Introduction

Visualizing the human anatomy can be hard to do effectively through textbooks, lectures, and pictures alone. Additionally, people who are hands-on learners may not retain information as well without a physical demonstration. A great way to overcome these challenges is through physical anatomical models of the human anatomy!

Making a detailed 3-dimensional heart that actually looks like a real heart can be difficult to manufacture. One simple way to accomplish this is by using FDM 3D printing! With this method, the product can be visualized in 3 dimensions before it is physically created through CAD software. Additionally, in the slicer software, the product’s size, infill density, layer height, and orientation can all have an effect on the cost and quality of the final product that can be optimized for your desired results.

Printer Preparation

In the industry, CAD software is used to model a desired object that the user wants to print. For this project, we did not do any CAD, but we found a great model of a heart from ThingiVerse (https://www.thingiverse.com/thing:4601991). After downloading the file for the heart model, it was imported into a Bamboo Slicer.

For this project, we wanted to show the reproducibility of the print by making two identical products. In the slicer software, we were able to fit two of the hearts onto one plate so that they could both be printed at the same time. The heart model came in two pieces each, making four bodies on the print board for the two hearts:

When orienting these hearts on the print bed, the orientation and features must be looked over to ensure a good print is possible. For both pieces, the flat smooth face is faced down towards the printing bed so that the model has a good base and makes good adhesion to the print bed. With this face down, we can analyze the features. The small piece has no overhangs or anything difficult to print, so those were left alone. For the larger half, there were some obvious overhangs that could cause some difficulty or errors in the print. For this, an automatic support feature on the bamboo slicer software was used to make supports for these halves (shown in green):

For this print, we used PLA as our material. When using FDM printing, the detail of the print is an important factor to consider when making a good and efficient print. The layer height is a huge factor in the precision of details on FDM printers. Because the heart has small details in the veins, crevices, and has a lot of round shapes, a small layer height was important to maintain the small details. For this print, we set the layer height to 0.1mm.

The bead of Bondo was cut flat against the print using the exacto knife shown in the image above. Once this bead was cut, the edge was still not perfectly smooth, so air-dry clay was used to fill in the final small imperfections:

Once dried overnight, the clay was sanded to make a perfectly smooth transition between the two halves. Additionally, the part as a whole was sanded to remove any burrs from the supports and any spots where the layers were obvious and not as smooth.

This process began with a high-grit sandpaper (around 80) and was gradually increased to higher grits (up to 200) to make a smoother finish:

Now the two hearts are ready to be painted! The first step to paint these hearts is to use a primer to ensure good adhesion of the paint to the PLA. This was done using automotive filler primer. This filler primer builds up a thick coat of primer that is able to be sanded once dried. This was beneficial for our final product because it will help further conceal the gap between the two halves and any layering evidence that may have been missed or hard to reach with sanding:

With the primer on, dry, and sanded, the hearts were now ready for some color! To match some existing sets of 3D printed organs, we used an acrylic paint set. First, the heart was painted in different shades of red to resemble a real human heart.:

For the final product, the veins were colored black for better visibility: