Sunday, January 16, 2022

little robot with the Hummingbird bit


Little robot is a steal from Tom Lauwers Birdbrain technologies site.

The key idea is to place 2 position servos to obtain flexible neck movement, both left / right and up / down. Follow the link for detailed instructions on the Birdbrain site.

SOME CODE
Here is some code, using variables, to control the robot's head movement using the arrow keys (I wrote some separate code for the video):
Here are some rough notes about what I did, some mistakes I made and how to do better next time:
  • Use a bigger box to make a 7.5 cm cube box
  • Need to screw into the servos. I forgot and it fell apart.
  • Add duct tape to first servo to stop it moving (photo)
  • Add duct tape to servos and servo horns so they don't become glued up (photo)
  • Mark face position on the bottom cube to avoid confusion
  • A smaller thickness of hot glue might work better than big blobs (I read up on hot glue guns)
  • When attaching the top cube hold bottom firmly on RHS and press the top cube in, not too hard, in the correct position on the LHS (initially my positioning was all wrong)
  • Leave significant gap for head movement b/w top and bottom cubes (otherwise down movement will be restricted)
  • Leave RHS bottom door open until everything else finished. I still haven't closed it.
  • Calibrate optimal rotations when coding (if you rotate too far you might break it). I settled on left-right 10 to 170 and up down 65 to 115
Extra equipment:
  • Small screwdriver
  • ifixit blade for prising off dry hot glue when you have to redo
  • Super scissors
  • ruler 3 inches = 7.5 cm
  • duct tape
  • masking tape
  • googly eyes
Related:
Would you like to see a toilet roll dance?
bee waggle project with the Hummingbird bit

Organising a 3D printer building activity

This is the printer I built from a kit.

After considerable research I bought an Original Prusa i3 MK3S+ 3D printer. There are thousands of 3D printing companies out there. My first consideration was the open hardware / open software criterion. Prusa is part of the RepRap project (humanity's first general purpose self replicating machine) so they went onto my short list. Then Prusa has the best reviews so I was sold.

Through talking to teachers who use 3D printers I became aware of their main limitation for school use. They are slow. Even a simple print takes about 20 minutes so with the setup and remove the print time added on you will only see one student print their design in a normal lesson.

So, I floated the idea of families buying a kit, students assembling them at school and the family keeping the printer. Everyone I mentioned this to almost immediately said “great idea”. So we sent the invitation out to the school community and so far eight families have come on board.

The advantage of this plan is we get 3D printers into the school community without having to worry about the slowness problem. And to build a 3D printer is a really good step towards understanding how they work.

I needed to get a head start on this so I found a company in Australia, 3d Print Specialist that sold the kit. It arrived just before Xmas day and then the fun really started!

We are advising the parents to buy from Czechoslovakia, it is cheaper that way, but there is a considerable lag time.

It says on the Prusa that their fastest customer built the MK3S+ in 4 hours!! Ha ha. Well, I guess I'm their slowest customer. My rough estimate for my build time was 75 hours! I certainly didn't rush!

The build instructions are on the Prusa site:
Original Prusa i3 MK3S+ build instructions
Original Prusa MINI+ build instructions

The instructions are very well thought out, colour coded with pics, with numerous warnings in red. Fellow builders from the community leave comments at each step, which provide essential further help. Of course this arises from the open hardware and software ethos of the Prusa community.

It gave me hope to find out that others found it hard, some even found it harder than me!

In the end I was successful! The last, testing stage was nerve racking since some of the tests take a while. Then when I got to first layer calibration I wasn't confident since I had to nudge the z axis since the test print wasn't sticking on the sheet. Really I just did this by guess and test and it came our correctly after a couple of guesses. Here's my just about perfect test print:

Without going into all the detail I'll mention some of the techniques I learnt along the way since these will be valuable to pass onto my students later:
  • don't throw anything out prematurely
  • screw seating technique, watch this video from Alex
  • how to exert force without breaking the part (force and support at the same time)
  • use the grease out of the bearing bags to grease nuts that are hard to fit and the rods before sliding into the misumi bearings (one reason not to throw stuff out once used)
  • use of AA battery or flat side of screwdriver to push in the belts
  • extruder cable sorting technique (one comment was very helpful here)
  • bending the zip ties using the pliers and wrapping around

The toughest parts of the build are the extruder and fitting all the cables into the too small Einsy box (lots of complaints from the builders about that). I'll show pictures of those parts so you are forewarned!
Here is a ridiculous video showing a young girl, Aurora, building the whole thing in 38 minutes

Monday, January 10, 2022

understanding Omicron

In looking for authors who *understand* omicron I haven't found anyone better than Eric Topol. I was hoping to summarise but other things got in the way. Below are a few links to recent substack articles. To follow him regularly his twitter feed is here
March 7: The Epidemic of Covid Complacency
Feb 10: Separating Facts from Myths in the Pandemic (interview, 32 minutes)
Jan 30: A Shot in the Dark
Jan 23: Where do we stand with Omicron?
Jan 5: Humans 2 Omicron 1
Jan 10: We are very lucky
Dec 16: Why Paxlovid is a Just-in-Time Breakthrough
Feb 2021: Variant-proof vaccines — invest now for the next pandemic

Monday, January 03, 2022

ozSAGE Omicron alarms

An ozSAGE recent report (December 30th) about Omicron warns us not to become complacent in the face of the "it's mild" narrative. Well worth reading the whole thing here

Some key points:
  • Hospitalisations in Australia are increasing sharply, see the graph on page 3 (although their text seems inaccurate about ICU increases which the graph shows are small)
  • Health systems are likely to be overwhelmed, especially in regional centres
  • NSW is already warning people not to expect access to hospital care (doesn't this mean that our health system is already overwhelmed?)
  • Omicron variant is at least as virulent as the original strain of COVID (this is a key point, obviously it's complicated and requires more evidence and context - but sounds like bad news for the unvaccinated and otherwise vulnerable)
  • long COVID affects brains, heart, kidneys (link provided)
  • medical staff burnt out
  • GPs expected to carry the burden for failing hospitals - not realistic
  • Boosters required urgently but it's not happening quickly enough (I read elsewhere that astrazeneca which most elderly people received only provides 6% protection from omicron)
  • Expect increased deaths for vulnerable groups (the elderly, low socio-economic groups, first nations people)
  • Children hospitalisations have increased in both the UK and the USA

Sunday, January 02, 2022

books I am reading in 2022

BOOKS and some articles 2022

Bhattacharya, Ananyo. The Man from the Future: The Visionary Life of John van Neumann (2021)
Blikstein, Paulo. Travels in Troy with Freire: Technology as an Agent in Emancipation (2008)
Harvey, Brian & Monig, Jens. SNAP! Reference Manual 7.0 (2020)
Newell, Barry. Turtle Confusion: Logo Puzzles and Riddles (1988)
Ridley, Matt. How Innovation Works (2020)
Stager, Gary. 20 Things to do with a Computer: Future Visions of Education Inspired by Seymour Papert & Cynthia Solomon's Seminal Work (2021)
Thornburg, David. Learning to Code: An Introduction to Computer Science Through the Art and Patterns of Nature. Snap! Edition. (2021)

Previous: Books 2021