3 Techniques For Supportless 3D Printing

I prefer to avoid using supports whenever I can. They are a frustrating part of 3D printing that can lead to print artifacts that need to be cleaned up in the post printing phase.

You can eliminate supports by choosing models that do not require them. Models with steep angles and short bridges work best. Use a 3D model editor to split models that otherwise would require supports. If possible, use a resin printer which can easily print shallow angles and overhangs without support.

Let’s discuss what to look for in a model to avoid needing to use supports.

Choose A Model That Doesn’t Require Supports

This technique will limit the models that you can print. But it will help you choose models that will successfully print without having supports that need to be cleaned up.

The important key is to know when supports are required for a model.

You will need supports for shallow angle and overhands on an FDM printer. Later I’ll discuss using a resin printer. For now, these are the factors we will look out for.

Some models might need support in their default positions but can be rotated to eliminate or reduce the need for supports.

Find Your Supportless Angle

Different printers have different angles at which they can successfully print without supports. It does not vary widely between printers but you will want to test your printer for what angles you can successfully print.

Just for clarification, the angle I am referring to is the angle from the z-axis so that 0° is straight up. When I started, I was confused by angles because I also thought of angles as from the build plate.

Note: The 45° rule. Any angle up to 45° should be able to print supportless on any 3D printer. Almost all 3D printers can print without supports higher angles. You can use this general rule if you don’t want to find the angle that your print is able to print without supports.

I recommend do some test prints to find which angles work best for your setup.

As with so many test prints, there is an overhang angle test print on Thingiverse.

Use the test print to determine what angles your printer is capable of successfully print without supports.

One factor that will impact how steep of an angle you can print supportless is the layer thickness. The taller the layer, the further out the next layer has to print in order to print a given angle. This means that thicker layers risk that the next layer may have to print beyond the current layer.

To make this more clear, if your layer height is 0.3 mm and you are printing at a 45° angle, the next layer had to stick out 0.3mm. When you are using a 0.4mm nozzle, your next layer has to lay a 0.4 mm line on a 0.1mm surface.

With a 0.2 mm layer height and 45° angle, the next layer only needs to stick out 0.2mm. It is much easier to layer 0.4mm onto 0.2mm than 0.1.

Bridges Do Not Require Supports

Sometimes you can get away with 90° angles.

Some models will have perfect 90° angles where the angle entirely exists between 2 points of the model. These parts are bridges.

Using bridging techniques, you can print these areas without supports.

2 conditions must be met for bridging.

First, points on both sides of the bridge must attach to areas that are able to successfully print. In other words, the layers below the layer with the bridge needs to be able to print successfully.

Secondly, the lines that connect both sides of the area that is bridging must be straight lines. Bridging cannot work if the bridge is in any way curved.

The shorter the bridge, the more likely to print successfully. You will want to test you bridging settings using a bridge test print from Thingiverse.

Using the bridge test print, you can have a good idea how long of a bridge your printer can successfully print.

To successfully bridge the printer needs to pull on the filament as it extrudes. If the filament is too liquidy, the lines will droop.

Set your temperature on the lower end of the temperature range. The higher the temperature, the more liquidy the filament will be. For PLA, print closer to 180°C.

While temperature has to be set for the entire model, there are some settings that can be changed for bridging.

Cura has experimental bridge settings that you can use. There are several settings that can help with bridging that you might not want for the entire print.

If you cannot find the bridge settings, use the search settings feature to search for bridge. All the bridge settings are in the Experimental group and are hidden by default.

Click Enable Bridge Settings. The default settings are provided. These may not be optimal for you.

I recommend that you increase the speed settings. These settings are set low on the assumption that bridging requires slow printing. My self and other have found that bridging can be just as effective at 30mm/sec or 60mm/sec.

Your mileage may vary.

