In the realm of 3D printing, makers often face a significant hurdle when attempting to bring 2D images to life in vibrant, multi-color prints.

In recent years, the field of multi-color 3D printing has seen many solutions emerge, as numerous 3D printer manufacturers have launched printers equipped with multiple extruders or automatic filament management systems. With these types of printers, makers can create 3D-printed works with up to a dozen colors. However, the more colors that can be achieved, the higher the cost of the 3D printing device and filament tends to be.

Furthermore, in the current landscape where CMYK 3D printing technology is not yet widely accessible, even owning a 3D printer capable of creating 16-color prints may not suffice to turn 2D images into finely detailed, color-accurate prints with varied lightness, tones, and shades. This is largely due to the relatively limited variety of colors available in the filament market, making it challenging to achieve this goal.

But today, we're going to show you some magic by introducing HueForge, a software that creates richly hued, painting-like reliefs from 2D images, even with just two colors. More importantly, this technique works well with all the Snapmaker 3D printers—Snapmaker Artisan (Dual Extrusion), Snapmaker J1/J1s (IDEX), and even the Single Extrusion Models like Snapmaker 2.0 and Snapmaker Original.

Before we jump into the exciting tutorial, let's first get more specific about HueForge.

How HueForge Works

As introduced on its official website, "HueForge is software which allows you to create detailed multi-color 3D Prints using only Swap-by-Layer through a process we call Filament Painting".

To put it more explicitly, HueForge achieves multi-color design through the layering of filament. The question then arises: how do we, or HueForge, know which filaments can exhibit different color effects when stacked, and which are more easily able to show varied color effects through layering?

This brings us to the concept of Transmission Distance (TD). For example, many painting software applications allow users to set the transparency of brush colors. When transparency is set to 0%, layering the same color multiple times does not result in any variation in shade. However, when transparency is set above 0%, repeating the layering process makes the color on the canvas progressively darker, until it matches the color with 0% transparency.

Similarly, the higher the TD value, the higher the "transparency" of the filament shown in the print, making it easier to achieve a richer depth of color through stacking, either by itself or with other filaments. Vise versa.

Filaments produced by different manufacturers often have different TD values, and the stacking of the same filament, different filament, or different colors of filaments can all result in a variety of richer colors and shades.

It is also because HueForge achieves multi-color design through filament layering that it can convert a 2D image into a 3D printable relief model. Therefore, to accurately set and preview the visual effects of relief models in HueForge, it is necessary to specify the correct TD values of the available filaments. To facilitate user operation, HueForge includes a vast library of filaments covering many mainstream manufacturers' products, with corresponding TD values that have been tested and can be directly applied. For filaments not in the library, HueForge also provides a simple method for testing the TD value, which is detailed in the third section of this article.

In short, once you import a 2D image into HueForge and set the TD values for the filaments to be used, you can design a unique relief model by adjusting the number of layers and the layering order of different filaments.

Sample Tutorial

Now that you have a basic understanding of how HueFore works, let's practice using our sample image with your Snapmaker right away! The tutorial will be completed using the Snapmaker Artisan 3-in-1 3D Printer and the Dual Extrusion Model, while the process and steps are compatible with other Snapmaker printers.

You can use our recommended settings or make any adjustments to create your unique relief from it.

Step One: Create the Relief Design with Hueforge

1.   Download Hueforge.

       You can purchase and download HueForge from its official website.

        HueForge is compatible with Windows and MacOS 11+, and there are several pricing plans available for different usage needs.

2.   Download and import the sample image into HueForge.

       Sample Image.png  

       Drag the file into the interface of HueForge or click File > Open File > Image in the top menu to import the image.

       After the image is successfully imported, the relief preview (on the right) will be displayed next to the imported image.

       By default, the preview consists only of black, grey, and white colors, which you can change in later steps.

        HueForge supports images imported in the formats of PNG, JPG, JPEG, and WEBP.

        If you want to create reliefs without a background, you should first remove the background from the original image using graphic processing applications like Photoshop before importing it into HueForge.

3.   Specify the parameters of the relief.

           ⅰ. In the General Options and Operations panel, adjust the basic parameters of the relief. 

              Our recommended settings are shown in the picture (except for the width and height, which you can adjust according to your own needs).

           ⅱ. In the Model Geometry panel, adjust the geometric parameters of the relief. 

                Our recommended settings are shown in the picture. We only modified the Min Depth to 0.48 and the Max Depth to 4.00, while you can also try experimenting with other parameters on your own.

4.   Select the filament used to print the relief.

      On the Filament Library panel, drag the color icon of the selected filament to the slider in the Color Sliders panel. The colors we use are black, green, red, orange, yellow, and white.

        If the filament you own is not listed in the default library, you can also add new filament and test

        You can use filaments in the recommended colors above if they happen to be at your hand or use filaments in any other colors that you prefer and that are available around.

5.   Tweak the visual effect of the relief with the color sliders.

       In the Color Sliders panel, move the sliders up and down to change the layering of filament.

       Our recommended settings are shown in the picture (except for the TD values, which vary with filament and require additional testing for filament not listed in the default library).

        High-TD white filament can be used as a smoother for color or brightness, generally placed between two colors that need to be smoothed.

6.   Generate the key information.

       In the General Options and Operations panel, click Describe.

       A window will pop up displaying key information needed for slicing: layer height, initial layer height, filament info, and most importantly, the filament swap instructions. You can either click to copy the information elsewhere convenient for later use, or click to generate it again when needed.

