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Mitalee Parikh authoredMitalee Parikh authored
3D Scanning and printing
This week I made some 3d printed tools and 3d scanned using photogrammetry.
I wanted to make simple tools this weeks, so I experimented with simple joint mechanisms. Some references that I used to develop my designs:
- Compliant Mechanisms Research (CMR by BYU)
- Why machines that bend are better
- Compliant mechanisms by Devin Montes - video
- These transformed chopsticks
Design
I first made a scaled-up version of a simple Gemclip and some other simple geometry clips. I bent one end to add a dimension, that does not allow it to be made using only one subtractive method.
I first made it in 2D in plan to the size and proportion I wanted, and then extruded it in Z. Later I bent the inner part so that the model could no tbe made only subtractively easily, as now it had an undercut.
Then I used some parts of these tranformed chopsticks reference above that I found
And then made normal tweezers and then modified the geomtry to make it compliant like the chopsticks above.
The models
Gemclip by emaitee on Sketchfab
Next after, watching some videos on making compliant mechanisms, I made a simple pick-and-place plier to test out the bending.
Some tweezers we used for holding down electronic components:
Simple tweezers by emaitee on Sketchfab
I wondered if it was easier to use the tweezers with a reversed action, where applying force releases the object. And by default it holds the object. For this, I used this mechanism designed by Devin Montes - video and transformed it for the tweezers.
Creating toolpaths
I used Cura to make toolpaths for my 3d prints. I uploaded my stl files, set my machine, choose PLA as my material and used these settings:
Printing
I used an Anycubic Kossel Plus 3D printer to print with a black 1.75mm PLA filament.
Printing the gemclip: The finish was alright, as the first layer spread a little too much, causing it to be broader then the actual form. The first layer has a layer height of 0.3mm, and all the consecutive ones were 0.15mm. I used a cutting blade to finish these edges.
In the next print, I used the same layer height for all layers. I printed a simple pick and place plier using a bent compliant joint.
Simple nose-end tweezers:
Used the transformed chopstick geometry, modifoed it for the tweezers: 
The bending details were too small, they broke while I was trying to clean them up.
Overall, I made some small experiments with simple tools. I hope to remake the tweezer with the semi-compliant mechanism again after modifying the design.
Useful reference:
Design for 3d printing tutorials
For next time
If I can have more time on the machines I can modify the mechanisms by trying out various different tollerences, size and setting. And maybe make a small set of complaint mechanism tools.
Photogrammetry
I used Agisoft Metashape to make a pointcloud. I followed this tutorial by Agisoft.
I clicked 53 images of the object on a plain background from all around. Steps to make a pointcloud:
- Workflow > Add photos
- Workflow > Align Photos (this step take some time depending on the number of key point limit and tie point limit you set.)
- Some photos failed to align, but I got 9003 points
- Workflow > Build dense cloud - medium quality.
- Workflow > Build Mesh
- Workflow > Build textures
The process: 
The output:
Nut and bolt by emaitee on Sketchfab
3D Scanning
I used a Roland Modela MDX-20 to scan the same object. I used the step-by-step manual for this. 
Stuck the bolt and nut using a double sided tape on the raised level bed. 
I set the scanning area, as close to the object as possible. And a scanning grid of 0.5mm on both X and Y axes.
The output: 