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December EDU Project: Hot Tub + Hour Of Code


December EDU Project: Hot Tub + Hour Of Code

As the chilly winter weather sets in across the nation, we thought this would be a welcome subject for this month's Thornburg EDU Project. At the end of this month's EDU Project, we've got a challenge in conjunction with the #hourofcode initiative, so be sure to check that out as well! Now, on to Dr. Thornburg's lesson!


Hot tubs are relaxing! They come in a wide variety of models, but the main concepts are the same. Unlike swimming pools, hot tub users generally just sit and relax in warm water with small jets blowing bubbles and water streams on your back. After a half-hour, you emerge from the tub well relaxed with aches in your joints pretty well dissipated. The therapeutic value of hot tubs is why they are in training rooms for athletic teams, but a lot of people have installed hot tubs in their homes.

Hot Tub Image Source: Morguefile

Hot Tub Image Source: Morguefile

This project involves the design and building of a hot tub suitable for inclusion in a doll house. This project involves a lot of mathematics, and even explores the concept of water pressure. While it doesn't have any jets in it, you can add those if you want, and make a nice place for your fingers to relax, since our model is pretty small. Normally, hot tubs are about 2.5 meters across. Ours has an outside dimension of only 13 cm.

As with the other projects we've explored so far, this one will be done using Tinkercad.

Step-By-Step Design

1. The first step is to put the ruler on the workplane, and drag a Polygon from the Basic Shapes area of the screen onto the workplane. The shape of this polygonal prism is hexagonal ― just what we want.

2. Our next step is to resize this shape to represent the interior of the tub. The original dimension is 20 mm corner to corner, and 17.32 mm across the faces. The goal is to maintain the aspect ratio and resize the hexagon to 120 mm corner to corner. The face to face size will be 120 x 17.32 ÷ 20 which is 103.92 mm. Next, set the height to 40 mm.

3. Next, we'll make the outer part of the tub. Select the hexagonal prism, copy it, and paste it. To keep from being confused later, make the new shape a different color.

4. Move the interior piece up by 5 mm. You can pull it up with the black arrow, or enter 5 mm in the base position field on the left of the screen, just below the height setting.

5. Now it is time to change the size of the outer piece. Select it, make the corner to corner dimension 130 mm, and adjust the face to face dimension proportionately. In this case, the size will be 130 x 103.92 ÷ 120 which is 112.58 mm.

6. Now we need to align the two pieces so they are centered. Select both pieces, choose the align tool and click on the center button for both the X- and Y-axes. This might be easier for you to see if you use the Top view of the workplace.

7. When you are done, the pieces are centered like this.

8. Next, select the interior piece and choose the Hole tool to the right of the workplace.

9. Select both pieces, and click on the Group button to the top right of the workplace. This gives us the finished view of the tub itself.

10. Now we need to add seats to the tub. Drag a cylinder to the interior of the tub.

11. Change the seat size to 30 mm in diameter, with a 20 mm height. Finally, raise the seat 4 mm from the base. As before, this kind of movement can be done with the black arrow, or by entering 4 mm into the field below the height field.

12. Now move the seat to one of the corners so it makes a tight fit.

13. Copy the seat, and paste five more of them to the interior of the tub. Position them to the remaining corners, and you're done.

14. If you choose the Home view of the workplane, you can see a nice view of the tub. Export everything to an STL file and you're ready to print!

Printing & Assembly

Print a copy of your tub and check to make sure there are no holes in your model from which water can leak.

Things To Do & Notice

Calculate the volume of your tub. Here are some hints: A hexagon is made from six equilateral triangles. In our case, these triangles are 65 mm on each side. The tub is 35 mm deep, and you need to subtract the volume of the six cylindrical seats, each of which has a diameter of 30 mm and a height on 19 mm.
Using a measuring cup, fill your tub with water and compare the volume you found with the volume you calculated. If the numbers are different, how do you account for this?
Our tub has a wall thickness of 5 mm. Water exerts pressure on the walls of its container. Since the density of water is one gram per cm3, what is the pressure inside a full tub in newtons (N) per cm2? Where is this pressure the highest? Where is it the lowest. How thin do you think you can make the tub walls and still safely hold a tub full of water?