7.   Export the STL file.

       In the top menu, click File > Export STL to export the STL file for slicing.

Step Two: Configure the Parameters with the Slicer

       To demonstrate how to add the M600 command (for filament changing), we will use PrusaSlicer for slicing.

1.   Import the STL file and adjust the slicing parameters.

ⅰ. In PrusaSlicer, import the STL file, click Print Settings, and switch to the Advanced mode.

           ⅱ. Adjust the parameters as specified below, as they are necessary for a successful relief print:

1. 1. • Perimeters: 1
      • Fill density: 100％
      • Fill pattern: Rectilinear
      • Top fill pattern: Monotonic Lines
      • Bottom fill pattern: Monotonic Lines
      • Detect thin walls: On

            ⅲ. Check and make sure that the layer height and the first layer height set in the slicer are consistent with the Layer Height and Base Layer already set in HueForge.

            ⅳ. Set the Black filament (or the "start with" filament described in the key information, as shown below) as the default filament for the model.

2.   Add the filament changing command (taking our HueForge configurations as an example).

           ⅰ. Click Slice now. It might take a while for the G-code preview to display.

            ⅱ. Along the layer bar on the right, find and click Layer 12 (1.16 mm).

            ⅲ. Right click the plus sign that appears beside, click Add color change (M600) for: and select the Extruder 1 to add the filament changing command at that layer.

            PrusaSlicer does not support the settings for the Dual Extruder Module. Therefore, you have to use one of the two extruders, which you choose to heat by operating on the Touchscreen, to print the entire relief.

           ⅳ. Along the color selection window, change the color to Green.

            ⅴ. Click Slice now to save the added command.

            In the following steps, each time after you add the command and change the color, be sure to click Slice now to save the settings.

            ⅵ. Along the layer bar on the right, find and click Layer 16 (1.48 mm).

            ⅶ. Add the M600 command and change the color to Red.

            ⅷ. Along the layer bar on the right, find and click Layer 25 (2.2 mm).

            ⅸ. Add the M600 command and change the color to Orange.

            ⅹ. Along the layer bar on the right, find and click Layer 33 (2.84 mm).

            xi. Add the M600 command and change the color to Yellow.

            xii. Along the layers bar on the right, find and click Layer 38 (3.24 mm).

            xiii. Add the M600 command and change the color to White.

      In this way, the printing will pause at the layer where the M600 command is added so that you can manually change the filament.

3.   Double-check all the settings.

           ⅰ. Check if the key slicing parameters are specified as required.

            The commands you have added will be saved even if you switch to the Print Settings tab.

            ⅱ. Click Slice now again.

            ⅲ. In HueForge, click Normal in the General Options and Operations panel to switch to the slicer preview mode, and check if the preview looks the same (or almost the same) as the G-code preview in the slicer.

4.   Export the G-code to the printer and start printing.

5.   Manually change the filament when the printing pauses as configured.

            ⅰ. After the printing pauses at a specific layer, tap on the Touchscreen to set the temperature of the working nozzle to 200℃.

            ⅱ. After the nozzle is heated up to 200℃, manually unload the filament.

1. 1. 1. Open the front cover of the toolhead.
      2. Press the extruder buckle downwards to expand the dual-gear extruder.
      3. Pull the filament out of the toolhead.

            You may need to use a little force or heat the nozzle to a slightly higher temperature to assist the unloading.

            ⅲ. Manually load the new filament.

1. 1. 1. Insert the filament into the toolhead until it is pushed right into the feed hole of the hot end and is extruded from the nozzle.
      2. Gently push the filament down until the old filament is completely extruded out and the new filament runs out smoothly.
      3. Press the extruder buckle back in place and close the front cover.

            ⅳ. On the Touchscreen, tap to resume printing.

            ⅴ. Repeat the above steps each time when the printing pauses as configured.

How to Test the TD Value of Filament

Testing the TD value of the filament used to print the relief is very important, as it relates to whether the relief preview you see in the HueForge matches the actual printing result. You can take the following steps to conduct the test.

1. In the local directory of HueForge, locate the Step_Test_Sqaure.stl file in the Tools folder and import it into HueForge. The interface should display as below.
2. In the Color Sliders panel, adjust the first four sliders to match the ones displayed in the picture.
3. At the bottom of the Filament Library panel, click New Filament to add the filament you want to test.

4. Take a photo of the filament in a well-lit environment and use the eyedropper tool to extract the color of the filament from the photo.
5. In the Add Filament window, specify the necessary information about the filament. You can keep the TD value at its default setting for now, as it won't have any impact on the testing result.
6. Click and drag the color icon of the newly added filament into the second slider to replace the default grey color.
7. Export the STL file, configure the settings in the slicer, and print the model out.
8. In HueForge, adjust the TD value of the tested filament in the Color Sliders panel until the relief preview looks as close as possible to the print.

