For us, we simply attach a thin Teflon film to protect the silicone from contacting the resin directly so as to extend the lifetime of resin container. You might think that Teflon is a non-stick material. In general, it is true, but some cured resin materials can stick on the Teflon film firmly and are very hard to separate. The followings are the reasons why a cured layer could be hard to separate.

1. Some cured resin has a strong Van Der Waals’ force with Teflon. When the cured area is large, the separation force is high.
2. Over-cured resins tend to have a much higher adhesion to Teflon.
3. Hollowed model without vent holes could introduce tremendous suction force.
   
4. Bulk shrinkage in a tapered solid region could turn a flat layer into a bowl like shape that could also introduce tremendous suction force. A thin cone shape is more likely to happen. This phenomenon often happens when:
   • a. Material itself has a high native shrinkage
   • b. Fast curing ( < 1 second) due to strong light intensity or more photoinitiator concentration could introduce higher shrinkage for the same material
   • c. For a fast resin, low separation speed introduce more on-going curing after the light is turned off. Low separation height does not mix the resin near the curing area with fresh resin outside the curing area well enough so the viscosity becomes higher in the curing area gradually. The combination of the above two could introduce differential shrinkage between layers and across the layer and form a strong suction effect. The situation is more severe when printing repeated patterns. This suction force may result in a phenomenon where the cured layer suddenly sticks to the Teflon and does not come apart (as shown in the photo). To provide an example, suppose a certain resin has a normal exposure time of 1 second. During the printing process, the resin has absorbed photons from both background and scattering exposure near the exposed area. Please note that the resin in the build area close to the vat floor tends to have higher viscosity when partially cured and tends to stay near where it is. If the accumulated absorbed dosage is equivalent to 0.5s of normal exposure, the next print layer will technically be over cured for 1.5 seconds (1 second for the exposure time + 0.5 second from already being cured due to background and scattering exposure). During the buildup of the partially cured resin, the effective over-curing will keep increasing the adhesion between the cured layer and the Teflon film. If you cannot use another slow resin instead, you would need to increase the lifting speed and lifting height to slow down the buildup.
     

How will the above affect your print? They will significantly affect the consistency of the separation force and increase the failure rate. Even if the print survives, the surface quality may be deteriorated. They will affect both the Teflon film lifetime (please refer to the PSP resin container blog ) and the printing quality.

Knowing the reasons as to why high adhesion occurs and the solution to it will greatly smooth out your printing process. Even if your print did not come out the way you expected, it is important to understand why it happened. This way, you know what the cause of the problem is and learn to avoid it next time. Learning from failed print is perhaps one of the best way to quickly learn and understand more about SLA printing!

What is a PSP Resin Container?

PSP stands for Passive Self-Peeling. This is the key component to the “secret” of Kudo3D’s high-resolution 3D printer. Instead of forcibly pulling the printed layers apart from the vat floor, the flexible PSP resin container greatly reduces the separation force between each layer by passively peeling it apart. There is no extra motor to pull the container away and the bending of the container mimics the action of peeling a piece of tape away from a hard surface. This greatly reduces the separation force and thus results in a faster speed as well as the ability to print large models and fine details compared to other types of layer separation mechanism. The vat floor is formed with a layer of elastic clear silicone to assist in peeling. It is well known that clear silicone tends to react with resins and become cloudy after one or two prints on the same spot. Depending on the resin used and number of layers in a model, silicone could permanently bond with the cured layer when reacting with the resins. Therefore, we cover the silicone with a thin layer of Teflon to protect the silicone. By doing so, the lifetime of the container is greatly extended.

Brief History of Kudo3D’s Different Generations of PSP Resin Container

First Generation to Third Generation Resin Container.

During Kudo3D’s Kickstarter campaign, back in May 2014, we released the first generation of PSP resin container along with the Titan 1. It was a fairly simple design: acrylic container with silicone and Teflon, along with 2 thin plastic side walls. These side walls were first held together with double sided tape and sealed with silicone. Though it fulfilled everything that it promised, there was a slight problem with this container. When the container is lifted too much, the silicone sealant may not work. The resin may get to the adhesive through the gap between the silicone and the side walls. The resin weakened the holding between the side walls and resulted in a leakage after using for a while. Although first generation container has such a problem, it was easy for DIYers to make it by themselves.

