Impact of Background Curing

How does background curing affect the print or the printing process? During the printing process, the resin under background exposure keeps accumulating photons. Once the number of photons received per unit area reaches the threshold dosage, the resin will start turning into solid.
Have you ever seen bits of resin flakes attached to your print? This is a physical example of background exposure affecting your print. The reason for this is because the resin close to the printing zone is being cured slowly by both the background exposure and the scattering light from the pattern. Once the resin in the region near the patterns accumulates enough photons, thin layers attaching to the model may form and get separated from the Teflon film (as shown in the Photo 1). Sometimes, part of the layer could drop or remain at the vat floor (as shown in the Photo 2). A model that requires a longer time to print is more likely to form these flakes. The worst case scenario is when a fast resin is cured by the background light, it could stick to the vat floor firmly and pull your model out of the platform or even break your model into two pieces.

Even if you do not see the flakes on the print or within the pool of resin, the background exposure still affects the resin you are printing with. The background exposure partially cures the resin near the vat floor in the build zone. This will have an impact on the printing parameters of subsequent layers. Because the resin has already absorbed some photons, curing it with the normal exposure time will actually mean that the cured resin is being over-cured. As the liquid resin accumulates photon gradually, the resin will slowly become more viscous than before and the printing parameters may change.

It should also be noted that the exposure time scaling is not linear. The resin curing is an ongoing reaction even after the light is off. The faster the curing speed the more ongoing reaction. Therefore, fast resin or stronger light tend to have more ongoing reaction. In general, we have seen resins with exposure time less than 1 second are more likely to form solid background cured flakes.

The Solution to Background Exposure

There is no way to achieve infinite contrast ratio for DLP, but there are ways to reduce the background exposure during the printing process. This is where the shutter from the Titan 2 and Titan 1 Upgrade Kit plays its role. The shutter will remove the background exposure when the platform is moving for separation. (This is the time where there should be- ideally- no light being shined upon the resin.) With the shutter, the accumulated number of photons absorbed will be greatly reduced. The adhesion between the cured layer and the Teflon is then more predictable and the lifetime of recycled resin will be extended.

Another way to reduce the impact of background exposure is to lift the platform higher so more ‘fresh” resin will be sucked into the printing zone and dilute the resin that has been exposed under background light in the print area.

For the same resin, increasing the build size to increase the exposure time will reduce the background curing effect. As a result, you may see the background cured flakes appear at 37 or 50um XY resolution but not at 75um for the same resin. Using a shutter will alleviate this problem. Sometimes, the background curing is caused by the video card. For Titan 1, if you use Nvidia display adapter, it is likely that you will experience background curing. Using an Intel built-in video adapter will solve this problem. For Titan 2, video adapter of Raspberry Pi does not have this issue.

This blog will guide you through and help make sense of each feature on the sample.

1. Rectangular columns and spaces (Slots)

To determine what the “normal” exposure time is for a certain resin, check the 4 rectangular slots on the leftmost side of the calibration print. The columns in-between the slots should have the same measurement for the first 4 on the left side. The width of each slot and column should be 0.8 mm. The width of the right most three slots are 0.6mm, 0.4mm and 0.2mm, respectively.

Too narrow of the leftmost opening will mean that the resin was overexposed. Too narrow of the column in-between will mean that the resin was underexposed. If the resin does not have a high resolution, have high viscosity or the XY resolution is not high enough, the right most slot may be closed.

2. Pillars

Take a look at the pillars on the left side of the print. To make most of the pillars protruding and present, the resin will need to be very hard. Hard resin or overexposure will increase the number of pillars printed successfully. This is because the pillars will be hard enough to overcome the gravity at an angle of 45 degrees. Hardness and the strength of the resins will determine whether the pillar will survive at the angle or not. Another thing to note is the diameter of the pillars. Thicker pillars are stronger and tend to survive during printing even if they are longer. If printing with a low resolution resin, light bleeding makes the pillar thicker and also change the shape of it. When a higher resolution resin is used, more holes are opened and the pillars will be closer to the original dimensions. However, thinner pillars may not survive if the material is soft. Therefore, for precision applications, you would need to use a high resolution hard resin.

