Week 2 : Stacking and Nesting With Affine Transformations

This week we used affine transformations to generate nesting 3D forms in Rhino/Grasshopper, sliced the results in Cura, and printed small prototypes on the Ender 3 Pro.

• Rhinoceros 6 (Mac)
• Grasshopper
• Ultimaker Cura 4.13.1
• Creality Ender 3 Pro
• Hatchbox Silk Light Blue PLA
• Blender

My approach is generally to follow the tutorial exactly to make sure I am getting all the basic functionality before moving onto the fun and creative steps at the end. I ran into some syntax issues when it came to the "Duplicate" stage of the tutorial. I was able to scale and orient the cube based on the relation of the two points of the target curve, but was unable to make an array with the "count" slider.

I was getting stuck and frustrated, so I decided to move onto the next example codes in the tutorial. In this later example, I was able to generated nested arrays with the "count" slider, so I continued from this point. I spent some time manipulating the existing input curves to get the wavy pots (seen above), but I still wanted to get more complex and interesting results for my final models. I thought 3 was a good target for a printed prototype, but i included a screen shot of an array of 20 vessels to demonstrate the "count" function. At this point, I skipped ahead to the final example code where things got interesting and dynamic.

At first, I attempted to bring the entire baked geometry of one of my Week 1 models into the patch, which was so complex that the resulting geometry just looked solid. I eventually realized that Professor Jacobs' example was generated with just a simple wave curve as the source, so I started modifying that curve to see if I could get any interesting results. I compressed the curve and made it loop back on itself (seen in image 3), which generated some interesting geometric results. I exported the first result just to make sure I could successfully export something. After exporting this initial test, I went back in and adjusted the parametric sliders to get a more subtle result, which I was happy enough with to attempt to print. I unstacked the models in Rhino and exported them as three separate STL files. I wasn't sure how, or if, this delicate form would print, so I took it to the Cura slicer next.

My STL files are too large to attach here.

I separated my resulting Rhino models into 3 STL files (small, medium, and large). I started with the smallest of my 3 nesting forms for my first test print. I decided to print with a raft to help those delicate first layers adhere, and I generated supports to help the hollow forms and overhangs at the top. I wasn't sure how hard the supports would be to separate from such a delicate and tiny object, but I was quite impressed by Cura's default support settings. I experimented with different nozzle temperatures and quality settings (detailed below).

I was so excited to have access to a 3D printer that I got started with calibration tests as soon as I received it!

I leveled the bed using the paper method that Professor Jacobs showed after class, and got a good first result on the xyz calibration cube with the white filament that came with the printer. I printed one of my STL files from Week 1 in this white filament as well. I had some bed adhesion issues on a corner of this print, but I trimmed the mistakes off.

I had ordered SILK PLA on my own, so as soon as that came, I started printing tests with it. I made a xyz calibration cube first, which came out well. I'm really interested in the "lightning" infill option in Cura (for it's aesthetic possibility as well as time/material saving), so I did two tests generating lighting infill on a short cube and stopped the prints before printing the top layers. There are some very interesting optical effects when this is backlit, and I plan to keep exploring it this quarter. I'm interested in exposing these generative mathematic structures that aren't normally supposed to be seen.

One issue I ran into was bed adhesion on the corners of my model. At first, I was working with my studio windows open, which I think may have unevenly cooled the print, and led to some expansion/contraction. Eventually this worked itself out, but it causes the bottom corners to curl up slightly, which compromises the finish of the prints. I started increasing the nozzle temperature for the SILK PLA, and I used a raft for this weeks prints. I'm unsure whether I should increase the bed temp from 60˚C at all. I should do further calibration tests to find the best slicer settings for my different filaments.

I bumped the nozzle temperature up to 200-210˚ for these SILK PLA prints (the spool says Ext Temp: 200˚-220˚C). At first, I was assuming these values were measured in F, but this week I realized that they are actually C.

I printed my first test of the smallest model at 200˚C following the SILK PLA range (200˚-220˚C). I wasn't sure if I should change the bed temperature, so I just left it at 60˚ C. I used "Standard Quality - 0.2mm" for the first print, which came out ok for such a small model. I wasn't sure how hard the supports would be to remove on such a delicate model, but they actually came off surprisingly easily. There was one small break, but I just need to be more careful in removing supports. Overall, I would say the first test print was successful.

I printed the largest model next, and switched the quality to "Super Quality - 0.12mm" to try to get a smoother finish. I also bumped up the nozzle temperature to 210˚C to see if that would help quality, but this model appears to have even more stringing. I'm not sure if this is a temperature or line quality issues yet, but I am leaning to it being a nozzle temperature issue.

I split the difference for the medium model, and returning the nozzle temp to 200˚C and choosing "Dynamic Quality - 0.16mm". After this print, I would say that 200˚C prints better than 210˚C. I should do some small calibration cubes all at 200˚C with the four different quality settings to see how noticeable the difference is.

I will not have time this week, but I would eventually like to print one of these models at a larger scale to see how smooth I can get the surface finish.

Final renders in Blender using glass shader, HDRI, mist, and lighting effects to make up for stringy 3D prints.