Upon learning this, our team quickly found a solution to this problem. Using a stronger chemical bonding to replace double sided tape, we released the second generation of PSP resin container. The interface between the side walls and the acrylic is strong to prevent the resin from seeping through. However, we soon found that 3D-Materials resin could react with the side wall materials and cut through the side walls gradually. The side walls lasted about 120 hours if the container was maintained properly. The 3D-Material resin users experienced a lower resin container lifetime that ultimately could led to leaking containers- if not caught early on.

To extend the lifetime, 3D-Material resin users needed to clean up the container after each use and must monitor the sidewall condition. When using non-3DM materials, the lifetime was much longer for the second generation PSP containers.

To be more compatible with 3DM resins, the PSP resin containers went through another round of testing and development in order to identify a material that resists 3DM resins while still be chemically bonded to the acrylic. Finally, Kudo3D’s R&D team was able to create the third generation of PSP resin container, our current generation, which is deemed “all-resin safe.” We are happy to state that we have been accident-free of leaking resin containers since the release of it over a year ago!

Soft Silicone? Hard Silicone?

Do you see the stickiness of the soft silicone?

But not for the hard silicone!

As you may notice, we offer two types of resin container: soft silicone resin containers and hard silicone resin containers. However, what exactly is the difference and how do you know when to use which type of silicone?

The soft silicone resin container, as the name states, uses a soft silicone with a Teflon sheet on top of the silicone. The adhesion force between the Teflon and silicone is much higher than of the hard silicone. The silicone is extremely sticky. If you touch the silicone (which we do not recommend unless necessary), the silicone will stick to your finger and stretch out, almost like when you try to pull gum off your shoe. This soft silicone resin container is very useful when printing smaller objects, such as rings or miniatures. The separation force, when using this resin container, is much lower and is generally recommended for first time users. The downside of this resin container is that the Teflon film is more susceptible to warpage and is not ideal for larger prints and prints require flat surfaces.

The hard silicone resin container uses a hard silicone and a Teflon film on top. The adhesion force between the Teflon and the silicone is much lower than of the soft silicone. If you were to touch the surface, the surface will feel tougher and will not come up along with the finger. Unlike the soft silicone resin container, the Teflon film on the hard silicone resin container will have less warpage, and users are able to print large objects or objects with a flat surface. The downside is that users will need to print at a lower printing speed, due to the higher separation force.

How Do You Maximize the PSP Resin Container Lifetime?

Although the silicone is protected by the Teflon to increase the lifetime of the container, the Teflon film itself still has a lifetime which is dependent on the separation force. Teflon film starts warping after experiencing a high separation force. Since Teflon and silicone are the two most chemically resistant materials, there is no way to permanently bond them together. Severe warpage could induce a gap between the Teflon film and silicone. The resin can enter through the gap and separate the Teflon from the silicone. If the silicone is not damaged, it is possible to replace the Teflon film. For hard silicone, you would need to use a clear double sided tape to bond a new film. For soft silicone, you would need to peel off the Teflon film　gently to avoid damaging the silicone, and lay a new film down slowly to prevent dusts or bubbles from getting in-between. For details, please refer to our forum.

To maximize the PSP　container lifetime, users must minimize the separation force and avoid model dropping. Please refer to Printing Guide to prevent model dropping. The shrinkage of the cured model could introduce warpage on the Teflon film. When the adhesion between the cured layer and the Teflon is larger, the front of the container will be lifted. If the container is lifted over 5 mm before dropping back down onto the frame, you may need to reorient the model and make some adjustment to the printing parameters. The height being lifted is a good indicator of the separation force.

There are many factors that has an impact on the separation force and thus the lifetime of a resin container:

1. Exposed area of a slice (reduce cross-sectional area)
2. Pattern of the layer (avoid circle and square patterns that are hard to separate)
3. Orientation of the print (avoid printing same pattern on the same spot)
4. Lifting speed (lower speed reduces separation force)
5. Exposure time (less exposure has less adhesion to the Teflon)
6. Reactivity of the resin (when the resin temperature is higher, the film is more likely to warp)
7. Native adhesion between cured resin and Teflon caused by the Van Der Waals’ force (use resins with less adhesion)
8. Layer thickness (thinner layer with less exposure has also less adhesion to the Teflon)

The golden rule to elongating the lifetime of your resin container is:

Once you understand how to minimize the separation force, it is quite possible to use a single PSP resin container for more than 100 prints. Take it slow and try to understand more about not only Kudo3D’s printer but also about its printing process involved. This will allow you to have a much more successful print.