Useful Tips for Large Prints

For large-sized prints, you can increase the success rate of printing by following these tips:

• Adjust the first layer height appropriately. For example, when printing objects with a horizontal or vertical size of 300 or 400 mm, you can set the layer height as 0.2-0.28 mm (just for reference).
• Turn off the part cooling fan during printing.
• Preheat the heated bed to the target temperature for 15-20 minutes before printing to stabilize the bed deformation. It is also recommended to raise the bed temperature appropriately (to 70-75°C, for instance).
• Wait until the first layer is printed successfully before leaving, as it can take some time to read the file before printing, during which the temperatures of the nozzle and heated bed may decrease.
• Adjust the height of the working nozzle as necessary to enhance the first layer printing result.
• If there are strings on the print, you can reduce the nozzle temperature by 5-10℃ to improve the print quality.
• If you are using Snapmaker Artisan:
  • After preheating, calibrate the Z offset of the left and right nozzle, and use the right nozzle to calibrate the heated bed (either at 25 or 81 points).
  • When heating and loading the nozzle, make sure to heat the heated bed simultaneously to avoid sudden drops in the bed temperature.
  • Use the glass side of the build plate and apply printing adhesives.

Learn more about Snapmaker Artisan 3-in-1 3D Printer.

Whether direct drive or Bowden, different extruders work pretty much the same way — the filament is inserted into the extruder, and the motor and gears drive it into the hot end, which will then use electrical heating (e.g., resistance heating) to melt the filament. Finally, the liquified material is evenly extruded out of the nozzle onto the heated bed, stacking up layer by layer to form a 3D object.

Most printers only have one extruder, while some have two. So, which is better — single or dual? If your pocket is deep enough, two is better than one for the most part. In fact, dual extruder 3D printers have become more and more common in recent years, and are even trending to replace single-head printers.

Why are dual extruder 3D printers trending?

Dual color or material combo

Dual extruder can print objects using two different filament colors or types on the same print. This allows more complex and colorful prints.

Snapmaker Dual Extrusion 3D Printing Module mounted on Snapmaker 2.0

Two-color printing is not that uncommon. Even with a single extruder, similar effects can be achieved by manually changing the filament. However, if you want to use two different materials on the same object, for example ABS and TPU to print a flexible/rigid combined object, manually changing filament can be very troublesome, and is prone to failed prints because optimal settings for the two materials are different. Rather than risking it with great effort, it's better to just print them separately and glue them together.

In contrast, when using a dual extruder printer, you can set different parameters for each extruder directly in the slicer software, and complete dual material printing in one print job.

Breakaway and soluble support

The ability to print easily detachable (or “breakaway” as a trade name) and soluble supports is perhaps the primary reason most people buy a dual extruder 3D printer. Removing supports after printing can be tedious and time consuming. And if you don’t do it properly, your print can be ruined by marks, pits, divots or blemishes on the surface finish.

Breakaway support

Breakaway support materials are formulated to have low interlayer adhesion and be mechanically brittle, so they break away cleanly with little force. Soluble materials can dissolve in water or other solvents. PVA (Polyvinyl Alcohol) is the most commonly used one. It is highly sensitive to moisture and decomposes when in contact with water. Taking advantage of this property, it can be used as a support material to fill some difficult-to-reach geometries that allow liquid to flow into. After printing, soaking the print in water dissolves away the supports, leaving behind a smooth printed surface.

Soluble support

Some additional functions

Dual extruders also enable some additional functions, such as a backup mode. In single-extrusion printing, if the active extruder fails or clogs, or the filament runs out, the idle extruder can take over and finish the remainder of the print. This improves overall uptime and reliability.

Improved slicing software

It is mechanically simple to build a dual extruder system by just duplicating parts, but the real challenge is in the software. The popularity of dual extruder goes hand in hand with improvements in slicing software. The slicing algorithms are better at planning optimal toolpaths for dual extruders to minimize travel moves and retracts. They also do well in assigning different model parts to be printed by each nozzle to maximize use and minimize idle nozzles. Software advancements have made dual extruders more user-friendly and reliable, allowing wider adoption.

Drawbacks of Dual extruder

With the growth of the 3D printing industry, desktop printers are more affordable and easier to use nowadays. Dual extruder has also become a common feature on many budget products, allowing more users to experience the benefits of dual printing. However, dual extruders also have some flaws:

Source: Simplify3d

• Cross contamination and collision: In dual-color printing, the idle extruder can ooze material due to residual heat and cause contamination when it glides over the printed part, or even bump into it if the nozzle is too low.
• More maintenance: Twice the hot ends means twice as many parts to check, clean and replace when there are jams or clogs.
• Relatively smaller build volume: Since the extruders themselves take up some length on the X axis, dual-head printers will have a smaller build volume compared to single-head given the same printer frame size. This is especially noticeable when upgrading from single to dual head.

The maintenance and build volume drawbacks are probably unavoidable, but contamination and collision can be solved. The most common way to deal with contamination is setting retraction in the slicer, which prevents oozing by temporarily reversing the filament in the extruder during travel moves.

Another method is using a prime tower — printing another object concurrently with the main print, giving oozing or leaking inactive nozzles a place to purge material instead of on the print. Similar solutions include ooze shield, which surrounds the printed part so any oozed material gets wiped off on the shield when the nozzles are close to the print.

Ooze shield (Source: IceSL)

Some printers also have a wiping device installed directly on the machine at the same height as the nozzle, so the nozzle can wipe off any residual when passing over it. Simple yet practical.

Snapmaker J1s's nozzle wiper

However, these don't solve the collision issue, and prime towers/ooze shields increase time and material usage. In comparison, mechanically lifting the inactive extruder seems more versatile. For example, the Snapmaker Dual Extrusion Module uses motors to automatically raise/lower the extruders, avoiding both contamination/collisions, and allowing fast, quiet extruder switching.

