Wanted: Finishing techniques for different materials

Hi folks, I just started with 3D printing and since I managed to do a couple of cool prints I am looking for advice on how to finish/polish the models. I couldn’t find any thread which pertains to making prints of different materials look great so I thought it would be worthwhile to create a thread to collect different ideas and techniques for various materials. I bet that the treatments will vary wildly with the material used.

I know that some people use their 3D printer just for rapid prototyping so they might not really be interested in making the end product look good, but I hope that there are enough folks here who want to make gifts and decorative objects for their home to engage in this discussion.

Example: I just started printing with HIPS and while I believe that I am in a good range in terms of print quality (future me will probably laugh about that statement :smiley:), I am looking for advice on how I can treat the surface of my model to get a great finish. Should I buy a Dremel with a couple of bits or should I buy sand paper? What grit size do you recommend? What about steel wool? Any experience with coatings? Are there paints and coatings I should stay away from because they can damage my model?

I’m also hoping to learn more about finishing techniques, but I’ll share a couple things I discovered recently while working on some PLA prints.

[] Sanding first with 180 or 220 grit and then 500 and up worked well for me to get a decent finish. Its hard to get a piece back to being as shiny as it was when first printed.
] I tried a polishing wheel on my dremel with ok but not great results. Polishing compound didn’t seem to help. Low speeds kept the wheel from ripping apart the plastic. I was surprised at how fast the wheel wore down the plastic.

Use ABS and then do an acetone vapor finish. Makes a super shiny smooth finish. Beware you will be vaporizing a strong chemical. Make sure you know what you are doing before you do it.

There are lots of articles on how to do it, google is your friend.

Thanks for the tips dustMason & wantmys2000! I did some research and found several tutorials for using vapor finishing for which seems to be a well established way to finish ABS models. However, since I use HIPS (for now - cheaper and lack of an enclosure) I can’t use acetone but I also found an additive way to make my models smoother: resin.

The resin in question is the Smooth-On XTC24 XTC-3D and there are also several review videos on Youtube from 3D printing enthusiasts who gave it a try. The verdict is positive so far so I ordered a batch to check it out. I will probably still have to sand the prints so I’ll also get some sand paper and some paint to get matte and gloss finishes.

Edit: Changed brand from Filabot to Smooth-On who is the actual company offering the finishing resin.

While I am waiting on my resin, I discovered this link with a couple of different techniques to finish/repair models. THat seems to be quite a comprehensive list of options: http://makezine.com/projects/make-34/skill-builder-finishing-and-post-processing-your-3d-printed-objects/

Alright - did a couple of tests with the epoxy resin and the results were a bit mixed in my opinion. The first challenge was that I never worked with resin and since I am very gifted at ignoring instruction manuals, I poured a good batch of the epoxy resin into a cup to mix it up and paint from. Now in case you don’t know… epoxy has a limited work time and when that is up it starts its polymerization which is quite an exothermic reaction depending on how much volume of epoxy you have.

When you apply it to a model, it takes several hours to harden. If you have a bit more of it in a enclosed volume, like a cup, it’s going to cure very fast… in like 10 minutes and the whole things get’s VERY hot. So once I noticed that my paper cup (I was lucky to not choose plastic) was getting hot and my foam brush started to melt, I knew it was time to put that infernal concoction on the garage floor and not keep it near my fingers or face :smiley:

Now for the result: The surface got super smooth through the epoxy which is a big plus. Big drawback - the resin was completely transparent and glossy which made the model look cheap and one could still see the grooves and see it was a 3D printed part. In additional to that, the epoxy also got rid of some details of the model since I wasn’t sure how thick the layer should be.

So I did a second run and added some food color this time and the model turned out better. To get rid of the gloss, I used some Army Painter Anti Shine Spray which gave the model a matte finish. I’ve attached small picture of the model in its current state below.

Here is also a link to high-res pictures in case you are interested: http://imgur.com/a/e2RrS

I now ordered some ABS to do some acetone vapor tests to see if I can skip the whole epoxy part. I fear that smaller models would maybe loose too much of the details since the epoxy is too syrup like to get in all the little spots. And I don’t want to throw away my brushes every time I paint something with epoxy :smiley:

Sorry to be so late on this thread. But I wanted to note that acetone smoothing on HIPS works a treat! It gets shiny once you first put it in. BUT…as I noted in a later post, the grey HIPS produces these weird spots when it dries.

I would be very interested in hearing what acetone smoothing on other HIPS colors produces. Or if different manufacturers produce better looking grey prints!


Eric Kunzendorf
Jacksonville University