Many of the consumer level printers were FDM (Fused Deposition Modeling) 3D printers. This involved a spool of filament to be heated to a high temperature and deposited into the shape that the user wishes to create via an extrusion head. With this type of printer, users only get the shape or form of the print but will not get details nor reach surface smoothness. In addition, the printing speed is relatively low.

Apart from the FDM technology, some 3D printers adopts the stereolithography (SLA) technology. Some SLA 3D printers use laser galvanometer to create patterns. This type of printer usually has laser stability and reliability problems.

How about the Titan 1 and Titan 2? Instead of the laser-based SLA technology, we use Kudo3D uses a highly reliable DLP technology developed by Texas Instrument to generate digital light patterns in a two dimensional fashion rather than scanning with a laser diode which is susceptible to ambient temperature, dusts and mechanical failure. DLP can also provide a resolution that laser galvanometer is impossible to match.

Using a better digital light pattern generator improves the resolution of the printers but it is not the main factor that attributes to our success in the last two years. So what exactly set our 3D printer apart from the other SLA 3D printers out in the market? The answer lies within the layer separation technology of the printer.

Most low cost SLA printers incorporate a bottom up light source and a transparent resin container. The challenge to these SLA printers is to separate the cured layer from the resin container floor. The separation force is proportional to the area of the cured layer. That is why most of the low cost SLA is not able to print big models.

To overcome this challenge, we have developed a patent pending passive self-peeling (PSP) technology that greatly reduces the separation force that others are hard to match by using both flexible and elastic materials for the resin container. PSP not only enables large area printing but also increases the speed and resolution of the prints. Since the peeling is passive, there are no motors involved. The printer’s structure is simplified. With less moving parts, the Titan 1 and Titan 2 are very reliable.

We understands that the lifetime of the consumables is a main concern for consumers while resin container is definitely a critical part for low cost SLA printers. Because of the low separation force, our container is less stressed and the lifetime is much longer. Besides, there is a protective film on the vat floor of Kudo3D’s containers to prevent the attack from the resin. As a result, our printers are compatible with more materials and relax the constraint for material developers.

With the PSP technology, Titan 1, our first generation printer, proved its worth when Kudo3D showed off a biomedical tissue scaffold research model printed at 37 micron XY resolution and 20 micron Z layer thickness. The beams have a diameter of 0.18mm (next to the print is a coffee bean for scale).

Pushing the printer to the extreme, we proved once more that our printers can print fine features that other low cost SLA printers cannot achieve. In the image below, a 45 micron thin needle was printed with the Titan 1. This needle is less than half the diameter of a hair. No other low cost printer can achieve this resolution.

Now in June 2016, we have launched its second-generation 3D printer, the Titan 2.

The new Titan 2 features:

• WiFi enabled.
  – There is no need to connect the printer to the computer after uploading the data.
• Allows web-based controlling.
  – Users can use any device (PC, Mac, smartphones, or tablet) to control the printer. Once the printing starts, the control device can be used for other purposes.
• One device can be used to command and control multiple Titan 2 3D printers.
  – This is especially helpful for those who would like to use the printer to setup a production line.
• Has a built-in computer.
  – The Titan 2 will be independent from the user’s computer.
• Has a shutter to reduce background exposure during prints.
  – This can ensure high quality prints.
  Additionally, the new Titan 2 will be assembled and calibrated before shipping, making the startup process even easier for first time users.

It is definite that 3D printer will keep evolving in technological advancement. Users are now able to print high quality things that they design or even better than they could ever imagined.

What makes the Titan 1 different from other SLA 3D printers?

But first, what is SLA 3D printing? SLA stands for stereolithography. In this method of additive manufacturing, a 3D printed object is built layer-by-layer using a liquid resin (photopolymer) that is cured using UV or visible light. What differentiates the Titan 1 from other SLA 3D printers, is that the Titan 1 uses Digital Light Processing (DLP) to shine light patterns via a projector. Many SLA 3D printers use a laser galvanometer to generate patterns.

Here’s a quick guide to everything you need to know about DLP and laser 3D printing.

DLP 3D Printing

A high resolution projector, light pattern powered by DLP technology, sits beneath the resin container and projects image slices to cure each layer. The projected image is just black and white as seen below. Since the resin is UV sensitive, the white areas of the projected image will direct UV and purple light to the areas require curing.

This method is quite simple when compared to the stunning resolution and details that it produces. The projector remains completely stationary during printing (and it is important that it doesn’t move or else the layers won’t align properly), which means there are few moving parts and little machine maintenance required. For Kudo3D’s Titan 1 and Titan 2, the only moving part is the stepper motor that lifts the build platform as the model grows after each layer is cured.

