week 4: 3d scanning + printing

Prior Experience: 1/5

I have gotten my teeth scanned at the dentist before...and I have 3d printed before, although the model I printed I took off of Thingiverse. I was vaguely aware of how 3d printing worked and various principles such as overhangs and supports.

This week, we learned about the possibilities of 3D scanning and printing. (Side note: apparently people have figured out how to 3D print with sawdust (https://3dprinting.com/news/new-3d-printed-wood-is-all-wood/) and it looks shockingly similar to tree wood. That's insane.)

3D Printing

(I didn't end up getting the model to print but here's a render of it.)

Idea

What should I 3D print this week? The assignment is to print something that cannot be made subtractively.

I decided to model and print a "ship in a Klein bottle." In particular, the Klein bottle is a non-orientable manifold, which means that it's not possible to pick an "inside" or an "outside" in a consistent way. If you try, and then walk around on the surface for a bit, you will eventually go from the inside to the outside, or the outside to the inside, without crossing any boundaries.

So technically if you have a Klein bottle and a ship, regardless of where the ship is, it is as "in" as possible.

I wanted to put a "mesh" or pattern of cutouts so that it is possible to see inside.

CAD Modeling: Ship In A Klein Bottle

This one says it is "basic cad modeling" for "absolute beginners"" https://www.youtube.com/watch?v=lMLatDq0JqU

I got confused so I gave up and looked for another tutorial.

I started to follow Tina's tutorial: http://fab.cba.mit.edu/classes/863.18/CBA/people/tina/portfolio/week04_3d/

1. sketch the wide bottom portion
2. revolve the sketch
3. create the neck path
4. sweep
5. loft (i need help here) a. i couldnt figure out how to make it tangent like tina so i just gave up and demircan said to fillet it. so i did. b. it created a weird surface that looks like some noneuclidean monstrosity. c. turns out I need to reduce the radius of the fillet
6. here i was following the steps in tina's tutorial but for some reason fusion was a. getting mad that I wanted to intersect while sweeping and b. not letting me shell the klein bottle!!! so i was very sad.
7. i ended up (with demircan's help) unstitching the different bodies (which i think converted them to surfaces), then thickening the surface
8. had some issues but ended up with (probably?????) a klein bottle

I went through a lot of different iterations for the klein bottle, etc. etc. a;skfj ;lasfj dl;ksj f

Holes in my klein bottle

I wanted to put holes in my klein bottle since after 3D printing it is not possible to see through the material, unlike the glass material in Fusion 360.

This was slightly painful. Demircan sent me this tutorial for making a hexagon pattern: https://forums.autodesk.com/t5/fusion-360-design-validate/sketch-on-curved-surface-or-boolean-a-pattern-on-a-curved/m-p/6030445#M45375

I wanted to do this but I could not at all figure out how. I ended up trying to do this "orange slice" pattern and then cutting that out of my current model.

I had a lot of issues with cutting the handle of the klein bottle, and I couldn't figure out how to get it to only cut the body.

I think my CAD abilities were severely limiting what I could actually end up with but I figured out how to pattern the sketch and then cut it out. I literally just deleted the triangles that intersected the handle too much so that they wouldn't cut out the entire thing.

Boat

I had several boat iterations. (I am struggling through the CAD but it kind of works?)

I ended up making a "paper boat" in Surfaces, and then using Thicken to make it actually 3D.

Render of the ship in a Klein bottle:

Here's one with a small ship "inside":

Here's one with holes:

3D Printing the Model

I went in to the shops to get trained on the 3D scanner. The Sindohs are intended for self-service use; here is the archshop tutorial: https://archshops.mit.edu/sindoh.php.

First, I exported my Fusion 360 models as .stl files and uploaded it to Dropbox. (I wanted to print a version with the holes and a version without the holes in the Klein bottle.)

Then, I opened it on the shop computers on the 3DWOX software, sliced it, and exported it as g-code.

I kept getting an error from the Sindoh saying "this G-code cannot be printed from 3DWOX 1," even when I only processed and loaded the sphere (rather than the Klein bottle or the ship). It was annoying.

Returning to the 3D Printer

I came back to print. Apparently the issue is that when I export the gcode on the computer, I need to tell it which specific 3D printer to use.

I uploaded the Klein bottle again, and then i click on layer viewer, and then adjust the slider to see the wall thicknesses. Cool! with the mouse wheel, zoom in/out, and with the right click you rotate around, shift middle click gives u cool interior stuff.

To add more supports, go to Settings, and in Support, select placement everywhere. Also, go to settings, and printer settings, and set the printer model to DP200 (works on the black ones) or 3DWOX1 (the white ones).

Here is the Klein bottle!

I also printed the Klein bottle with holes and the ship, and it turned out pretty cool :D I got lots of compliments on it in my math class, since people liked the Klein bottle. (Picture to come --- I left it in Edgerton so I don't have it now.)

3D Scanning

Here is the archshop tutorial: https://archshops.mit.edu/scanner.php

We have a Revopoint. I downloaded the POP2 software. https://www.revopoint3d.com/download/

I connected it with USB.

Test 1: Fast Scan Initially it didn't work. I put the scanny thing on a turntable and the scanner on a tripod so it is more stable.

I scanned it and saved it as a .obj file. Fusion does not like to open the .obj file. Turns out you have to mesh it.

Click on the mesh button. It doesn't let me export. I give up let's try a high accuracy scan.

Test 2: High Accuracy Scan

It scanned properly and is fusing the point cloud.

I clicked "open" to export (we got confused but apparently open means export) and exported it as a .stl.

I can open in Fusion!

How To Print Your Mesh

• make mesh waterproof in fusion
• export as stl
• slice the stl using 3DWOX
  • go to printer settings and use DP200
  • File load model and load the STL, click "layer viewer" and it will process for a while. after that check how it looks. then save G-code in a flash drive. then plug it in to whichever 3d printer i want to use.
• then click the file it will give you a warning. say yes etc. then it will prepare for a while and then once it starts you can take your flash driv.
• important: wait until it lays down the first layer to make sure it works.

Group Assignment

The group assignment this week was to test the design rules for the archshop 3D printers.

Izzi printed out tests for lots of parameters.

Supported overhang: The test printed out fine.

Clearance: A clearance of 1 was necessary to allow the squares not to stick to the bar. Angle: The angles all looked good. Unsupported overhang: Bridging: The printer could handle all the lengths. Wall thickness: The printer had trouble around 0.4. Surface finish: The finish of the spheres looked good.