Auto extruder lifting of Snapmaker Dual Extrusion Module

Finally, there is the ultimate solution — an IDEX (Independent Dual Extruder) 3D printer. As the name suggests, the two extruders can move independently. When printing with one head, the other can park inactive in a corner with no need for heating. When both are active, they print independently with no interference. However, to further reduce ooze impacts, IDEX printers may still employ wiping devices, retraction, prime towers, etc. during dual extrusion printing.

Independent v.s. dependent dual extruder system

IDEX has some advantages over regular dependent dual extruders, but also poses some challenges for manufacturers and users.

Snapmaker J1's printing in duplication mode

Advantages

• Minimal contamination and collision: In dual printing, the idle extruder parks in a corner rather than moving along with the active extruder. And before the next printing job, the extruder can wipe off any oozed material using a wiping device or prime tower. So IDEX can effectively eliminate ooze contamination and collision issues.
• Mirror and duplication printing: IDEX printers can double the productivity by printing two mirrored or identical objects simultaneously. Very useful for mass-producing small items like chess pieces.

• Less weight and higher accuracy: Compared to a mechanically linked dual extruder, one single extruder of an IDEX printer is lighter, allowing faster moves with less floating mass and higher accuracy.

Disadvantages

• More difficult to manufacture: Precisely aligning the independent extruder carriages and extruders demands tight manufacturing and assembly tolerances.

• Trickier calibration: Calibration is one of the biggest challenges in IDEX printer design. The two independent extruders not only need to be calibrated with the bed, but also to each other in the X, Y and Z axes. Poor calibration can cause cracks or even print fractures due to poor layer adhesion.

• Higher cost: IDEX not only has higher R&D costs on software, but also requires an independent or semi-independent motion system on the hardware side, including motors and carriages for each extruder. If not sharing an X-axis, additional linear rails, leadscrews or belts are also needed. These factors mean IDEX printers generally cost more than regular dual extruders.

How to choose from single extruder, dependent dual extruder, and IDEX

Here are some things to consider when making the choice:

Single Extruder

• Simplest and most affordable option;
• Easier to calibrate and maintain;
• Limited to single color/material prints.

Dependent Dual Extruder

• Dual color or material printing without much filament waste;
• Allows dissolvable and breakaway supports;
• Costs more than single extruder;
• Potential collision risks and idle oozing issues;
• Trickier calibration.

IDEX

• Can print identical or mirrored objects twice as fast;
• Dual color or material printing without much filament waste;
• Allows dissolvable and breakaway supports;
• Minimal risk of collisions or ooze;
• Highest cost and calibration needs.

In general, for most hobby printing, a single extruder is sufficient. For two color prints or easier support removal, consider a dependent dual extruder. For advanced applications or speed, an IDEX system may be ideal if budget allows. Hope you can find your dream printer!

3D printing technology is advancing by leaps and bounds. One moment we are discussing making small toys to entertain children, and the next second we see news that a 3D printer has built a concrete building that can withstand an 8-magnitude earthquake. Given time, "3D printing a 3D printer" also seems possible.

But leaving prospects aside, what hobbyists and makers care more about are still desktop 3D printers — what types there are, how fast they print, and how much they cost. If you like getting to the bottom of things, or ever tried DIYing a 3D printer before, you must also have pondered this question: how do they move?

XYZ, I3 and CoreXY are currently the most popular styles of desktop 3D printers. This is how they move: the machine has one or several axes in the X, Y and Z directions of the 3D coordinate system. One end of each axis is equipped with a motor to provide power. Synchronous belts or leadscrews then convert the motor's rotation into linear motion along the X, Y and Z directions. Finally, with the linear guide rail systems in the 3 directions, the machine can position the nozzle at any point in the 3D space formed by the axes, extrude the filament, and create a 3D object.

Linear guide rail system on Snapmaker Artisan

Why are guide systems important?

The guide systems mainly serves 3 purposes during printing:

• Precision: Realize tight tolerance, prevent wobble, and ensure the print head or heated bed installed on the guides moves linearly along the predetermined direction;
• Smoothness: Reduce friction with bearings or rollers, and contribute to smoother motion;
• Reliability: Guiding structures with excellent rigidity can improve machine reliability and contribute to more consistent prints over time.

The variety of guide systems

In general, the guide systems used on 3D printers include:

• Wheels & profiles
• Linear rods & bearings
• Linear rails
• Embedded linear rails (introduced by Snapmaker)

Wheels & profiles

Source: Kywoo3D

Among all the guides, the combination of wheels and profiles is probably the most common and cost-effective. There are typically 3 to 4 rollers running along the V- or T-shaped groove of the profile to guide the movements.

POM wheels

Source: Printer Mods

The outer ring of the wheels is most commonly made of POM (Polyformaldehyde), and the inner ring is made up of steel and ball bearings. POM has high strength, low deformation, and excellent abrasion resistance, making it especially suitable for making printer wheels. With proper use, POM rollers can last hundreds of hours. Some manufacturers also use PC (Polycarbonate) to make wheels, which have even higher strength and longer life, though at a slightly higher price.

PC wheels

Source: I3D Service

To ensure linear motion, the wheels should grip the profiles properly. Too loose and vibration can occur at high speeds. Too tight will increase wear — accumulated debris can pile up between the wheels and rails, causing bumpy or jittery motion. So users need to adjust the wheel tightness based on how the printer works, clean debris, and replace wheels when necessary. Compared to other guides, the wheel and profile combo requires more frequent maintenance.

Additionally, plastics have lower rigidity than metals. Wheel deformation during motion is hard to avoid, so printers using wheels generally have lower precision compared to those with steel guides.

