A few months ago I switched over to Eco UV Resin as I wanted to be a good citizen of the planet, and thought that moving to a plant-based product that is water-soluble was the right thing to do. I’m on my third Kg container of this product, and I’m beginning to have my doubts, but perhaps I should back up.
In March of 2020, I purchased an Elegoo Mars 2 Pro 3D resin printer, and have consumed at least 15kg or more of standard resin in at least four colors, so I’m not your typical 3D resin noob. I also picked up an Elegoo Mercury Plus wash station at the same time, and typically wash 20-40 prints per gallon of 97% alcohol. To be clear I’m not printing small figures, but more often than not 3-5″ models of things like custom Raspberry Pi cases, fan mounting brackets, and prototypes of future products. So when using normal resin the alcohol in the washbasin will become discolored after a few washes, but I don’t switch colors much and the prints are always clean, smooth, and free of any residual resin after washing. In fact, often the rapid resin stays in suspension in the alcohol between print jobs, sometimes a week or more without settling. I’ve found that washing with less than 97% leads to stickier prints and the alcohol becomes contaminated faster due to the additional water. Some suggest curing suspended resin in the wash tank by leaving it out in the sun for a bit, then filtering it. Recently, I started using translucent clear plant-based resin, and the experience is considerably different from that of rapid resin.
When I finish printing with translucent clear Eco resin, I put the build plate with all my printed parts into a tank of soapy water in the wash station and run it for twenty minutes. The build plate is then removed, parts are separated from it then scrubbed to remove any trapped resin the wash station missed. Next, the supports are snapped off. One further scrub, some light sanding, and another rinse then on to curing. Seriously, I’m probably consuming a few gallons of water per print, and wash my hands several times thoroughly throughout the process. No, I don’t wear gloves, and this has never been a problem for me as I’m extremely careful, and what resin which has come in contact with my skin has never caused a problem. After I’m done, I then need to wash and scrub out the wash tank and build plate. This is far more labor-intensive than alcohol-soluble rapid-resin where I never clean the model outside of what the wash tank has done. It should be mentioned that I often print hollow models, and very carefully place the drain and vent holes so they are hidden, yet offer the best functionality. Trapped resin is rarely an issue. While Eco resin sounds environmentally friendly, when one takes the volume of water consumed into account it may not be as friendly as it appears.
Today my $500 setup has a limited print volume of 5” x 3.2” x 6.3” and can produce a full-size single color print in under eight hours, often careful placement means two to three hours. Other products in this 3D printer line are bigger and capable of print volumes nearly triple mine, but they are still single color. Producing a final product that has multiple colors requires multiple prints for the various different colored parts, then you need to assemble them. Between colors, the tank needs to be emptied and cleaned. Designing something from scratch that screws or snaps together requires some serious modeling and slicing skills, along with the professional version of the slicer. A slicer is a program that takes your 3D model and turns it into a file your printer can understand. Even more important though, the slicer helps you layout your model on the build plate, detect and fix print problems with the model, make some adjustments, like creating weep holes and vents so that resin isn’t trapped inside hollow parts, and define supports connecting it to the build plate. How, and where to place supports for a 3D model with a resin printer requires different considerations than a traditional deposition printer. So where is 3D printing headed?
3D Resin printers often utilize a 4K monochrome computer screen that faces up from underneath the build tank. A UV light then shines through the screen and cures resin wherever there isn’t a negative print image. Initially, the slicer produces a raft that is a flat surface on the build plate with a lip around the edge that enables sliding a scraper underneath the raft when the printing is done to separate the print from the build plate. Supports then grow out of the raft and connect it with the model. Models are often suspended five to ten millimeters below the build plate with these supports enabling them to be easily separated from the raft after the build is completed. Once the printed model is rinsed and separated from the build plate then you need to remove all the supports, further clean the model, and often sand the surfaces where supports were attached to remove any pitting. Does this sound user-friendly? It isn’t, right now it’s something that only a devoted hobbyist or employee would leverage to achieve an objective.
Many of us can envision a day when we order a product on Amazon, and while it’s in the cart Amazon checks the supplies in our home “Amazon Replicator” to determine if the proper color resins and cleaning supplies are available to build the product. If so then the order is accepted, and sliced print files for my model replicator are automatically downloaded and queued into the printer. When the parts eventually emerge in the product hopper, along with one-page assembly instructions, the customer is then charged for the print and additional replacement supplies are shipped out when necessary. The customer then assembles their product and they have what they ordered in hours rather than days.
Today we pour 200 ml or so of a single color resin into the tank then print a single color until the job is complete. What if the printer sprayed an appropriately thick layer of a specifically colored resin onto the tank bottom, for the layers needing to be printed next in that color. Then between layers requiring a color change, the tank bottom could be cleaned, drained, dried, and the new color sprayed thick enough for the next layers requiring that color. When the print is completed the tank would be drained, cleaned, and dried for the next job. The build plate and the print would then be fully washed. At this point, simple robotics would be needed to separate the print from the supports coming up from the raft using one of several types of tools to clip, melt or vaporize support resin where it meets the model. At this stage in the process, the model is dropped into the curing bin for a few minutes then released into the output bin. Meanwhile, the raft and supports are recycled, perhaps back into supplies or for return to Amazon for reprocessing. With advances in modeling, slicing, and printing we may eventually reach this point for some simple products, but given my experience, this is still a number of years away.
Regardless, it’s awesome to think that even today we can take an idea, create from it a 3D model, then slice and print it all in the same day! I really love technology.