(Image Source: http://m.iopscience.iop.org/1758-5090/6/1/015003/article)

A sliced layer that will be projected onto the resin container. From Pranav Pancha’s model of the Eiffel Tower (https://grabcad.com/library/eiffel-tower).

Laser 3D Printing

Laser based SLA 3D printing uses a laser to trace out the cross-sections of the model. Similar to fused deposition modeling (FDM) 3D printing, where each layer is deposited in a continuous stream of filament, the laser essentially “draws” the layer to be cured. The laser is focused using a set of lenses and then reflected off of two motorized scanning mirrors (galvanometer). The scanning mirror directs the precise laser beam at the reservoir of UV sensitive resin to cure the layer. Alternatively, some laser based SLA 3D printers move the laser directly using a XY stepper motor arrangement similar to those used in filament based printer.
(Image Source: http://biega.com/3d-printing.shtml )

Now that we know how each method works, let’s do a comparison.

SPEED AND ACCURACY

DLP 3D printing is very fast because it projects the profile of an entire layer at one time, turning 2-dimensional images into a 3D object. In comparison, lasers have to trace out the entire sliced profile line by line which takes a lot more time. Small inaccuracies are also likely to occur and can affect the structural strength and surface smoothness of the print.

RESOLUTION AND BUILD SIZE

The projector makes DLP 3D printing versatile. Depending on the resolution and size of the 3D model desired, DLP can be easily moved up or down to adjust for your customized settings. DLP 3D printers can produce details with much higher resolution than laser based SLA 3D printers. However, resolution depends on the projected pixel size. This means that higher resolutions are limited to smaller XY build area.

Laser 3D printing generally has a fixed laser spot size of about 300 um, while the DLP projector in the Titan 1 can be customized to print from 37 to 100 um. Tuning the laser spot size smaller will make the printing speed extremely slow. On the other hand, since lasers sweep a continuous path, they’re less likely to show surface “pixelization” artifacts the way a DLP 3D printer printed model will. The pixelization is usually more noticeable for large prints. Pixelization can be removed with anti-aliasing or pixel shifting.

MAINTENANCE

Laser based SLA 3D printers require a number of moving parts in their design. XY motion is achieved via the use of two stepper motors to move the laser itself, or a galvanometer which rotates a mirror assembly to reflect a stationary laser’s light to the desired location. DLP 3D printers do not require any mechanical XY motion for photopolymer curing since projector illuminates the entire XY plane at once.

The Titan 1 and Titan2, with patented passive self-peeling technology, only require one stepping motor for Z-axis linear stage, eliminating the need for sliding or rotating tray mechanisms. This minimizes assembly complexity, maintenance, and wear on the machine.

After 16 months of development, Kudo3D is proud to announce the launch of Titan 1, a DLP SLA 3D desktop printer, which represents a major breakthrough in printing speed, size, and resolution. The launch, which took place at 8:30am PST, was met with a great deal of enthusiasm, reaching its funding goal of $50,000 within 2 minutes. In 12 minutes, they had received $100,000 in pledges. Within 10 hours, that had more than doubled. Their Kickstarter campaign ended on June 26th and they managed to raise an impressive $687,116 to begin setting up production for the Titan 1.

The Titan 1 was well received due to its unique position in the market. Personal 3D printing has been limited by slow printing speeds, small sizes, surface smoothness and constraints on the resolution of the finished product. The industry, which did not exist just a few years ago, has already shown its great potential; Fabricators and designers alike currently use 3D printing for a variety of products and functions. However, industry growth has been limited due to the sheer cost of acquiring and maintaining the existing 3D printing systems.

Kudo3D’s innovation addresses all these problems by incorporating a unique technology on a modularized system. “In order to differentiate our product from the other 3D printers on the market, we had to invest in some practical as well as technological innovations,” Tedd Syao, Ph.D., founder, explained. To address cost concerns, as well as reliability, Syao also took a page from the book of Henry Ford. “It was crazy to me that all of these expensive systems were being built without modularized components.” Key components of Titan 1 include a HD 1080p DLP projector, an industrial grade linear stage module, open-source controlling circuits, a stepping motor, a fast leveling build platform, and Kudo3D’s patent-pending flexible passive self-peeling (PSP) resin container.