V-slot profile

Source: 3D Printing Store

The profiles commonly used on 3D printers are available in two types: V-slot profiles and T-slot profiles. As the names suggest, the main difference between them is the cross-sectional shape. Different profiles pair with different wheels to achieve good guiding effects.

Since the profiles are customizable, inexpensive, and with sufficient performance, the combination of wheels and profiles is the top choice for many DIY 3D printer builds.

Advantages

• Good guiding performance, cheap and useful;
• Abundant options, widely available;
• Easy to install, use, and modify;

Disadvantages

• Lower precision;
• More prone to vibration;
• Requires more frequent maintenance.

Linear rods & bearings

The limitations of wheel and profile guides have led DIYers and manufacturers to shift more attention to another combination with superior precision and stability — linear rods and bearings. In the past few years, rod and bearing guides have become almost synonymous with guide systems for 3D printers. At least 2 rods and 2 bearings are needed for each axis of the printer. The bearings either wrap or cling to the rods, while connecting to carriages mounted with an extruder or heated bed, to guide the linear motion.

Linear rods with linear bearings

Source: Amazon

A linear rod, aka smooth rod, is simply a cylindrical steel rod, available in various sizes — 3D printers typically use 8mm diameter ones. Rods can be machined to high dimensional accuracy with very smooth surfaces. Paired with ball bearings, properly assembled rods can achieve fairly good linear motions.

And yes there are also drawbacks of being smooth. When used for guidance, the rods need to be fixed at both ends with metal clamps. Also, bearings can not only move linearly but also rotate 360° around the cylinders. That's why they need to be attached to bearings on another parallel rod to let the extruder or heated bed move linearly. Parallelism between two rods can be challenging, especially for DIYers.

So, using shaft guides means higher precision and stability on one hand, but also larger footprint and weight, along with higher assembly difficulty on the other.

Snapmaker 2.0 Linear Module sectional view (linear rods in dark grey; U-groove bearings in yellow)

The bearings used with rods are mainly U-groove bearings and linear bearings made entirely of steel. U-groove bearings resemble wheels that can roll along the rods. Linear bearings have a cylindrical sleeve on the outside, with several rows of balls on the inside that can cycle along the shaft. Both can accomplish smooth guidance with minimal friction.

Rods and bearings are long lasting, only requiring occasional cleaning of buildup on the rods and lubricating the bearings. If the rods are enclosed in a housing instead of acting as the frame (e.g. Snapmaker 2.0's Linear Modules), disassembling the housing and lubricating the bearings is straightforward. However, replacing worn out bearings after prolonged use can be slightly tricky.

Advantages

• Excellent guiding performance, high precision, moderate cost;
• Abundant options, widely available;
• Low maintenance frequency;

Disadvantages

• Larger footprint and weight when enclosed;
• Parallelism can be a problem;
• Replacing bearings can be tricky.

Linear rails

Linear rail, also referred to as linear guide, has been trending in recent years. The steel rail part has a track on each side, and the sliders nested on it contain 2 sets of ball bearings that can cycle along the tracks. In addition to industrial 3D printers, more and more desktop manufacturers are also using linear rails in their high-end product lines, such as Snapmaker's J1.

Source: Adafruit

Although both are made of steel, when it comes to actual work, linear rails are less susceptible to bending and vibration compared to rods. This is mainly attributed to their unique mounting method. Rods are only fixed at both ends, while linear rails have mounting holes at regular intervals on the surface, allowing them to be tightly secured to the housing or other support structures.

This ensures stable linear motion and improves print quality on one hand, and increases the speed limit by preventing excessive shaking at high speeds on the other. This is one of the reasons J1 can achieve high-speed printing.

Snapmaker J1 IDEX 3D printer with linear rails

During assembly, linear rails can guide a single axis without pairing, saving space and weight to make the machine more lightweight and compact. There is also no need to worry about rail parallelism.

Source: Birailmotors

It all sounds great, but what's the catch? The price. Rough calculations show that while the sliders for linear rails have similar prices to the bearings for rods, the rails themselves cost about 2.5 – 4 times that of a pair of rods at equivalent lengths. In comparison, rods are cheap and good enough. Weighing the extra cost against performance gains, most DIYers would still opt for rods and bearings.

For maintenance, linear rails are similar to the former, requiring regular lubrication of the bearings. Exposed rails also need occasional cleaning.

Advantages

• Very high precision;
• Supports high-speed printing;
• Small footprint, convenient to use;

Disadvantages

• Cannot serve as support structures, needs to be installed on profiles, etc.;
• Expensive.

Embedded linear rails

Instead of using the above guides directly, some manufacturers, for the purpose of advancing technical capabilities or catering to specific products, are also exploring better solutions. Embedded linear rails are what Snapmaker chose for its Artisan model.

Snapmaker Artisan with embedded linear rails

The core strengths of linear rails lie in the high rigidity of the steel rails and the precise, smooth motion enabled by the ball bearings. These advantages are preserved in embedded linear rails.

When making the Linear Modules, Snapmaker embeds two steel strips into the inner walls of the aluminum alloy housing, then CNC grinds the steel precisely into rails with micron-level machining accuracy. Also, with the wider embedded rails, rigidity is further improved without increasing weight, better suiting high-power CNC operations — after all, Artisan is a 3-in-1 product, and ordinary 3D printers do not require such extreme rigidity.

