Smoothing Out The Top Layer

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Smoothing Out The Top Layer

Postby Radioman1017 » 2015-Mar-Thu-19-Mar

Hello all,

Do you all have any recommendations on smoothing out the top layer? Let's say I'm printing a box. The bottom layer (on the bed) is usually nice and flat. The top layer, especially if there is fill material (I usually use honeycomb) is oftentimes not very flat and the hex grid shows through. I'd like that top layer to be a little more solid and smooth. I'm running the fan and my PLA temp is 185 but I'm still not happy with that layer. Any tips?

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Smoothing Out The Top Layer

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Re: Smoothing Out The Top Layer

Postby nikbrewer » 2015-Mar-Thu-19-Mar

increase the number of top layers.
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Re: Smoothing Out The Top Layer

Postby RetireeJay » 2015-Mar-Thu-20-Mar

I usually print 4 perimeter layers all around (bottom, sides, and top).

I think that for the very smoothest top surface, you need to make sure that your extruder is calibrated correctly (steps per millimeter of incoming filament) and that you tell your slicer the exact diameter of your actual filament (not just the "specified" diameter). Measure this carefully, being aware that the cross-section may be oval instead of circular; take the average of several readings. Make sure that the flat on the very bottom of your nozzle is clean and smooth. Tweak the Extrusion Multiplier if necessary.
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Re: Smoothing Out The Top Layer

Postby frankv » 2015-Mar-Thu-22-Mar

I've wondered about this too... how to get a nice smooth surface on PLA.

So here's the results of a couple of hours Googling and reading...

I've tried using a 2kW hairdryer, and I think that made a difference, although only marginally.

I wonder about a clothing iron for smoothing larger flatter surfaces? Incidentally, in case anyone tries this, you can use a sheet of baking paper between the iron and the plastic so nothing sticks to the iron.

Acetone fumes work for ABS, and THF is more or less equivalent for PLA (http://www.protoparadigm.com/news-updates/vapor-smoothing-and-polishing-pla-with-tetrahydrofuran-thf/). There's a significant amount of THF in PVC solvent used for gluing together drainpipes. I did experiment with this, but didn't see any difference after a week. There are other chemicals that have been experimented with... Ethyl acetate seems to be the most promising.

This page http://www.instructables.com/id/3D-Print-Finishing-Technique-for-Improved-Surface-/ says to sandblast your part.

Other people suggest filling with automotive body filler and then sanding.

XTC-3D paint http://www.3ders.org/articles/20141117-xtc-3d-brush-on-coating-gives-3d-printed-parts-a-shiny-smooth-finish.html is mentioned in a couple of places.
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Re: Smoothing Out The Top Layer

Postby ThereWillBprints2 » 2015-Apr-Mon-20-Apr

Smooth layers are all about nozzle calibration. Most people believe you can switch tips and one or two settings, it is not true. The oozing effect of your temp and the quality of the pla play a vital part.

RetireeJay is correct also, steps must be measured and calibrated. Without it, well good luck. I know it sounds crazy, but if you go to youtube and watch Brook run a printer, it sounds like a musical. Your machine should sound the same. My nicest prints have sounded better than a new video game powering on Xmas morning.

Look for a slicer that has the least amount of paths and you will find your smooth layers on any side.
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Re: Smoothing Out The Top Layer

Postby Alastair010 » 2015-May-Fri-06-May

Hey you have to smoothest top surface, and to make sure that your extruder is correctly calibrated and then you tell your slicer the exact diameter of your actual filament. Measure it carefully, being aware that the cross-section may be oval instead of circular, and take the average of several readings. Make sure that the flat on the very bottom of your nozzle is clean and smooth.
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Re: Smoothing Out The Top Layer

Postby lairdb » 2017-Feb-Thu-15-Feb

I always wonder in these discussion what people mean by "smooth" -- I might think my output is smooth because I don't have grid marks and pillows, and Cletus might think his is not smooth because it's not Rayleigth smooth at 580nm at 45deg incidence.

Here's a picture from 3dverkstan's visual troubleshooting guide (http://support.3dverkstan.se/article/23 ... ting-guide):

Image

Clearly the bottom is not smooth. Would you all describe the top as smooth? Is that a reasonable limit for achievably smooth?

Does anyone have a picture of a flat top surface that is most perfectly achievably smooth?

FWIW, I would describe the top as "pretty smooth", but I'd prefer it smoother. It helps that there are no holes or features in teh top of this, though, so there are no intermediary moves. Also from the same source, under the "Scratches" heading:

Image

These are the ones that plague me on otherwise... sufficiently smooth... surfaces, and that I'd like to get rid of.
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