The printer can accommodate projects up to 9½ inches in height, making it the most accommodating unit on the personal SLA 3D printing market. Beyond the impressive size of the print envelope, Titan 1 uses a patent-pending technology to permit a level of detail unavailable on most 3D printing systems while still maintaining the flexibility to print large objects. The flexible PSP resin container comprised of 6 different materials was devised to minimize the separation force of a cured layer so that fine features, even those as delicate as a strand of hair, can survive the printing process.

Currently Kudo3D is solidifying relationships with suppliers, locating space to set up assembly, and continuously testing resins to increase their product offerings to backers and future customers. They are planning to begin taking pre-orders for the Titan 1 via their website in the near future.

San Francisco, California- After 16 months of development, Kudo3D is proud to announce the launch of Titan 1, a DLP SLA 3D desktop printer, which represents a major breakthrough in printing speed, size, and resolution. The launch, which took place at 8:30am PST, was met with a great deal of enthusiasm, reaching its funding goal of $50,000 within 2 minutes. After 12 minutes, it had reached over $100,000 in pledges. Within 10 hours, it doubled to over $200,000. The success of Titan 1’s launch can be attributed to its competitive advantage over its competitors.

Personal 3D printing has been limited by slow printing speeds, small sizes, surface smoothness and constraints on the resolution of the finished product. The industry, which did not exist just a few years ago, has already shown its great potential; Fabricators and designers alike currently use 3D printing for a variety of products and functions. However, industry growth has been limited due to the sheer cost of acquiring and maintaining the existing 3D printing systems.

Kudo3D’s innovation addresses all these problems by incorporating a unique technology on a modularized system. “In order to differentiate our product from the other 3D printers on the market, we had to invest in some practical as well as technological innovations,” Tedd Syao, Ph.D., founder, explained. To address cost concerns, as well as reliability, Syao also took a page from the book of Henry Ford. “It was crazy to me that all of these expensive systems were being built without modularized components.” Key components of Titan 1 include a HD 1080p DLP projector, an industrial grade linear stage module, open-source controlling circuits, a stepping motor, a fast leveling build platform, and Kudo3D’s patent-pending flexible passive self-peeling (PSP) resin container.

The printer can accommodate projects up to 9½ inches in height, making it the most accommodating unit on the personal SLA 3D printing market. Beyond the impressive size of the print envelope, Titan 1 uses a patent-pending technology to permit a level of detail unavailable on most 3D printing systems while still maintaining the flexibility to print large objects. The flexible PSP resin container comprised of 6 different materials was devised to minimize the separation force of a cured layer so that fine features, even those as delicate as a strand of hair, can survive the printing process.
Titan 1 is a completed invention, and Syao hopes to use the funds from Kickstarter to open an assembling line in California. The Kickstarter campaign launched on May 27th 2014, and can be viewed at: kck.st/1h9gFwZ.

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Ref.
Tradition Chinese Version PR (329K, pdf)
Simplified Chinese Version PR (287K, pdf)
Korean Version PR (250K, pdf)

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Special thanks to these media outlets for featuring the Titan 1!

1. Locate 3D models online

There are many websites providing a variety of 3D files you can download for free. If the file extension is not ‘stl’, you would need a 3D software to convert the model to stl format. “Thingiverse” is our most favorite site, because most of the files contributed are in stl format for free. We look for 3D models with higher resolutions to avoid limitations posed by the image itself. We use 3D Eiffel Tower as our main testing model for tuning printing parameters of our machine and our PSP (Passive Self-Peeling) mechanism. We have printed more than 80 of them with different sizes. The tallest one is about 9.4 inches, whereas the smallest one is 3.5 inches tall with pillars as tiny as a strand of hair.

2. Check and fix files

All downloaded 3D files need to be checked before slicing and printing. A lot of them may even require repairs. Check your STL files to ensure:

• all objects maintain “outside” orientation.
• the surface of all objects is closed and there are no overlapped faces.

We use “Netfabb basic” to repair models. If the number of shells is too high or “Netfabb basic” fails to fix the model, you would need to upload the stl file to “Netfabb cloud” for further repair.
Sometimes, multiple shells could get you a problematic hollowed model in the following step.

3. Hollow 3D models if necessary
Most of the models require hollowing to save printing materials. In addition, hollowing minimizes light exposure area and greatly reduces layer separation force. The printing time is thus shortened and the printing quality is enhanced.

We use “Meshlab” to hollow our 3D models by building a smaller offset model with inverted surface.
(To Be Continued….)