Compared to directly mounting linear rails on the surface of extrusions, embedding the steel rails inside the linear modules prevents dust buildup on the rails, reducing maintenance frequency. It also makes the modules more lightweight and compact, so that an expensive machine does not end up looking like a DIY enthusiast's project. However, embedding linear rails does pose considerable manufacturing challenges for the producer, with no cost advantage over normal linear rails.

Advantages

• Same as linear rails: very high precision, supports high-speed printing, small footprint;
• Rail rigidity further improved;
• Lower maintenance frequency with rails enclosed;

Disadvantages

• Expensive;
• Not suitable for DIY.

Summary

	Linear rails	Linear rods & bearings	Wheels & profiles	Embedded linear rails
Precision	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐	⭐⭐⭐⭐
Rigidity	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐	⭐⭐⭐⭐⭐
Lifespan	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐	⭐⭐⭐⭐
Ease of use (in DIY)	⭐⭐⭐	⭐⭐	⭐⭐⭐	Can not be used for DIY
Maintenence frequency	😫	😫	😫😫	😫
Maintenance difficulty	😫	😫😫	😫	😫
Cost	💰💰💰	💰💰	💰	💰💰💰

Characteristics of TPU filament

TPU (thermoplastic polyurethane) is a soft resin that is resistant to bending, tension, and friction. And

it also has excellent chemical resistance. TPU is one of the most commonly used materials in 3D printers, because it can be used to make parts with rubber-like elasticity and impact resistance.

Advantages

• It is relatively inexpensive, easy to handle, and can produce parts with softness that cannot be obtained by the SLA printing method.
• Adhesion between layers is strong. By adjusting the wall thickness and infill, it is possible to make parts with various characteristics.
• Depending on the application, you can make soft parts like rubber tires or strong, unbreakable parts like gaskets and seals.

Disadvantages

• TPU is a material that easily absorbs moisture. Moisture absorption can cause bubbles or poor flow during printing, which can have a negative impact on products. Therefore, it requires more attention to storage and drying than other materials. For more information, check out this article: 3D Printing Filament Storage and Drying: Why and How.
• As explained in the next section, printing is technically more difficult than PLA. Supports are difficult to peel off, so it is necessary to create shapes that require as little support as possible.
• Like PLA, heat resistance is not good, so care should be taken.

Why is printing with TPU so difficult?

Differences in difficulty between different types of extruders

Proper pressure must be applied from the extruder to feed the filament out of the nozzle.

Bowden extruder used in some 3D printers has the advantage of having a small and lightweight head. But the long distance from the extruder to the nozzle makes it difficult to extrude TPU filament, which is soft and cannot be tensioned. Therefore, it is challenging to print TPU on a Borden-type 3D printer. Generally, higher temperatures, slower speeds, and avoidance of retraction are used.

The direct extruder used by Snapmaker allows the extruder and nozzle to be in close proximity to each other, allowing the proper pressure to be applied to even the softest TPU filaments. As a result, temperature and speed settings can be set to fit TPU, and retraction can be performed to enhance the quality of products. But still, printing with TPU is not easy.

Difficulties arising from the wide variation of TPU filaments

Like other filaments, TPU filaments come in a variety of types. In particular, Shore hardness is a characteristic measure of TPU. Generally, a smaller Shore hardness indicates softer material and a larger Shore hardness indicates harder material.

Even with the similar TPU materials, it is more difficult to print well than generic PLA because settings must be adjusted over the characteristics of the filament.

Troubles and solutions when using Snapmaker

Cannot extrude

Snapmaker direct extruder uses a combination of a single gear and opposite roller to extrude the filament. Soft TPU may bend in Snapmaker extruder and cannot be extruded properly, causing filament jamming.

• Lower the Printing Speed and Retraction Speed to increase the flow.
• It is recommended to use Polymaker TPU95-HF for TPU printing due to its high stiffness. 
• Carbon residue in the inner wall of the nozzle can lead to greater resistance. You can change the nozzle regularly.

Depending on the types of TPU filaments, Snapmaker may not be able to solve the problem. If the problem persists, please refer to the Snapmaker forum. You may find solutions from other users.

Deformation during printing

The flexibility of TPU allows for deformation during modeling due to the thin-walled structure of the structure and its own weight.

• It is recommended to modify the structure or add infill.
• Increasing the flow rate may prevent deformation. In this case, the molding object will be slightly larger.

Ragged object

Insufficient amount of extrusion tends to cause this problem. As well, too much or too fast retraction can cause a ragged object due to bubbles.

• Increase the extrusion flow. 
• Slow down the printing speed to secure the amount of extrusion per unit time.
• Reduce retraction distance and speed.

Note: Although it makes the product slightly stiffer, use the infill pattern gyroid for hollow structures to reduce the possibility of retraction.

Stringing

Stringing is one of the most common problems that occur when printing with TPU. It is difficult to completely avoid it due to its characteristics, but there are ways to reduce it as much as possible.

• Slightly decrease printing temperature.
• Accelerate travel speed.
• Enable Retract at Layer Change option.

Note: Increase retraction distance and decrease retraction speed are common answers, but they are inapplicable to Snapmaker due to mechanical differences, which would increase the possibility of filament jamming.

Unable to detach from the build plate

TPU has strong adhesion to the heated build plate. Depending on the print settings, it may be difficult to peel off the object from the print sheet.

