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sanding print lines in 3D printed parts?


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Technically, yes no matter what.  It will be a lot easier with SLA printed parts than FDM printed parts.  The SLA resin behaves a lot like the standard resin we've all used for aftermarket stuff for decades.  The biggest challenge would just be not sanding away any detail.

 

The filament used by FDM printers (most commonly PLA) is a bit rubbery, and doesn't sand the best.  A lot of people who do non-model making stuff use a 2 part epoxy brushed on to "fill in" the print lines as opposed to sanding them.  But then you soften detail.

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  • 2 weeks later...

I did just that tonight. Earlier I bought the Air-Graphics 1/72 SUU-11 gun pods (catalog number AC-104). They turned out to be 3D printed; the design looks great but the printing is quite coarse, with thick printing layers showing. See photo below.

 

I sprayed on a fairly thick layer of Tamiya Surface Primer, and then sanded it with 800 sandpaper, followed by 3M sanding foam, then a round of rescribing with a needle and a JLC razor saw. That took care of most of the layering. Then I sprayed on another fairly thick layer of Tamiya Surface Primer, and I will do a little bit of sanding tomorrow. That should give me usuable parts.

 

The trend to sell original 3D prints instead of resin cast parts is one that I don't like much. Why didn't the manufacturer do the work I did tonight once, and then cast dozens of great-looking resin parts that could be used straight away by the customers?

 

a1e-33.jpg

 

Rob

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An object that is well designed and printed well on a SLA printer should not look like those parts.  Even entry level hobbyist SLA printers can print parts that compete with, or exceed, top of the line resin casting.  However, this does requires some expertise and experience.  Printers need to be calibrated properly to the resin, be in a good environment (warm and fairly stable), manage cross sectional area (and often hollow models), and printed with a good orientation.  When printed with all these things tuned, you will not see layer lines.  The biggest challenge are the printer supports, which are much like sprue gates.  However there are many more of them, making cleanup tedious. 

 

Lack of knowledge can harm some of these, and speed/economy can push other issues.  Try to print in thicker layer lines (to an extent), or orientations that printer faster, can turn out more parts in a shorter time.  But they may not look as good. 

 

You also have to have a well designed part to start.  I have no knowledge of the 1:1 design here, and photos don't always display the issue well.  However, it looks to me like the design may be the issue here.  The photo looks more like a cylinder with a low resolution, depicting it as 15-20 straight segments.  All .STL files basically built in polygons, but better design programs will make cylinders out of dozens or even hundreds so it looks perfectly circular to the eye. 

 

Now FDM is a whole different story.  It definitely has it's use, but smooth surface finish is not one of them.

Edited by ESzczesniak
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Here's a follow-up on the Air-Graphics 1/72 SUU-11 gun pods. The parts were twice coated with Tamiya Surface Primer and carefully sanded and rescribed, then finished in MRP paint. I didn't have much faith in cleaning up the 3D printed parts, but I'll admit that they look excellent now. But all this work could have been avoided if the manufacturer had done his job.

 

a1e-49.jpg

 

Rob

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