#HourOfCode Challenge

From December 5th to the 11th, multiple companies, schools, and organizations are participating in the Hour Of Code program to encourage students to learn and experiment with code. We'd like to get in on the action with this monthly lesson. Can you reconstruct this month's EDU lesson using the code based CAD program, BlocksCAD? If you send us a screenshot of your code solution with an image of your final model, and we will put your name in the hopper to win a 1kg roll of PLA filament in the color of your choosing! We will select a winner from the submissions on January 1st, so you have nearly a whole month to fit in an hour of code! Best of luck everyone!


3D Printing in the Classroom — Who Cares?


3D Printing in the Classroom — Who Cares?

We're excited to bring you this blog post by our Director of Education, David D. Thornburg, PhD.

I've chatted with lots of teachers over the years and now that 3D printers are becoming commonplace in many classrooms, a major complaint has emerged: “We got a printer for our class and after the kids made key chains, we didn't know what to do next, so we don't use it anymore."

This challenge is so commonplace that I thought I should address it. My view is that any technological tool used in education needs to be evaluated on the basis of its curricular connection. Just because something is new and flashy doesn't mean that it should be brought into classrooms. This applies to computers, tablets and other devices, including 3D printers.

In the realm of 3D printing (for example, in the STEAM fields), there are five tasks that form a sequence. These include background on the curricular topic, the design of the 3D parts for the project, the printing of the parts, their assembly into a finished artifact, and experimentation with the object to develop a deeper understanding of the topic. I show this as a loop because the cycle can repeat with embellishments for interesting projects.

Every one of these topics is important. Contrast this approach with one that involves simply downloading and printing designs stored on sites like Thingiverse. While such sites are useful for providing models of difficult-to-design parts, they pale in comparison with the learning that happens when students design projects on their own.

To illustrate the process, I'll show part of our STEAMtrax high school curriculum project on water turbines.


Hydroelectric power provides a significant percentage of the electricity used in the US. The topic of water turbines bridges physics, engineering and mathematics. It allows students to explore Newton's laws, electric power generation and other curricular topics.


After learning about the kinds of turbines used in hydroelectric dams, students are ready to design their own turbine for testing. While there are lots of design tools available (many of which are free), this project uses a free authoring environment called BlocksCAD. BlocksCAD has the advantage of being easy to learn, and for supporting the design of complex shapes.



Once the design of the various parts is completed, the finished designs need to be printed. In our case this includes the turbine wheel itself, the wheel holder, and the end caps placed on the wheel axle that also allow a small DC motor to be added as a generator.


The next step in the process is the assembly of the final system, including its connection to a voltmeter to show how much electricity is produced then the turbine wheel rotates.


Once the assembly is completed, the wheel is subjected to a stream of water and students can see how much electricity is produced by a water turbine they built themselves. This leads to some new questions. For example, our first wheel had eight blades. What would happen if we had six blades ― or ten?

Because our modeling language is parametric, changing blade designs is as easy as changing the value of one variable. This lets students print and try differenct wheel designs with ease. By using an inexpensive laser tachometer, wheel rotational speed can be measured with different water flow rates and comparisons can be made between wheels with different numbers of blades. Suddenly this activity has a strong math component that aligns nicely with existing standards.

From this point, you can go back to the Background step and launch an exploration of different kinds of turbine designs.

When viewed from this perspective, 3D printing is a powerful tool in education. Instead of presenting the curriculum in a linear lecture-driven format where it is quickly forgotten, students learn through the process of “constructionism” where the things they learn will stay with them a long time.

The approach I just described applies to the curricular materials we develop at Polar3D under the STEAMtrax name.

By all means, make a nice keychain if you want, but then please quickly move to curricular-based projects like those provided by STEAMtrax to transform the learning experience using 3D printers as the key technology to do things you simply couldn't do before.


Thanksgiving Challenge Winners!


Thanksgiving Challenge Winners!

