Foundry - Polygons in Bronze: Part 3

As I mentioned in my last post, my workspace is too cold...

To mitigate this cold, I have placed my printer inside of a hydroponic grow tent... I'm sure my neighbors thought I was using my garage for something other than 3D printing... luckily, no one asked questions.

The grow tent, along with the possibly dangerous inclusion of an infrared heater allowed me to get some semi-successful prints, pictured here. After the first print, I met with my instructor to go over some areas that would need to be changed specifically for successful bronze casting (like the thin ear tips). Now that I had my sculpture sitting in front of me, I could more easily see areas in need of improvement and went back to work in ZBrush.

I printed another cat. This one checks most of the boxes, but has some printing flaws that I have deduced to be caused mostly by the still sub-standard ambient temperature. Time to find a better solution.

On the MSLA (Masked Stereolithography) printing process:

For those unfamiliar with what is most commonly referred to as "resin printing", this form of 3D printing is used mainly for non-structural components that require the finished piece to retain detail with minimal sanding and finishing work. A metal buildplate moves along a Z-axis, dipping into a vat of UV-sensitive liquid resin. The metal plate stops about 50 microns from the bottom of the vat which sits atop an LCD screen. The screen acts as a mask (think adobe software masks or a physical stencil) and allows UV light to shine up, through the screen, and into the vat of resin. The resin between the plate and the bottom of the vat, if hit by the UV light for a few seconds, is transformed into a solid. The plate raises up, the now solid resin layer (again, only 50 microns thick) detaches from the flexible vat before the process is repeated for hundreds or thousands of layers.

Once the printer finishes with the final layer the printing process is complete (of course). However, this is where the real work begins. The resin may be solid now, but it is still coated in uncured liquid resin. The print must be washed using alcohol such as Isopropanol, Ethanol, Methanol, etc; I use 91% Isopropyl Alcohol because it works and is readily available while being slightly less odorous than another readily available alternative like methylated spirits/denatured alcohol. (Note: Some resins can be washed with water, but I've found that those resins tend to end up more brittle so I don't use them.) Once the part has been washed, it then needs to go through a process called post-curing. To post-cure a resin print, you just need to let it sit out in the sun for a few hours or inside of a UV light chamber for a few minutes. This finishes curing all of the resin so that it is safe to handle.

NOTES ON PPE: Uncured liquid resin, depending on the chemical composition and on an individual's skin sensitivity, can cause rashes or burns if not immediately removed. Some individuals may not have such a strong reaction to uncured resin. That being said, by introducing these chemicals to your skin or inside your mucus membranes (inhalation of fumes) your body can become sensitive to the different polymers that make up the resin. This increased sensitivity presents itself much the same as an allergic reaction. Therefore, by mitigating one's exposure to uncured resin, one will be less likely to develop a sensitivity to it. Since I plan on working with these materials for a long time, I want to make sure that I am lowering my exposure as much as possible. Apart from the resin, the large quantities of alcohol can cause unpleasant fumes that will irritate your lungs, throat, nose, and eyes. Because of all of this and the fact that I am working in a space without good ventilation, I wear a full-face respirator and nitrile gloves at all times when working around these chemicals.