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How to Smooth a 3D Print – It´s Really Easy Once You Know How

The possibilities that 3D printing unlocks for all of us are amazing and as time goes on more and more technologies and more use cases for 3D printing are found and developed. But one problem remains and will probably remain for quite some time and that is smoothing the print because you will probably see at least some print lines or have some kind of residue from supports. In this article, I will tell you how to smooth any kind of 3D print as easily and effectively as possible.

As a whole, the best ways to smooth 3D printed parts is by either applying a spray-on filler and then sanding the print until it is smooth enough or by using solvents to smooth the surface by melting the top layer slightly or by using epoxy resin to smooth the surface. For beginners, sanding will be the best way to smooth 3D prints.

If you don´t know how any or some of these methods actually work then don´t worry as I will explain how to use each of these methods to smooth your 3D prints.

You can see the results I got by smoothing my 3D prints by sanding and priming them in this video.

How to Smooth any 3D Print by Sanding and Priming

First up is the one method that I use the most and I also recommend for every beginner. Sanding the 3D print but I have a slightly different approach that will speed the whole tedious work a little up and remove some of the tedium from sanding a whole model.

As a whole, to smooth a 3D printed part it is important to start with a rougher 120 grit sandpaper first to remove uneven parts from the surface first before moving on to 200 grit and finally 320 grit sandpaper. Applying a coat of spray-on filler before sanding the 3D print will make the whole process easier and faster.

The reason why I recommend this method of smoothing 3D prints for most projects and especially for beginners is because it is the easiest method and you don´t require any hazardous liquids like Ethyl Acetate.

Here is how I usually sand my 3D prints.

First I use some rough grit sandpaper and files to smooth very rough parts.

Then I usually apply a spray-on filler to fill in any small uneven parts and to remove layer lines. You can get spray-on filler in your local hardware store in the paint section where the car paints are or right here on Amazon.

The filler is much easier and faster to sand which makes the whole sanding part less tedious and much faster.

I tend to work my way up to finer grit sandpaper. Usually, I will start with 120 grit, then move to 200 grit, and if I want the surface to be really smooth then I will sand the 3D print a final time with 320 grit sandpaper.

Finally, I will apply a primer to prepare the 3D print for painting. I have a whole guide on how to paint 3D prints including what kind of paint to use that you can read right here.

How to Smooth PLA Without Sanding

A lot of people find sanding very tedious and annoying and I completely understand that because I feel the same way. Luckily there are other ways to smooth 3D prints but they tend to involve hazardous liquids which is why I don´t like this method and why I don´t recommend it for most beginners.

As a whole, 3D prints can be smoothed by using either epoxy resin to fill in any uneven parts and print lines or by applying a solvent such as Ethyl Acetate to slightly melt the surface of the print which will smooth it.

I personally prefer using epoxy resin to smooth prints if I don´t want to sand the print.

Epoxy resin is liquid and will fill in any uneven parts in the print before hardening after about 24 hours. Once the resin has hardened it will be very hard and if you see any uneven surface details then you can still remove those by sanding them.

The alternative is using a chemical solvent like Ethyl Acetate, for example, or by misting the print with a chemical solvent.

I personally never use this method of smoothing the print because it is very hazardous and the outcome tends to lose some of its detail. But if you want to know how it is done then read this article from bitfab.io.

It doesn´t matter which method you use you should still apply a primer before painting the print to ensure that the paint permanently sticks to the surface of the print.

How to Efficiently Remove Layer Lines on 3D Prints

Probably the most annoying part about 3D printing is the layer lines. It doesn´t matter how well you adjust your 3D printer some layer lines will always be visible unless you are using a resin printer that is. So how do you remove these annoying layer lines?

To remove layer lines on 3D prints the print either has to be sanded, coated with epoxy resin, or the surface has to be slightly melted with a chemical solvent. The safest method is applying a spray-on filler and then sanding the print.

My personal favorite method is using a spray-on filler and then sanding the whole print to make it smooth and remove any layer lines.

Using epoxy resin to coat the whole print is also a viable solution but I only recommend this method for people that have experience with resin.

Using chemical solvents is by far my least favorite method as it usually leads to some surface details being lost and you have to handle quite hazardous liquids.

If you want to use this method however then consider reading this guide by bitfab.io.

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