Now announcing our Thanksgiving Challenge Winners! We're so thankful for the bounty of 25 entrants, and the decision was a tough one. After much deliberation we focused on a few distinct qualities to chose the winners: theme, build difficulty and detail. Without further adieu, here's our runners up!

Second Runner Up - "Thanksgiving Utensil Holder" by: Brayden Boyum

"The turkey is a decoration and the two little hills on both sides you use to set your forks and spoons and stuff down on it."

First Runner Up - "Thanksgiving Table" by: Jada Fox

"The best day of the year where family comes together this little table shows a beautiful dinner with many different food and the word family on the side because family is the best thing to have at a Thanksgiving dinner."

Winner - "Cornucopia" by: Jayna Searles

"An iconic symbol of the first Thanksgiving, this cornucopia will make a great decoration for your Thanksgiving table."

Congratulations to Jayna on her design challenge win! She will be receiving a roll of our cool Wood Filament! The runner's up will receive a roll of filament in the color of their choice too. Don't forget, you can download these great designs (using the links above) or any of the other great challenge entrants here on the Polar Cloud. Thank you to everyone who participated and keep an eye out for our upcoming Christmas Challenge, debuting soon!


October EDU Project: Building With BlocksCAD


October EDU Project: Building With BlocksCAD

This is another installment in the monthly, continuing series of Educational Projects by David Thornburg. This October lesson, aimed at middle school students or higher, focuses on an interesting design tool called BlocksCAD. Without further adieu, here's David Thornburg with his monthly lesson!

Introducing BlocksCAD

One of my favorite new 3D design tools is a programming language that design shapes and generates a STL files as its output. This language is called BlocksCAD and it is made by the good folks at Einstein's Workshop ( BlocksCAD is and easy-to-use version of OpenSCAD, a tremendously powerful design tool that can be tricky for younger users to master. If you are familiar with programming languages for kids like Scratch (, you already know about coding through the assembly of jigsaw-like pieces to create a program of your own design. BlocksCAD works in a similar way, making it perfect for beginners without limiting the complexity of objects you can design. BlocksCAD works in the cloud, making it perfect for iPads and Chromebooks. To show you how it works, let's design a card holder. While this is not an educational project per se, it showcases the elements of the language. Since “coding” is increasingly of interest in education, it makes sense to highlight the language in this blog.

Go to the BlocksCAD site ( and log in. You will see the screen divided into three areas: a set of colored bars on the left denoting various shapes and operations (the commands of the BlocksCAD language), a window in the center where you will have your program, and a window on the right side where you can see your model as it is progressing. This is also the window you'll use to export your project as an STL file for printing.

Next, in the area to the right of Project Name near the top left of the window, type Card Holder, and click on the 3D shapes button to the left of the screen. This gives you a few options. Click on the Cube icon at it will show up on your center screen.

Enter X, Y and Z values of 60, 95, and 3 mm and choose “centered” for the shape. Press the Render button to see the result.

I like to choose “centered” whenever I can so I know the origin of every object. Objects can be moved and rotated using the transformation tools by pressing the Transforms button on the left side of the screen.

BlocksCAD supports text, so we'll illustrate that next. Click the Text button on the left side of the screen and choose 3D text. This puts an operator on the screen in which you can add your text (I wrote “Genius”), the height of the text in mm, the font (I chose Liberation Serif), and the amount by which the text is extruded (3 mm is fine for us). The only thing that's missing is the “centered” option, which bums me out. The great folks behind BlocksCAD are working on this. But, no problem for us, we have two cool tools in the Transforms button to fix this ― Translate and Rotate. I also used Union from the Set Ops button to combine everything using the Union block. This is important because we will soon rotate the whole plate, and want the cube and the text to stay together.

As you can see, we rotated the text 90º around the Z-axis and translated the text so it is somewhat centered horizontally and located near the top of the cube.

A quick note regarding text: BlocksCAD only provides a few typefaces because they can't go onto your computer and prowl around for your own fonts. Computer-resident software like OpenSCAD doesn't have this restriction. I mention this because it might come up in one of your later projects.

