Notes from Robert's Lesson

Robert started by explaining what a slicer is. A slicer is a coding environment that creates an instruction set: move print here at this speed and this temperature. You have your C code, but you need a compiler which is your STL file but you need a compiler to make it into specific instructions that your machine can interpret. The diagrams I have referenced are from Obsessively Geek and are not my own.

How do SLA printers work?

SLA stands for steriolithography which is also the same thing STL stands for. This method uses lasers to cure photopolymer substrate. There is a tray of resin and lasers cure this photopolymer substrate one layer at a time. Underneath it traces the layer and so it seems like it's being pulled out of the resin. SLA printing can do some shapes much better than FDM. Downsides are cupping, supports, and attach points. Supports are somewhat obsolete... SLA printing uses attachments to make sure the object doesn't fall from the build plate. These attachments aren't supports.

How do FDM printers work?

FDM stands for Fused Deposition Modeling and it is the most widely used form of 3D Printing. FDM is actually trademarked so alot of printers that say they are FFM are just dodging patents. Imagine you have a hot glue gun and want to make a model... you lay hot glue down... wait for it to try... and then lay another layer down. A solid role of filament is fed through a hot cartiridge and then through a heated nozzle and then laid down in a predetermined path.

This printer does not melt carbon fiber. There is a razor blade in the print head that cuts this material. Parts must be optimized to wide enough to run fiber ... the more concentric circles you get the stronger the part. This is great for making something tortionally strong - twisting. This wouldn't stand up to crushing forces. It's anisotropic...? Different properties in different directions.

How do SLS printers work?

SLS stands for Selective Laser Sintering. SLS uses a bed of feed material which is sintered together with a laser. Kind of like melting it. The downside is toxicity, clean up, etc. An upside is that you can pack parts three deminsionally which means it lends it self well for a 3D printing farming. On a microscopic level SLS molecules look like metal barbed wire and for that reason they are very bad for your health.

Let's print!

At the onset of this week, I thought I would make an instrument like a shaker... so I would start the print of a sphere with no infill, pause it, add coffee beans, and the resume it... then I realized that wouldn't end up getting used for anything. Then I thought about the plants in my house. Some are in containers with holes. When I water them, I have to take them to the sink or tub and keep them there for hours until they fully drain. So I thought to make a planter with a repository at the bottom to collect excess water. There are tons of these that you can buy and actually some stls ready for printing exist as well. But none quite my style.

First model...

So, there are a few reasons why I think this would be impossible to create subtractivley. The angle of the base of the pot, the text inset on the side and the holes. The internal holes (for drainage) are easyiest to see in the transparent CAD drawing. The connect the but separate the top componenet from the bottom and are somewhat precarious which is why the first few pritns failed.

Printing on Fabric

There are several innovative techniques for printing on fabric and I thought I could try out the "sandwhich" one. I don't really think this could be make substravtively... though maybe? I more did this because it's a different way to use a printer. But imagining a CNC router trying to cut around delicate fabric... does seem somewhat imnpossible.

3D Scanning

3D scanning is a process of collecting data from the surface of a physical object which should describe the shape in terms of three-dimensional space. A long time ago, I used a kinect to do this and it worked ok but I ended up needing to take the file (which was massive) into a post process software to retopologize it. Retopology is the process simplifying and clarifying polygons and is typically what is necessary still for many 3D scanners. In the lab we had two different ones, neither or which I had any luck with. I have documented those issues below. Ultimately I chose to use a free app on my phone and I was amazed by the results. I ultimately was heppy I went with the process beacause if you have a phone (that's not too old) you can do this which makes acces and potential for equity much higher than buying a $100, $500, or $5,000 scanner.