How to Design Enclosures and Molds using a 3D Printer and the FormBox with Agustín Arroyo
Today we're handing over the keys to the Mayku blog to Digital Fabrication Expert, Professor at UFV Madrid and WikiFactory Content Developer, Agustín Arroyo. In this article you will learn the basics of designing for vacuum forming and how to adapt 3D printed designs that you already have access to for the Mayku FormBox.
The Mayku FormBox is an excellent companion to a 3D printer to allow you create flexibility of materials, whilst also saving you time and money when it comes to duplicating 3D objects. Over to Agustín for a lesson in adapting 3D printed parts for vacuum forming.
If you'd like to learn the basics of mold design first, read Agustín previous article before you move to the next steps of project planning.
Using 3D printing for prototyping and design
3D printing is one of the most common tools in a product designer’s workshop. During the last decade, it has positioned itself as a solid option when prototyping and even creating final products. But, why is that? Mostly because of how easily it can be combined with other technologies, including vacuum forming.
In this article, I’ll show you how you can use a 3D printer to make enclosures and parts of an electronics product that will be later manufactured with the Mayku FormBox.
Choosing a 3D printed project for the FormBox
Lazer Chazer is a collaborative and open-source laser toy for bored indoor cats. This easy to assemble DIY device allows you to choose or program custom laser movements that will entertain your cat.
If you check the project, you will notice that all the components that are not related to the electronics are 3D printed. Using 3D printed parts makes it highly customizable. However, it takes many hours to manufacture the enclosure, and the available materials aren’t the most suitable ones.
The device generates a laser beam which goes through a small window in the front, but it’s quite small. The idea is to make a transparent version that doesn’t require that window. Also, as the enclosure is transparent, the device can be used as an educational resource showing how it works and its different components without disassembling it.
Before you go ahead and select your vacuum forming project, you can read my guide to the basics on designing for this method; How to Design for Molds and Vacuum Forming.
From 3D Printing to Vacuum Forming with the FormBox
Lazer Chazer has three main components: the case, the front cover and the component trays. Let me show you how I duplicated the enclosure using some 3D printing and the FormBox.
Note: Please take into account that the following process requires prototyping and testing. Each component needs to be redesigned and transformed into a detailed template in order to create high quality vacuum formed copies.
The enclosure is the biggest part of the product. It doesn’t just have a large surface, but it’s also relatively tall. As it’s mentioned above, all templates should ideally be wider than taller.
Getting this part right took some time as the case holds all the other components together. The easiest method to get it right consists of working first on the enclosure design and then moving to the smaller details.
In the image below you can see the original enclosure design.
First I had to decide in which position the new template would be 3D printed and how it would be positioned during the vacuum forming process. I designed it in a way so that the Lazer Chazer logo, which is on the back, would be the first layer of the 3D printed part, which has a smooth surface. This way, the template would be turned upside down when creating the vacuum formed part, generating a nice and detailed logo.
The original design didn’t have any undercuts, but the walls had 90º angles, which aren’t recommended. Draft angles were added to reduce webbing and increase part quality. I tried to keep the design as similar to the original as possible, but vacuum forming requires a different design style due to manufacturing limitations.
While the 3D printed version had many side rails to insert the component trays, the vacuum forming template has just one at the bottom. The two reasons why this change was made were:
- The vacuum formed case isn’t as rigid as the 3D printed version, and the component trays wouldn’t be held in place in a safe way.
- The component trays also had to be redesigned, being necessary just one side rail.
As you can see in the image below, the side rail of the vacuum forming template is much bigger than the ones on the 3D printed version. This change was made to make sure the component trays, which can bend, didn’t move once the device was closed.
The Lazer Chazer needs to be connected to an external battery to work. That is done through a hole in the back which exposes the Mini USB port of the electronics. As holes need to be manually cut in vacuum formed parts, a 1mm deep rectangle was added. That rectangle would be used as a cutting guide during post processing.
All vacuum formed parts need to be cut from the plastic sheet, and I added some small details to make this process easier. For example, two small lines were added on the top and bottom sides of the case as the front cover will slide through them. However, the biggest detail is in the front of the case, as it was extruded 5mm so similar guides could be added on the sides.
Adding these guides allow me to make perfect cuts without using additional equipment. It’s simple and functional.
Once the design was ready, I rounded the corners to reduce webbing and help with part releasing.
The front cover redesign was quite straightforward compared to the case. That was mostly because it had to be as simple as possible.
In the image below you can see how the original 3D printing version looks like. It is made with an opaque material with the Lazer Chazer logo and the laser can only go through a small window in the top part. Also, multiple pins on the back hold the front cover connecting to the side rails.
