This week was an exploration of a number of different technologies/digital fabrication techniques which don’t fit into the standard Fab Academy curriculum. I opted to explore the digital embroidery machine so I could tackle this week’s assignment quickly and spend time developing my final project, but I also sat in on a few of the sessions our local instructors gave on the other technologies available in our lab. I’ve given a brief summary of those workflows below as well.
Assignment
- Design & produce something with a digital process (incorporating computer-aided design & manufacturing) not covered in another assignment
- Document the requirements that your assignment meets
Hero Shots
Embroidery Machine
As I mentioned about, I chose to explore the digital embroidery machine available in our lab for this week’s assignment. I set about creating a rose patch.
The embroidery machine we have here in Fab Lab BCN is the Brother Innovis NV870SE
File preparation
There’s a specific open-source embroidery machine extension to inkscape called Ink/Stitch which we use in our lab to create design files for the machine.
Inkscape + Ink/Stitch extension
There’s also another program/option for generating embroidery machine files called Turtlestick. You can create designs using code blocks- it seems very cool from the brief demo we saw but I didn’t explore more on my own this week.
The process for using the machine, and selecting settings, is very well documented by a previous Fab Lab BCN intern, Julia Gaese.
Design considerations for the embroidery machine:
- Details won’t carry over if too small
- Be thoughtful about layers (don’t want more than 2 layers of stitching or could cause a tangle)
- be clever with combining shapes/objects
- employ boolean operations to get one section per color
- can have multiple colors but have to change the thread manually
Following the documentation, I prepared my file on Inkscape:
- Selected a raster image of a rose I liked on Google
- Performed the Trace Bitmap operation to get a vectorized black & white verision of that same rose
- Clean up the vector shape using Path > Simplify
Sizes
This seems like a good time to make a note of the sizes. The embroidery machine works by performing automated stitching inside machine-specific embroidery frames. There are supposed to be four frame sizes that come with our machine but at the time of this writing only two were available/present:
- Small (13 x 14 cm)
- Large hoop (I don’t know the exact dimensions))
In Inkscape I changed the document size to 13 x 14 cm so I would design inside that area.
Initially I actually set the size to 13 x 18 cm, and then was confused when I exported my file because I kept getting a message from the machine that I needed to use a larger embroidery frame for my design. When I fixed the size, I was able to send it to the machine!
Using the Ink/Stitch Extension to set params
Since I converted my design from a raster image to a vector, I followed the additional recommended cleanup step in the Ink/Stitch Extension:
- Extensions > Ink/Stitch > Troubleshoot > Cleanup Document
I wanted there to be a border around the edge of my patch, so I added a diamond shape and converted the outline to a Satin column.
Then in Extensions > Ink/Stitch > Params I set my stitch settings.
Because I have a Satin Column in my design, there are several different options for an underlay within the Params window. I opted for the Zig Zag.
I used the default option for the Fill stitch.
Export
- save as .pes to be read by embroidery machine
- save on thumb drive to transfer file from computer to embroidery machine
Embroidery Machine Setup & Stitching
General notes:
- two different hoop sizes, select the one you need based on design. I designed for the smaller one.
- use a backing for the fabric (specific backing material for embroidery)
- Can also use felt (don’t need the backing)
- use special needle for heavier fabrics like denim (or risk breaking the needle)
- not all threads are created equal. Use a thread that’s strong and resistant to snapping
- can rotate, scale (to a certain extent), mirror, and move the design around the workspace via the machine’s display
I chose a nice dark red thread which others seemed to be having success with, threaded the machine, and set it to work!
Reflections
I really enjoyed working with the embroidery machine, and had to stop myself from working on more iterations of this rose patch (rather than working on my final project..). My next iteration, I want to use multiple colors, something like this:
I have so many other ideas! But I need to spend my time wisely, and that means continued explorations with the embroidery machine will have to wait.
At the beginning of the week the embroidery machine was acting up a bit- we were seeing the thread from the bobbin on the surface of the fabric, which shouldn’t happen, and it seemed to be tangling and creating knots. We did some troubleshooting (and also took the machine apart a little bit…). Ultimately, we found that unwittingly we’d used the wrong shaped bobbin, so once that was addressed the machine was running much more smoothly. Not sure why the wrong type of bobbin was near the machine in the first place but.. I digress.
In our tests and troubleshooting we also found that not all threads are created equal. Certain threads were more “brittle” than others, breaking more easily. But the deep red thread I used in my design was one of the threads that performed very well; it was quite strong and resistent to snapping.
Design Files
Other Possible topics for Wildcard week
- Composites
- multi-axis machining
- waterjet cutter
- plasma cutter
- vacuum forming, rotomodling
- folding: origami
- robotic arms: building construction, soft robotics
- machine learning in embedded systmes: OpenCV, tinyML
- food: 3D printing, 3D machining?
- textiles: automated embroidery, smart clothing, wearables
Composites
- one of most underused processes, in Neil’s opinion
- examples:
- concrete w/ rebar
- adobe: clay & straw/fiber
- carbon fiber: bikes, airplanes
- paper mache
- wood
- an example from my own field: heart valve leaflets (support fibers inside very stretchy elastic tissue)
- combine two materials to leverage the favorable properties of each- can achieve very strong, very light objects
- in the concrete example, rebar handles tension, concrete handles compression
- consist of a fiber and a matrix material
- fibers Natural fibers: cotton, silk, bamboo, linen, burlap, wood
- matrixs epoxy, plant resin, sugars, concrete, wax
- techniques/terminology:
- laying up plies
- darts so fabric will lay smoothly in the mold
ideas: bike helmet, shoes, laptop case
Large format CNC
- 3D large format CNC
- using ball-nose endmill (only need one tool, can perform both roughing & finishing without needing to change)
- needs to be long enough to reach the depth of the cut without colliding the spindle with the stock
- 2 passes:
- roughing
- finishing
- (optional) second finishing operation
- 2 1/2 axis profiling to cut out shape after
Robotics
We also have several 6-axis robots at the lab. Students at IAAC use them for architecture and/or construction projects- you can add any end effector you want. Our local instructors gave us a bit of a crash course/introduction to the theory behind using and designing for the 6-axis robots so those who wished to could use them to draw designs in light.
Key concepts:
- Coordinate systems: Important to know which coordinate system you’re using
- World, robot, tool, stock/base
- Inverse kinematics to figure out joint angles needed for the end effector to reach the target point
- Can define different types of movement
- PTP: joint interpolation (faster but lets machine decide movement)
- Arc interpolation
- Linear interpolation
- Singularities = positions robot cannot achieve - will need to pause and realign
Terms:
- Work Cell
- Work envelope - all space a robot can reach
- degrees of freedom
- payload: how much weight a robot arm can handle
- end effector - tool that does the work of the robot
- manipulator - robot arm (every thing accept end of arm tooling)
Safety & control: Flexpendant
- flexpendant is the controller used to control the robot
- robot only works if button pushed 1/2 way down - safety feature
- not pressed, stops (if operator drops)
- pressed all the way, stops (if operator gets electrocuted & hand clenches)
- if want robot to be autonomous, needs to be in an enclosure (for safety)
Design files & principles
- create curve for the robot to follow, and break the curve into a series of target planes for the robot to orient to
- need to define planes rather than points in file, so the end effector will hit target in the correct orientation (there are many ways it could reach a point, but a plane is more defined)
- beware of crashing the tool into the robot
idea from my field: fabricate a complex 3D shape like an aorta?
Precious Plastics
Fab Lab BCN also has capabilities to process and reuse plastic waste using tools and techniques from the Precious Plastics project workflow.