NineLizards: Frankenblocks Concept

So, I decided to create my own STEM system. Step number one was the decision to adapt and adopt Lego bricks. Step number two was figuring out the concept and sizing.

I got some input from an Internet contact who is a teacher, so I used quite a bit of his insight and input. (He didn't want to be mentioned, but you still deserve the credit, mister X! We'll call you 'Fred' from now on.)

Step by step

So... step 1: what's going to be the basis of our own 'STEM' system?

1. Lego. Everybody has some left over bits hiding in the odd corner.

Note that the whole Frankenblocks idea is in no way a challenge towards the Lego copyright. I just use the term Lego here to indicate that my intention was to make all modules as compatible as possible with regular Lego bricks.

2. Design and print some test pieces

The first thing to understand is how Lego is properly dimensioned and printed, and see if I can print some accaptable, compatible pieces myself. There's a lot of engineering that went into those little bricks. Way more than you would expect - do a bit of Googlefu and marvel at the science behind it.

I did investigate in calibrating the printer to get optimal results, but to be fair: little of that was necessary when using PETG on our Bambu printers (Fred has a P1S at his school, I own an X1C myself).

I bought some Lego Technic compatible stuff on AliExpress, as my own pieces were more than thirty years old, and some bits had become quite brittle. (Everything orange is 3D printed, everything non-orange has been bought.) Suddenly, I have a box half full of gears and bricks and other funny stuff. I even added some motors and servos...

I could never afford this back in the days...

(Click image to enlarge)

3. The previous steps have proven that Lego is a usable basis, so what next? Let's think it over... Modularity is the name of the game, so we need to create modules. Modules that can be combined with Lego pieces.

That means we may end up with simple 'lego' plates, or elements oriented towards Lego Technic. Perhaps we create a module that works as a power supply, or one that carries a breadboard, a servo motor, or an array of sensors.
Anything we made that carries some open electronics (a microcontroller, a breadboard) I'll call a 'carrier plate' from now on. If it's a full, self contained unit, it's a 'module'. I hope I'll remember that 😅

Sometimes it is easier to plug modules into breadboards, and sometimes you just want them in different shapes and sizes for other projects. We wanted to support both approaches.

4. Make all modules stackable, where possible.

It's a kind of Lego - euh, magic 🤔 - after all...

5. Lego is made of injection molded ABS. For simplicity I've decided to print everything in PETG. ABS might have been a better choice, but it stinks up the place, the fumes are not that healthy, and it suffers from delamination.

I print most of my PETG in Orange. This is a kind of 'reference' color in my own projects, so I can quickly identify what kind of plastic it is. The ABS I have laying around is mostly black or white. I do have some FR PETG and other stuff, but PETG is my prototyping material of choice.
For the 'carriers' with sensors and other electronic bits and pieces I plan to use sky-blue PETG. The only reason is that I bought a few rolls of blue PETG when I couldn't get orange. There actually is a practical aspect to that as well: all regular blocks are orange and can be treated 'badly' whilst the more sensitive bits will be carried by 'blue' plastic. Hmmm... not intentional, but it might work out for the best.
You may notice multiple colors of orange, but that's because I experimented with different brands of PETG. Thus far, Bambu, Jayo and Sunlu are my favorites (and they might actually all come from the same factory). Geetech... not so much. But my printer could use it (just using generic PETG settings, using the X1C autocalibration). It prints slow, but it works.

You may have to adjust your printer to get everything properly sized, especially when printing ABS. I've dedicated a post to calibration. On a side note: it wasn't really necessary on our Bambu printers...

Warning - PETG is a bit risky when it comes to glue! If you plan to glue the stuff, either go for contact glue (Bisonkit or similar) or use another material.

It should not be necessary to glue anything, except for the 'low' version of the tray, and you can do that one using contact glue (Bisonkit). More about that later.

Bits and pieces

So, now it's time to do some more orange magic... (everything black is bought, everything orange is 3D printed)