the core, the part will deform ...

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Viktor
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Thanks, time to do a bit of experimenting I think.

I'd think a bit of sanding would be all you'd need to finish it well enough for an anemometer cup, although I don't think you're going to produce a true mirror finish without a bit of work and light overcoats of paint or similar in between sandings. At 1mm wall thickness, I wouldn't risk it's shape by introducing acetone into the equation.

fwiw, Scotch pads are a great source for a conformable sanding medium and they come in a variety of grit values.

Have a look at the "Clip" settings in Skeinforge. If Clip is activated, the default value should be 0.2 IIRC. What it does is stopping extrusion before a perimeter is completely finished (so that the nozzle would be exactly above the start point of the layer).
Twiddle the clip distance a bit; the smaller the value, the closer perimeter start and end points get.

Hope that helps.
Also, if you have not done it yet, it is extremely helpful to read the manual for every single option in Skeinforge (this may be painfully boring). Took me some days (partly due to lack of concentration and motivation), but after that, I roughly know what I can find where and what the sometimes cryptically named options do.

What is your nozzle diameter? I find the best results when the extrusion width is greater than the nozzle diameter.

> I used skeinforge to slice the stl file with a
> layer height if 0.3mm and layer width of 0.5mm.
> The actual wall thickness of the part is 1mm.

0.3mm is still a pretty rough setting. I would retry with 0.25 or 0.2mm layer height.