The redesigned front cover template is basically an extruded rectangle. The front window was removed since the vacuum formed part will be made with a transparent plastic sheet. The logo was also removed to have a clearer view of the components, which are in the bottom half of the case.
The way the front cover is held in place was also redesigned considering the thickness of the material and how flexible it is. Two small connectors were added to the sides corresponding to the top and bottom of the Lazer Chazer. These two connectors are inserted in the small cuts that were added to the case to hold the front cover leaving a clear front view.
As I did with the case template, surface details were added so that the cutting process could be done without measuring tools.
The electronic components are divided into two trays: one with the protoboard and the electronics, and the other one with the servo motors and laser module.
While the case and front cover parts also considered aesthetics, the component trays are purely functional. This allows for more design optimization, increasing rigidity and reducing the post processing time.
The protoboard tray was easily redesigned. As this tray touches the bottom part of the case, it wasn’t necessary to increase rigidity. Also, the 3D printing version was quite simple, which made the redesign process quite straightforward.
The things that needed to be considered when redesigning the protoboard tray were the following:
- The tolerances between the mold and the protoboard. The protoboard should perfectly fit.
- The Mini USB port from the electronics (which is on top of the protoboard) should be at the same height as the hole in the back of the case.
- The outer design of the tray needed to be modified as the shape of the case where it would fit was different due to the draft angles.
Once the protoboard tray was ready, I moved to the servo motor tray. This part was a little bit trickier as the current design didn’t work with the new case. The 3D printing version was flat and it was held in place thanks to a side rail which were at a specific height.
The part had to be completely redesigned. This tray needed to sit at the bottom of the case as it wouldn’t hold to the sides due to the material’s low rigidity. However, the servo motor height needed to be the same. For this reason, the new vacuum forming template has a pyramid shape with the servo motor socket on the top.
The holes on the side of the 3D printed version are necessary as the servo and laser module cables need to be connected to the electronics. On the vacuum forming template the holes were transformed into surface details so they are easily cut during post processing.
Now that all the parts have been redesigned, it’s time to 3D print the templates.
What are the ideal 3D Printer settings for vacuum forming masters?
Before 3D printing the templates you need to consider the following slicing aspects.
Layers generate a particular texture on the side of the 3D printed part. As it has been mentioned, the FormBox is great at picking up those textures. Even though there are different ways to obtain a smooth surface finish, such as sandblasting or sanding, controlling the layer height is the easiest solution.
It’s recommended to use a 0.15mm layer height or even thinner. In the image below you can clearly see the result when vacuum forming a part that was 3D printed using a 0.25mm layer height. Consider that the image corresponds to a vertical wall, which are the ones that usually offer the best surface finish.
If you’re prototyping functional parts, don’t worry about layer height. You can use layer heights of up to 0.3mm to prototype faster and then move to thinner layers once you’ve got the final design.
Wall Thickness and Infill
The templates you 3D print must be resistant. When the hot plastic sheet forms the three-dimensional shape it heats and applies pressure to the template.
See what happened to an early prototype that had thin walls and low infill percentage. The hot plastic sheet heated the template and it deformed on the top part generating the pillowing effect (caused by the inner infill).
The template should be as rigid as possible as the pressure and heat can deform the template while the mold is being formed. It’s recommended to use a 2mm wall thickness and at least 25% infill. However, if you’re using a large template, you will need to increase the wall thickness as the pressure applied to the template’s surface will be higher. We recommend testing different infill and wall thickness settings to find the perfect balance between print time and resistance.
In the image below you can see the sliced preview of the Lazer Chazer case template. It has thick walls and a high infill percentage to make sure its shape doesn’t deform when used.
Minimum Feature Size
Even though the Formbox captures surface details very well, it does it better on the top part of the template than on the sides. You don’t need to worry about making the details too big as the mold will capture even the top surface texture, but it’s recommended to make some tests before jumping to the final template.
If you’re going to engrave text on your template, you should focus on the engraving depth rather than on the shape. For example, a rough Lazer Chazer logo test was made to make sure the size and shapes created clean text on the mold.
When using a 3D printed part as template with the FormBox, there are four different surface finishes you will find:
- Clear: You will get this surface finish when using the bottom part of your 3D printed model. If your 3D printer has a smooth print bed such as glass or PEI sheet, the mold will have a clear finish.
- Side lines: This is what happens when you create molds of three-dimensional parts. The sides of the 3D printed object show the unique layer line texture.
- Top surface lines: If you use the top part of your 3D printed object to create the mold, you will get a smooth surface but you may be able to see some small lines depending on how well calibrated the 3D printer was. These lines are normally not visible when making objects using the mold.