• Use the Z offset to move the nozzle an extra distance (about +0.1 mm) from the build plate.
• Detach objects while the build plate is still heated with Pallet Knife. Be careful not to touch the hot surface of the build plate.
• Decrease initial build plate temperature.
• Use duct tape or masking tape to the print sheet.

Note: Generally speaking, a new print sheet provides stronger adhesion.

Snapmaker Luban settings

Here are some specific settings for Snapmaker Luban to solve the above problems.

Note: It is recommended to use Polymaker TPU95-HF for TPU printing.

Material settings

• Printing Temprature: 225℃
• Fan: ON
• Build Plate Temperature: 50-60℃
• Extrusion Flow: >120%
• Retraction Distance: 2.5mm
• Retraction Speed: 15mm/s 

Printing settings

• Layer Height: 0.1-0.3
• Initial Layer Height: >0.25
• Initial Layer Line Width: 150%
• Shell Thickness: >0.8
• Infil Pattern: Gyroid
• Printing Speed: <25mm/s
• Travel Speed: >70mm/s

Note: Typical settings can be downloaded here. Use these .json files on Snapmaker Luban. Click on the gear icon at the upper right, then click on the import icon in the bottom left corner of the settings. Check the image below.

Printing samples

Depending on your ideas, TPU has unlimited possibilities. Please enjoy Make Something Wonderful!

Crawler

Toy Parts

Fitted Lampshades

Flexible Toolbox             Speaker Sealing

Introduction

For many, the ability to print out nearly any object one could imagine from the comfort of their home is equal parts astonishing to inspiring. Now imagine if you could transform those relatively robust plastic creations into rigid long-lasting masterpieces. Well, I’m here to tell you that the process is surprisingly easy, and I’ll help guide you along every step of the way. Let’s get right into it, starting with the process overview, which details the key aspects of converting plastic 3D printed components into their concrete counterparts.

CAD Modeling: Turning the concept of your project into a three-dimensional object.

3D Printing: Converting the STL file into a tangible part, via additive manufacturing. 

Silicone Molding: Casting a negative silicone mold of the 3D printed parts.

Concrete Casting: Filling the negative silicone mold with concrete. 

Decorating: Arranging modular planters and adding decorative plants and materials.

How to Video

https://youtu.be/40XSeIGZyiU

Concrete Planters

Project Introduction

When I started this project, I wanted to design a modular planter that was able to be quickly configured into different arrangements. The design would have to be relatively minimalistic to ensure ease of 3D printing, silicon molding, and concrete casting. In addition to these design constraints, I wanted certain components to be stackable, adding another level of modularity to the system. 

Design Considerations

When I started the design of this project I wanted to have the ability to quickly rearrange the planters and pavers to create different layouts. I achieved this modularity by sub-dividing the base shape which was an elongated hexagon into 3 unique shapes. The main shape is a pentagon, which has three different configurations, depending on the application of that component. For example, if you wanted to create a vertical stack up, you would start with a base planter and then add as many hollow planters as you would like. Because these shapes are derived from the base elongated hexagon, they can be added in a repeating pattern to create new and unique shapes.

Figure 1.0: Base Shape constructed using four hexagon pavers.

Figure 1.1: Two examples of the different configurations that are possible with the modular components.

Bill of Materials

• PLA Filament
• Mold Star 30 Silicone
• Quikcrete Mix
• Potting Soil
• Decorative Filler Rocks
• Decorative Moss
• Succulents
• Hot Glue Gun
• 3D Printer
• 330-Grit Sandpaper
• 220-Grit Sandpaper
• Plastic Sheet
• Mixing Bowl
• Mixing Stick
  

CAD Modeling

The first step is turning the concept of your project into a three-dimensional version, which will allow us to export as an STL. This STL can later be processed by the slicing software, and we will get into that in the next step. 

Slicing and 3D Printing

Before we can begin printing, we need to first convert our STL file into G Code. This is carried out by the software Snapmaker Luban, which “slices” the models into thin layers and creates tool paths in the form of G Code, allowing the printer to interpret the data and turn the compilation of individual layers into a printable part. For a more detailed explanation of slicing and G Code, check out this article: Slicing and G Code: The Bridge Between 3D Model and 3D Printer. 

Figure 1.2: Slicing the hollow planter component in software Snapmaker Luban.

Post Processing

Once the printing process is completed, we can begin post-processing the components. Due to the geometry, most of the parts don’t need support material during printing and therefore most of the surfaces on the print are smooth. The only exception to this was the hollow planter, which could be printed in an orientation that would allow for no support material. However, I wanted the parts all to be oriented the same to ensure the fillet on the top surfaces was consistent. I started by sanding the parts using 220 grit sandpaper, this removed any major surface blemishes and gave the parts a relatively smooth finish. From there I applied filler primer to all the parts and let them dry. The filler primer did an excellent job filling in any small voids or gaps between layer lines. From there I sanded the parts once again, this time using 330 grit sandpaper, resulting in an almost perfectly smooth surface finish. Although sometimes tedious post-processing these parts is a key step in this project to ensure a high-quality finished product. Since the silicon mold will capture any small blemishes in the part, which will in turn be reflected in the concrete casted parts. 

Figure 1.3: Sanding filler primed hexagon paver with 330 grit sandpaper.