3. Holes

Take a look at the 7 holes below the rectangular slots on the “Titan 1” side. Hole openings are influenced by the viscosity of the resin, the depth of the hole and the ability of resin to block light. To make all 7 holes open up, the resin may need to be underexposed. Overexposing the resins will result in the smallest few holes to close up due to light bleeding or scattering. With a resin that has a lower viscosity, there will be more holes open. Because the resin is more likely to drain out of the hole during printing, light bleeding is less likely to seal the hole. However, low viscosity resins in general have more monomer in the formula so the material tends to be weaker and more brittle.

4. Trenches

Check the trenches near the top of the “Titan 1” side of the print.

We limit the aspect ratio of the trenches to be one so the depth and the width of the trenches are the same. Having the resin be overexposed will result in a narrower, shallower trench. An underexposed resin will further widen the distance between each trench. The reasoning is the same as that for the slots and holes.

Given all this information, the questions is: When do you need to print this calibration print again? We usually recommend doing the calibration for the following situations:

1. Using a new type or new bottle of resin
2. Printing at a different XYZ resolution
3. If you regularly recycle (pour the leftover resin from a print back into the original bottle) the resins without replenishing with fresh resin
4. Every 500 hours of usage of the projector (to determine if the projector lamp intensity decays)

You can measure the size of the features on the high resolution calibration model with Netfabb basic by pressing the “ruler” button. For actual printed sizes, you would need to use a camera or microscope and take a photo of the printed sample with a benchmark.

This calibration sample only gives you an idea about the exposure time, the resolution and hardness of the material. The lifting height is related to the resin, lifting speed, cross-sectional area and cross-sectional pattern so there is no calibration sample to predict the lifting height. If you are not familiar with the resin used, please be more conservative about the lifting height and speed.

Now, you are ready to continue on your printing journey! Please be sure to share any awesome prints with our team as well! Have fun!

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.

While staying true to its original Titan 1 base – a patent pending passive self-peeling (PSP) technology, the Titan 2 has new upgrades that provide a more user-friendly experience, including wireless connection and web-based controlling software. We also add a shutter to reduce background exposure to extend resin lifetime and a mask option to make the intensity more uniform. At the same time, the new mesh-like build platform reduces the vacuum force between layers and make printing a lot easier. We are always dedicated to improve our 3D printing technology to meet the demands for different applications.

Apart from the technical aspect, we have always been trying to improve the user-friendliness of our printers. It is easier to install and configure Titan 2 now. Titan 2 is WiFi enabled with built-in Raspberry Pi 3, so it doesn’t need to connect the printer to the computer and it will be independent from the user’s computer. Only one power cord is required to run the Titan 2. The new web-based controlling software is compatible with PC (windows, Mac, Linux) or device (smartphones, tablets). One PC or device can be used to manage multiple Titan 2 which is helpful for those who would like to use the printer to setup a production line.

Pushing the printer to the extreme, Titan 2 can print fine features that no other low cost SLA printers can achieve. In the image taken by a microscope below, a 45 micron thin needle was printed with the Titan 2. This needle is less than half the diameter of a strand of hair.

The new Titan 2 body will be fully assembled and calibrated, making the start up process even easier for first time users. Also, to celebrate our new release, there will be a $200 USD discount on the Titan 2 for anyone placing an order before June 19, 2016.

What are you still waiting for? Don’t miss the chance to experience the most advanced technology brought to you by Kudo3D now!

(** The first shipment of Titan 2 will be on July 6, 2016. Please feel free to contact our team members for more information.)

Erik Moon, one of our Titan 1 Kickstarter backers and owner of Decadent Minimalist, has just released his second Kickstarter campaign, DM1: Titanium and Carbon Fiber Wallet!

The DM1 is truly a minimalist design. With no straps, no clips, no clasps, hinges, or magnets, the DM1 is just one piece of aluminum cut into an ideal shape to hold multiple cards. Now, the DM1 has a 12 card option and is available in Carbon Fiber, Titanium, and Nickel.

