Preface

All parts shown in this manual are PLA. The same steps apply to other materials as well. The only thing changing is the sandpaper grain sizes. Use coarser sandpaper for harder materials and finer for softer materials.

FDM Parts

1. Remove Supports and Skirt

Breakaway Supports (if there are any). Or cut them with a hobby knife. Then remove the skirt (If you printed one). First with a hobby knife and then with a deburring tool if you have one. If you don't I suggest you get one. There is nothing better to clean up printed parts.

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2. Coarse Sanding

Dry sand the part down with P80 grain sanding paper. The goal is to get a uniform surface. But don't sand too deep. It is OK if there are some printing artefacts left. We will take care of them in the next step. Also, always sand with a sanding block and never with just your hands. Otherwise, it is almost impossible to sand a straight edge.

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3. Paint filling

With a paintbrush, put a thick layer of paint on all the printing artefacts who are still visible. I use acrylic paint for that. But you could also use some glue, for example. You can also use paint to build up parts of the print. For example, if you have lifted corners or other unwanted printing artefacts who need build up. Make sure the paint is fully cured before you proceed to the next step.

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4. Coarse Sanding 2

Dry sand the part down with P120 grain sandpaper. After that, you should have a uniform surface all over. If there are any artefacts left. Repeat step 3 and 4.

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5. Filler

Mask everything who is not supposed to get painted with masking tape. Then spray the whole part with filler. There are different fillers available. I use a conventional car filler spray can. This is necessary to remove the marks of the coarse sandpaper we used in the previous steps. Make sure the filler is fully cured before you proceed to the next step.

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6. Fine Sanding

Remove the masking tape. Then wet sand the whole part with P600 sandpaper. You should sand until there is only filler left in the small crevasses created by the coarse sanding. You should now have an absolutely smooth surface. If you don't repeat step 5 and 6.

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7. Paint

The part is now ready for painting. Mask unpainted surfaces with masking tape again. I use a conventional car paint spray can to paint the part. But you could also use Airbrush. I always lay down two coats of paint. If you have some irregular spots after the first coat, you can wet sand them with a very fine P1000 sandpaper. Do not do that after the second coat of paint. It will leave some marks you will see in the end. Make sure the paint is fully cured before you proceed to the next step.

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8. Laquer

Lastly, apply one or two coats of matte lacquer over the part. Those are only for protection. Again I use regular car lacquer spray cans. But you could also use Airbrush. If you want to see how the part looks after applying lacquer, make it wet. This will give you a pretty good preview.

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DLP Parts

The good thing about DLP parts is, that they almost don't need any post-processing. Nevertheless, here are some steps I do to my DLP parts. Especially parts who have text or other engravings in them.

Without engraving

I leave parts who have no engraving in them mostly unprocessed. I only use some P600 fine sandpaper to sand away any print lines who are visible. So I get a smooth surface.

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With engraving

1. Thin paint

Thin some paint with quite a bit of water. I use acrylic paint. Then fill all the engravings with that thin paint. The thinning of the paint makes sure that the paint will flow into every small part of the engraving. Make sure the paint is fully cured before you proceed to the next step.

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2. Thick paint

Fill the engraving again, with thicker paint (right out of the tube, or only slightly thinned). Make sure the engraving is now fully covered. It is a good idea to overfill the engraving slightly. Most paints are contracting when they dry, so you might have to repeat this step.

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3. Sanding

Use some fine P400 sandpaper so dry sand off the excess paint.

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4. Polishing

Use some very fine P1000 sandpaper to dry polish the part. This should leave you with a perfectly uniform surface.

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5. Lacquer

Apply one or two coats of lacquer. This is to protect the part. I use conventional matte car lacquer spray can paint.

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