# week 05

3D Scanning and Printing

## 1. Group assignment:

### Rhino + Grasshopper：Test Model

The group projects is 「Test the design rules for your printer」

• How sharp design can you make？
• How thin wall can you make ？
• How small gap can you make ？
• dimension？
• Actual size and design size ?
• So I planning to build a "Test model" by Rhino, moreover, Grasshopper can help me do a set of models with arithmetic progression. I hope it looks smart and simple.
some thing like below:

### Research and Practice

I searching "Rhino Grasshopper Arithmetic" final I found this [Tutorial]

After that I improve the original program a little bit, made "how thin wall" & "How small gap" into one single model.

Than I try to build a model to test "How sharp design can you make", my plan was to make a series lines with different angles.
So google searching "grasshopper rotation line array", I found this [Tutorial]

However, the results doesn't show that satisfactory. Eventually I get back to the old way.

• Draw a straight line and rotate the angle with the command: 「rotate」
• Cut the block with the command: 「wirtecut」
• Then get to the curve and the tilt angle of the printer.

### Print test model out

I use a FDM 3D printer print our Test model, which is a DIY type 3D printer design by our co-founder Xuan, relatively low accuracy,around 0.2mm.
Unfortunately, when I print, my「fill」was setting too low, 12%, to print out a flat plane. thus the entire base is full of holes.

We use 「Repetier」 to do layering and setting
But when I import「.stl model」,software reminds me that there is an error:

`The model is not manifold...`

So I google it and figure out It was because I didn't pay attention to the following questions when I model:

• 1. The model must be manifold
• 2. The model must be closed (Watertight)
• Explanation
• My final choice was this 「Netfabb」 a Microsoft's online 3D repair website, Done.
• Open「Repetier」setting fill: 12%
Temperature: 210°
Click: 「layered」
Then copy to the SD card and start printing, export.

Comparison the design size and actual print size
Total length: Design value 129.5mm / Print 128.5mm
The finest point is: 0.95mm x 0.71mm
The minimal gap: 0.52mm
The thin wall: 0.66mm
Block width: Design value 15mm / Actual 15.07mm
Extreme tilt angle: 50°

## 2. Individual assignment:

### Ex-Rings

In the previous 「Computer-Aided Design」week, I made a Ex-ring by "Antimony".
This week I printed them out by a STL 3D printer.

The stl models that exported by the default parameters of “Antimony”, all show a broken surface and the effect was not yet satisfactory.

The reason was finally found out because the default setting of the export parameters is too small, only 50.
Later, I solved the problem by raising the export setting to 200 but file size also soared from 16m to 130m.

### Process & Details:

First I tried to rebuild Ex-ring with 「libfive」

• Install 「libfive」
• Than I import the default example which is normal and you can edit it. But unfortunately my own model is always wrong. Due to time pressure, I could not find a solution to it.
• ### Print out:

• So I used Antimony to make a model again. Exported STL file, than designed a pendant in addition to the previous ring.
• Reduce some complex surfaces with 「Reduce Mesh」 command in 「Rhino」 before printing. I also checked the broken surface ,manifold & Watertight for each model
• After checking it, I load the model into layered software. Confirm once again whether the model surface is complete
• Because I use a STL 3D printer, I added a lot of support to ensure the final print quality.
• Adjust the position and set the size