Erik captured his first prototype of the DM1 by filming the printing process on the Titan 1. He explains how he transformed his DM1 idea into an actual product.

Watch to see how the Titan 1 can quickly transform an idea into a prototype!

Titan 1 was featured on an article on Stereolithography by Eaglemoss Publications!

Learn more about how light causes photoresin to cure. Also enjoy the pictures of prints by the Titan 1!

In the past, post-processing a print was a long labor-intensive process full of sanding and grinding in order to achieve a professional finish. With the Titan 1 DLP SLA printer, the 3D prints are produced with a smooth professional finish, greatly reducing the energy and time required for post-processing.

Thanks to Kudo3D’s patent-pending separation technology, less supports are required for printing, which means less cleanup and scarring. Rings can be printed with the Titan 1 without internal supports and only require one support at the base of the ring.
Ring by Smita Lai. Only one support on the bottom.

The image below is a great example of how the Titan 1 reduces or even eliminates post processing. No sanding was necessary, preserving the fine details of the miniature. In addition, with layer heights of 35um, the horizontal lines that usually define each layer are invisible.
“Froggy” by Spectoys printed with Titan 1. No sanding necessary. Prints can also be casted or painted afterwards.

We have simplified the post-process down to 4 easy steps with very little equipment needed.

To post-cure you only need a few over-the-counter items including:

• 91% Isopropyl Alcohol (IPA) or Rubbing Alcohol (99% IPA is better, and it is available on Ebay)
• Containers large enough to submerge your print in
• Disposable gloves
• A pair of pliers
• UV light

 
1. Remove the print from the platform using a blade or other sharp tool. Please be careful not to slip and cut yourself.
 
2. Next, submerge your print in a container of Isopropyl Alcohol (IPA) for 3 minutes. Then, swirl it around in the IPA to rinse off extra resin. Alternatively, you can use a squeeze bottle to rinse off extra resin. This step removes the uncured layer from the print, helping to reduce any residual stickiness.
RichRap’s Voronoi Tower http://www.thingiverse.com/thing:24123
 
3. At this point, your print should have very little to no stickiness left on its surface. Next, gently remove the printing supports with a model cutter. It is easier to detach the supports closer to the tips, since the supports are pointed.
Depending on how precise you need your print to be, you could leave a tiny stud of the support tip attached to the surface to avoid making a dent. The protruding tip could then be sanded down. Pulling the support out or cutting very close to the attachment point creates risk of leaving a small dimple behind.

Jennifer Chen’s Flower Design
 
4. Use either Kudo3D’s UV-post curing lamp or direct sunlight to complete the final curing process. The amount of time needed to post-cure a print depends on its size and the post-curing method used. Using a clear container with tap water to submerge the print is optional but shortens the curing time needed.

Post-curing with Kudo3D’s UV lamp

Submerge the print in a clear container filled with tap water. Place the container under the UV lamp for about 5 minutes. If the print still feels uncured or sticky, leave the print under the UV lamp for a few more minutes.
 

Post-curing with Sunlight

Submerge the print in a clear container filled with tap water. Then place the container under direct sunlight for about 15 minutes. If the print still feels uncured or sticky, leave the print and the container in the sun for a few more minutes.

 
The purpose of post curing is to dry up and harden the outer surface of the print. Oxygen in the air diffuses into the outer layers of resin while printing, preventing the print from fully curing. Submerging the print in water forms a water barrier to prevent oxygen inhibition since the water prevents oxygen in the air from reaching the part during curing. This allows the UV light from the sun or a lamp to cure prints faster. Post-curing without placing in water will take much longer. This process mainly cures the surface of the print. Interior structures will continue to cure slowly over time due to ambient UV light exposure.
 
With the Titan 1, you can spend more time designing and printing and less time post processing!

Recently, we decided to put our Titan 1s into overdrive. We were stunned by the results! We knew that we were being conservative in our speed estimates, however, the print speeds we achieved were truly amazing: 7 inches per hour!

We printed this chiral two-layer geodesic sphere with a diameter of 2 inches in 17.5 minutes. Watch the sphere materialize in the video below!

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!