Mold Setup

Since I used a trial bottle of Mold Star 30 silicone I had to optimize the shape of the mold shell. I started by arranging the components I planned to cast in CAD and then designed the shell around them. Making sure to leave enough space between components to ensure the silicon mold hard rigid enough walls to support the concrete during curing. The mold shell was also 3D printed although, I didn’t post-process it at all since the surface finish on the perimeter of the silicone mold wasn’t important. The next step was to hot glue the post-processed prints to a base, I used a plastic sheet from an old picture frame. Then I placed the mold shell around those components and hot glued it as well. It’s important to make sure there are no gaps between the mold shell and the base, otherwise, the silicone will slowly leak out since it’s not very viscous. I didn’t use any mold release spray for this project, but you could use some if you wanted to ensure easy removal of the 3D-printed parts once the silicone cured. In my case, I was able to remove the parts with minimal work even without any release spray. 

Figure 1.4: All components and mold shell layed out and hot glued to plastic base.

Mixing Silicone

There were a few reasons I chose Mold Star 30 silicone for this project. The primary reason was that this specific silicone rubber doesn’t require a vacuum for degassing and has a low viscosity, which allows it to easily flow into small areas. To prep, the platinum silicones are mixed 1A:1B by volume, meaning no scale is necessary. I chose to pour each bottle into a common container and mixed them until a homogenous solution was achieved. Once the silicone was ready to be poured I slowly began filling the Mold shell, making sure to fill in all the little channels between the components and the shell. The last step in the silicone molding process was to agitate the silicone. This is a very important step, which removes any trapped oxygen bubbles within the silicone. If bubbles aren’t properly evacuated from the silicone, it will likely impact the surface finish on your final concrete parts once you cast the silicone mold. This could have been avoided had I used a vacuum chamber to degas the silicone, although I didn’t have one at my disposal. In the end, the features that were generated in the concrete parts due to residual trapped air bubbles ended up being a surface feature I came to appreciate and enjoy in the parts.   

Figure 1.5: Filling the mold shell with Mold Star 30 silicone. 

Component Removal

I started the component removal process by pealing away the flexible plastic base followed by pressing the silicone through the mold shell, leaving just the silicone mold with the entrapped 3D printed parts. From there it was as simple as pressing the 3D printed parts out since most parts were glued directly to the plastic base. Except for one part, which required me to add relief cuts to the silicon mold. These cuts would prove to be extremely useful once it came time to remove the concrete cast parts.

Figure 1.6: Silicone mold, once all 3D printed parts have been successfully removed.

Mixing Concrete

There is an expansive list of potential concrete mixes one could use for a casting operation like this. I opted for the Quikcrete sand/topping mix since the powder was relatively fine and I was able to easily source it from my local HomeDepot. The first step in mixing the concrete was to pour an appropriate amount of concrete powder into a mixing bowl, then added water. The general rule of thumb is to get the concrete to a consistency similar to that of oatmeal. You want the concrete to be wet enough to flow into the silicone mold nicely, but not too wet. When concrete is mixed with too much water it dries weaker, overly porous, and is more prone to cracking. 

Figure 1.7: Concrete mixing process, just before adding water and stirring the mixture.

Concrete Casting

When casting the silicone mold with concrete, it’s important to pour slowly. This helps to limit the number of air bubbles that are trapped within the mold. To aid in the evacuation of trapped air, I once again agitated the silicone mold by vibrating it. This brought the vast majority of air bubbles to the surface, although there were still some trapped lingering bubbles. These air pockets ended up giving a unique surface finish on the final parts and became something I liked.    

Figure 1.8: Carefully filling the silicone mold with the concrete mixture.

Post Processing

Once the concrete had dried completely I removed the parts from the silicone mold. The next step was to sand down the small amount of “flash” on the bottom surface of the parts. This is caused by the silicone mold not being filled all the way with concrete. When this happens the concrete experiences capillary action, which causes the concrete to stick and rise on the perimeters of the mold. Additionally, I sanded a few regions on the hollow planter parts to ensure they would have a slip fit with other components when stacked.   

Figure 1.9: Sanding concrete hollow planter with 220 grit sandpaper block.

Decorating

With our post-processed components completed, it's time for the fun part. I started by laying out an arrangement that I liked. From there I decided which areas would have plants and soil, and the areas which would only have rocks and moss. The stack-ups of the hollow planters were filled with soil, to help provide nutrients for the succulents I planted within them. As a finishing touch, I added some small rocks around the succulents and filled a few other areas with rocks and moss. I opted for a succulent and moss-themed design, but there are many other styles one could choose. For example, a desert-themed planter with cactus and sand.  

Figure 2.0: Adding small river rocks to cover the soil surrounding the succulents.

Finished Product

Alternate Applications

The process of turning 3D printed parts into a silicone mold and then using it to cast in another material could be applied to a wide range of projects. Although the complexity of these 3D printed parts is somewhat limited, there are design choices that can be made to overcome these limitations. Additionally, the material you choose to cast with can vary as well, for example, you could replicate this project but use chocolate instead of concrete. The possibilities are nearly endless. If you’re interested in trying out this manufacturing process but aren’t sure where to start, here are some project ideas to get you started:  

• Concrete Vases
• Desk Organizers
• Concrete Coasters
• Candle Holders
• Phone Stands
• Business Card Holder
  

Conclusion

At first glance, it probably seemed like a daunting task to produce a consumer-quality concrete component from a few 3D printed parts and some silicone. But once the manufacturing process is broken down into its fundamental steps, it becomes a much easier project to comprehend. Hopefully, as you’ve progressed through this article you’ve developed a better understanding of how to turn 3D printed parts into concrete masterpieces and found some inspiration for your own DIY projects along the way.

Now go out there and Make Something Wonderful！