Our next step is to rotate our shape by 60º around the Y-axis so it forms a tilted back for our business card holder.

Once this is done, we make another “cube” with the same dimensions as the first, rotate it 60º the other way (quick, what positive rotation angle is equivalent to rotation by -60º?  (No fair looking at the numbers below!)

After doing the rotation, you need to translate the location of the card holder back so it interlocks with the front. You can either use your vast understanding of trigonometry, or tinker around until you get it!  I'll let you decide which approach is fastest.

I've chosen to put each of the pieces together with another Union block. The first item is our rotated part with the text. Next, we added the back, and if you click the + sign on the Union block you'll add a place for another part to add.

Now we need a base to hold the stack of cards. To do this, add a cube with X, Y, and X dimensions of 10, 95, and 3 mm. This gives us a flat base you can add to the holder with a Translate command. Add this part to the Union block.

Finally, you need to add a lip to make sure the cards don't slip out the front. This is made with another translated “cube” with X, Y, and Z dimensions of 3, 95 and 10 mm that has been translated into place and added to the Union block. 

That's it!

Now when you render the shape you'll get the finished card holder ready to save as an STL file and send to your printer. If you print the card holder the way it will sit on a desk, your printer will add supports to the interior of the holder that you take off when the print is finished. Now, if you want, you can rotate the entire model by 90º so it prints sideways. This way, no supports are needed, and the finish of the card holder might be prettier. You should try both ways and see which one you like best.

The finished card holder is shown below. The goal of this blog was to show a few of the nice tools in BlocksCAD. You should continue to experiment on your own and let me know how you like the language.





Haunted Halloween Challenge Tutorial


Haunted Halloween Challenge Tutorial

A 3D Printed Jack O Lantern with an LED candle inside lights up the whole print!

A 3D Printed Jack O Lantern with an LED candle inside lights up the whole print!

We've just launched the Haunted Halloween Challenge! This challenge is a little different than previous ones — we'd like you to make a design that should be lit up from the inside! It seemed like a great opportunity to help out our students and teachers with a little tutorial.

Due to the fact that excessive heat and finished 3D Prints don't mix too well, we suggest that you use a flameless LED candle to make your prints light up. As evidenced by the adjacent photo, it works really well! You can find inexpensive, flameless LED candles at most major stores, especially during this Halloween season.

To make a hole big enough for a flameless candle in your model, first you'll need to measure the candle you'd like to insert. Our candle, for the sake of the tutorial, was roughly 1.5" (38mm) in diameter and 1.5" (38mm) tall. To ensure enough room inside the print, we decided that making a slightly larger cylinder of 1.75"D (44mm) x 1.75"H (44mm) would work best. We suggest that you also make the hole slightly bigger than your candle to be safe. 

Now you'll need to create the spooky model you'd like to illuminate. That part is entirely up to you and we look forward to seeing your design! For our tutorial, we've started with a basic, not-so-scary pumpkin in the center of the workplane. We first raised the pumpkin to make some space beneath it. Next, we created the cylinder and scaled it to the proper size using the control handles on the model.

With the cylinder finished, we lowered our pumpkin model on top of the cylinder so that they overlapped. To ensure that the hole works in printing, we extended the base of the cylinder past the workplane using the control handles. Then with the cylinder selected, we changed it from "Color" to "Hole" and grouped the pumpkin and cylinder hole together. This creates a pumpkin with the proper candle hole inside! 

Once you've crossed this point with your design, you can save it in TinkerCAD and download the STL file for printing. When you upload your design to the Polar Cloud for printing, we suggest you use a small "Infill Amount" in your Cura settings (5-10%). This will allow more light to shine through from your candle! Finally, be sure you have support material turned on to ensure your candle hole doesn't cause your part to collapse during printing. With those settings in place, you can press print and watch it go!

Once your design has printed, simply remove the support material and insert your LED candle! Take a picture of your design all lit up and send it to us, and we'll be happy to share your spooky creations. Best of luck to everyone in this challenge and have fun printing!