Bridge Fan Speed is one of the settings you will want to focus on. Fan speed should start at 100% but if you have clogging problems, lower this setting in 5% increments. The advantage of having this setting just for bridging instead of using the general fan speed is that you can reduce issues like clogging or layer adhesion problems that can be caused by constant 100% fan speed settings.

Bridge Wall Flow and Bridge Skin Flow are also settings to tweak. 50% and 60% may be too low so you might want to start at 90%. These control the amount of filament. Since we want to avoid too much filament coming out too fast, lowering the flow can help reduce sagging while bridging.

Rotate The Model

In Cura, you can easily rotate models to their side using the rotate button. The third button that pops out from rotate allows you to select a face to align to build plate.

Sometimes what looks like a flat surface is a combination of surfaces. This means that when you select a surface to align to the build plate, you can get unexpected alignments. You may have to try multiple places on the surface to get it to align properly.

Embed Supports In The Model

If you are designing a model, you can embed supports as part of the model. These embedded supports are intended to be part of the model.

These could be swords that touch the ground to support a hand or a cape that support the back of a model.

Rocket Pig Games does a great job with their miniatures to creature models that do not need supports.

If you have any 3D modeling knowledge, you can take existing models and modify them by embedding supports in the models.

For those of you who are interested in learning to model in 3D, check out the courses available at SkillShare. SkillShare offers a variety of 3D design courses for different software packages. Get started with a 7 day free trial.

Split The Model To Avoid Supports

With a little bit of patience, you can use 3D modeling software to split an existing 3D model into multiple parts to print without supports. Sometimes it is just as easy as splitting a model in half down the middle.

The software I use to edit models is Meshmixer.

You can also use Slic3r to split models. Slic3r can split the model along either the X, Y or Z-axis. Since you can rotate a model, these split options may be good enough.

Since Slic3r will slice completely though the model, you might slice through other parts of the model at the same time. Meshmixer, on the other hand, will allow you to make splits on model segments.

I had tried to split off the wings of a dragon model with Slic3r and kept slicing through the base or the tip of the wings at the same time. Using Meshmixer, I could have avoided this problem.

Here is a model that I will demonstrate how to print without supports.

This is a model of a Star Wars Tie Fighter. No matter how you orient this, it will require supports if printed on an FDM printer. You might be able to get away with printing this on its side with a resin printer, but area that would be on the build plate is very small and it likely wouldn’t hold.

Splitting In Slic3r

This model can be easily split in Slic3r. We want to make a cut along a horizontal plane, right through the middle.

Select the model to be cut in the Slic3r interface and click the Cut.. button at the top.

A new window opens up showing the model. Check to keep the upper and lower parts. Make horizontal plane that will cut the model makes the cut exactly where you want it. By chance, the Tie Fighter model defaulted to an almost perfect placing of the cutting plane.

If the cut you need isn’t exactly in the middle, adjust the height using either the slider or manually entering the z-height. If you want to make a cut along a different axis, you can change that in the drop down menu.

This model actually has 2 blasters on the front so cutting it along the X-axis so that the blaster print pointed up makes the most sense.

Here is the final cut pieces.

You can save the separate cut pieces one at a time by selecting one piece and clicking Object > Export object as STL… You can also just select Export G-Code.. if you are ready to print.

Splitting In Meshmixer

To make the split in Meshmixer, you have to import the model. When you open Meshmixer, you can click the Import button and select the model. You can also go to the File menu and select Import.

Click the Edit button and select Plane Cut to bring up the cutting plane. This plane can be rotated and moved to slice where you need.

Click and drag the arrows to move the plan around. The straight arrows move the plane along the axis they point and the curved arrows rotate the plane.

You can also define a custom plane by holding down the left mouse button.

Once you have split your model, you will need to separate the pieces. Go to Edit and select Separate Shells. Your model may separate into more than 2 shells. The Tie Fighter separated into 6 shells. The wings were separate from the cockpit and each of these was split when I made the cut.

