Sunday, 9 October 2016

Cheapest 3D Printer

My latest obsession is trying to build a 3D printer for as cheap as possible.

Partly it's because I believe 3D printing is a disruptive technology. The lower the cost for making a 3D printer, the more people will have access to the technology, and sooner the disruption will take place.

And partly, it's because I'm just really really cheap.

Low Cost

What does low cost really mean? One obvious way is to look at the price of something if we were to buy it new in a shop. If we only source new parts and new materials, we're going to have a difficult time creating something truly low cost.

My strategy is different. I'm going to try and get as many of the source materials as possible for "zero dollars."

Consider old car tyres. Any time you can recycle the rubber from an old car tyre into a seesaw or a swing, or into building materials or to protect a wharf, then the cost of that rubber is effectively "zero dollars."

That's why the core design elements of my 3D printer are going to be fishing line and lego. Two very cheap substances if you source them the right way.

Fishing Line

Nylon fishing line is an amazing substance. It's strong. Durable. Inexpensive. It's readily available everywhere around the globe. And if you need small quantities, you can often obtain it for "zero dollars". You probably already have some.


Lego is an amazing substance. It's available everywhere. It's manufactured to extremely high tolerances. It's consistent across time and place. It comes in a variety of colors. It's durable.
While lego might not be cheap, you can often *borrow* lego for "zero dollars" by using the magic words "I'm trying to make a 3D printer out of lego."
Once your print run is complete, you can simply disassemble the lego and return it to it's previous state.

Calibration Problem

When I look at the designs for existing 3D printers, one of the biggest design considerations seems to be finding out where the extrusion point is in relation to the "bed". Existing designs carefully measure the motion of the motors, try really hard to make the frame rigid, and then have lots of complicated software to try and calculate where exactly the filament is being deposited.

Ack, too difficult.

Why go through all the calculation, when you can measure directly?

My plan is to use the camera on an Android tablet to see where the bed is, and, at the same time, to see where the print head is. If it needs to move to the left, well, the tablet will keep the motors spinning until it lines up. Too far to the right? no problem, spin the motors the other way until it matches. Checkmate calibration problem!


Oh, and remember our lego? We know exactly how large a block is in the real world, so we can measure off distance in our 2D camera space by placing a known lego calibration object made with a few different known colors.

This way it doesn't matter if our fishing line stretches during the course of the print, or our lego gets bumped half way through, or the ambient temperature changes which make the layers a tiny bit thinner.. no problem, the camera on the android tablet sees all.

And how much does it cost for an Android tablet? "zero dollars." You just have to use the magic words: "Can I borrow your Android tablet to make a 3D printer?"

Next Steps

I've already starting on version 1 of the prototype. Watch this space.

Saturday, 1 October 2016

ELI5: What are the differences between the C programming languages: C, C++, C#, and Objective C?

"Hello World" in C
C, C++, C# and Objective-C are all programming languages. They're all special ways of writing where a programmer can ask a computer to solve problems for the programmer.

Don't be fooled by the letter “C” in their names, the 4 languages are actually quite different.

C is the oldest of the 4. It was one of the first really popular programming languages because it was good at solving the types of problems that programmers had way back in the 1980's. Things like “portability”, “memory management” and “correctness”.

C is quite a simple language, which means you need to do a lot of writing to ask the computer to do complicated things.

C++ is actually C with lots and lots of extra stuff added in. It's name is a pun, where to the computer, C++ means something like “better than C”. And yeah, there's other computer languages with pun names like “D” and “F#” too. Because C++ is a lot more powerful than C, you don't need to write quite so much stuff to get the computer to do complicated things.

Objective-C is also C but with different stuff added into it. Both Objective-C and C++ try and help programmers solve tricky problems using something called “Object Oriented Programming” (OOP). That's where the “Objective” part in Objective-C comes from. OOP was really good at solving the kinds of problems we had back in the 1990's.

OOP is so successful because it helps teams of programmers work together and co-ordinate. Any time you have a large group of programmers working together, especially on the very largest software projects, you'll find that they're using some version of OOP to help them all co-operate.

Because both C++ and Objective-C have a shared history in C, if you wanted, you could take a C program and pretend that's it's C++ or Objective-C and most of the time that might even work!

What really happens though, is that because the languages are so different, it changes the way that programmers think about their problems. This means that C programs, C++ programs and Objective-C programs all end up looking quite different from each other, even when programmers are trying to solve the same problem. ( See also: Sapir–Whorf hypothesis. )

Which brings us to C#. C# isn't really a C language at all. There's actually another programming language called Java that used to be really popular around the year 2000 because it helped with the OOP problem much better than anything else. A company called Microsoft wanted to make something that was kind of like Java, but kind of different too. So they created C# to work a lot like Java, but changed things up a little bit so that it looks kinda like C if you squint.

Well here we are in 2010's, and the kind of problems programmers are facing have changed again. It turns out that using OOP can sometimes combine with other problems to make them more complicated, graphics problems like “threading” and “latency” or the special problems that come up with Artificial Intelligence for example.

While we have newer languages like “Cg”, “R” or “Python” that try and address some of these newer problems straight on, it turns out the simplicity of C allows individual programmers to focus more clearly on the problems that are important to them. That's why C is still popular today, even though it's the oldest of the 4.

TL;DR: C is really simple. C++ and Objective-C are kind of similar because they're both C with extra stuff for “Object Oriented Programming” (OOP). C# is the oddball because it isn't really a C language at all, it's more like Microsoft's version of “Java”.

Source: Am programmer.