- Frosted: If you used a composite material that has wood or other particles that leave a rough surface, that will generate a frosted finish on the mold.
It’s always recommended to use heat-resistant materials to 3D print your templates. As a rule of thumb, ABS is more heat-resistant than PETG, and in third place we have PLA.
However, if you only have PLA or if you don’t feel comfortable using new materials, you can always increase the template’s resistance by increasing wall thickness and infill. For example, you may be able to make a high quality template using 150g of PLA (high infill) or 120g of ABS.
In any case, testing different template densities and materials is the best way to find out the right settings. For example, I learned that 10% infill was not enough for a PLA part after testing one of the front cover designs.
Preparing 3D Printed Parts for Vacuum Forming
Now that we’ve designed and 3D printed the different templates to make a vacuum formed version of the Lazer Chazer, we can see how different the original model and the templates look. While the 3D printed version of the device looks like a real product, the templates look like industrial equipment.
Now it’s time to turn on the FormBox and prepare some plastic sheets. I’m going to use transparent sheets as I want to use this device as an educational resource, showing its components to my students and keeping them safe from my cat’s claws.
As I want to try different template designs with small changes, I’ve arranged some of them together so I can make several parts with just one plastic sheet. I can make four molds with one plastic sheet as I’m using thin and wide templates.
Now that all the parts have been made it’s time to cut them and clean the edges so they fit smoothly.
Finally, I’m going to assemble all the components and make sure that the Lazer Chazer is ready.
Advantages of vacuum forming with the FormBox
Increase production speed
Adapting a 3D printed design so that it can be made with a vacuum forming machine means that you can speed up production without having a print farm.
Let’s take the Lazer Chazer case as an example. The original 3D printed version takes 6 hours and 8 minutes to print with average settings: 0.2mm layer height, 0.8mm wall thickness and 10% infill. On the other hand, the vacuum formed version can be made in 5 minutes. These 5 minutes include placing the template, heating the sheet, the vacuum forming process and part releasing. To be fair, the template 3D printing process should also be considered, which adds 7 hours and 13 minutes.
Now that you know how long it takes to make a Lazer Chazer case, imagine that you need to make 10 cases and you only have one 3D printer. As you see on the image below, vacuum forming is 661% faster than 3D printing.
In both cases, post processing and file preparing time was ignored. I found that both 3D printing and vacuum forming don’t usually require a lot of postprocessing and the previous preparation - mostly heating and preparing the material - takes the same amount of time.
Concerning production speed, if you want to make just one unit, both 3D printing and vacuum forming take almost the same time. However, if you make two or more units vacuum forming is the way to go.
Decrease cost of materials
If production speed wasn’t enough, vacuum forming also offers some advantages in terms of material cost.
Let’s use the same Lazer Chazer case example. A spool of good quality PLA plastic costs 25€ and it weights 1Kg. The 3D printed case weighs 87g and it costs approximately 2,17€. On the other hand, the Mayku Form sheet 30 pack costs 39,99€, which makes it 1,33€ per sheet. One sheet is used to make every case.
Again, if you needed to make 10 cases, you would notice that vacuum forming is 23% cheaper than 3D printing. And that includes the 3D printed template, which weighs 140g and has a cost of 3,50€.
You should also consider additional costs such as electricity consumption, additional equipment and the operator’s salary, which are closely related to production speed and ease of use of the equipment.
Choose from new materials
In the end, vacuum forming isn’t just about making products in the most efficient way. It’s about the unique products you can make with a vacuum forming machine.
FDM 3D printing offers a wide range of materials with different mechanical properties and surface finishes. However, vacuum forming can produce transparent and lightweight parts, which are things that can be hard to achieve with FDM 3D printers. You can also use your FormBox to make molds, which you can then cast into a variety of other materials.
Vacuum forming and 3D printing compliment each other. None of these technologies can make everything you need, but combined, they give you the chance to unleash your creative potential.
Some of the main advantages of combining the Mayku FormBox with FDM 3D printers include:
- Increased production speed: Make more in less time.
- Material cost reduction: Use vacuum forming to make critical components at a lower cost.
- New surface finishes and material properties can be achieved using the Mayku Formbox.
Combine both technologies and start making incredible products! If you give this project a go, be sure to let myself and @TeamMayku know.
Want to know more about the Mayku FormBox? Request to speak to a specialist today and a local expert will contact you to discuss how the FormBox could transform your workflow. For more inspiration and ideas, follow @TeamMayku on Twitter, Facebook, Instagram and YouTube. Learn more about Agustin's work on his website.
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