You can reattach separated pieces by going to the View menu and selecting Show Objects Browser. If you see more than 2 objects, your original object already had multiple shells. Hold the Control key on your keyboard and select the pieces that should be attached. A new menu will pop up with the option to Combine.

Select one of your pieces and click Export to export the piece to an STL file. Select the other piece and export that as well. Now you have a 2 files that can print without supports.

Use A Resin Printer

A resin printer can successfully print a 90° angle.

This means that resin 3D printers are much more flexible in printing without supports.

Resin printers are my preferred method of printing minis. This figures often have very shallow angles that would require supports but are often so small that it is hard to find support structures that can be used that don’t damage the model when they are removed.

The reason that resin printers can print 90° angles is because they print the entire layer all at once. And since the layers are always hardened before the next layer is printed, there is no soft filament that can droop.

Resin printers are not a guarantee of supportless printing, however.

In order to print without a support, every part of the print must be attached to a previous layer. Any part that hangs down, like fingers or a chin on a D&D mini, will still require supports.

Give Up And Just Use Better Supports

Some models just cannot be printed without supports.

These are models that would require too many splits or are too difficult to split.

There are ways that you can create better supports.

Use Dissolvable Supports

To use dissolvable supports, you need to have a way to print 2 different filaments.

I highly recommend only using printers with multiple hotends and nozzles rather printers like the Geeetech A20M that allow you to print 2 different filaments through the same nozzle.

If your multi-filament printer has only one hotend, you risk mixing the dissolvable filament with your other filament. Any part that is a mix will partially dissolve during support removal.

The most common type of dissolvable filament is PVA. PVA is biodegradable and dissolves in water. This filament is best used with PLA and not ABS. It adheres better to PLA and prints at similar temperatures. Monoprice PVA is available on Amazon.

If you are printing with ABS, you will want to use HIPS filament as a dissolvable support. The biggest disadvantage of HIPS is that is requires limonene to dissolve. Take a HIPS supported model and dip it into a 50-50 mix of limonene and isopropyl alcohol to dissolve the supports. You can get HIPS and limonene through Amazon.

Despite the significant cost different between PVA and HIPS, I recommend using PVA. You will save more money using the water as a solvent then you save by buying a roll of HIPS. But you will need HIPS if you are printing ABS.

Improve Support Settings

If you cannot use dissolvable supports, you may just need to optimize your support settings.

There are 4 settings that influence the effect that supports have on your final print.

Printing Temperature

If the print temperature is too high, the fillament will be too liquidy. This will result in the print sticking too much to the supports.

If you are printing with PLA, print between 180 and 190°C. If you need to print at higher temperatures for other reasons, try to keep the temperature as close to 190°C as you can.

Enable Support Interface

The interface is a border between the print and the supports. The interface protects the print from the sparse support pattern from leaving marks on the print.

Without an interface, the supports will directly touch the print. If you are using a zig-zag support pattern, you will see a zig-zag pattern on the print.

With an interface, there are one or more layers printed on between the support structure and the main print. This helps ensure that you get a size smooth print without support marks.

This setting should be checked.

Support Interface Thickness

If the interface is too thin, the interface layers will stick too easily to the print. An interface thickness of between 0.6 mm and 1.0 mm will tend to reduce the likelihood of the interface sticking.

Support Z Distance

This is the distance between the interface layer and the actual print. If the interface is too close to the print, it will stick.

If the interface distance is too large, the support will fail in its purpose.

The best distance is around 0.2 mm. This will keep a sufficient distance to prevent the interface from sticking to the print but close enough that it will still support the print.

Recommended Settings

Printing Temperature180 – 190 °C
Enable Support Interface
Support Interface Thickness0.6 mm – 1.0 mm
Support Z Distance0.2 mm

Verl Humpherys

I have been 3D printing since 2017, using both FDM and SLA printers. My prints have varied from small D&D figurines to full sized baby Groot. I printed mounts for my various game consoles and my Oculus Rift. Any problem you can have with a 3D printer, I have had. And I am here to tell you what I have learned.

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