The Beast cometh!

For many years I wondered why no-one seemed to make wheeled robots with stepper motors. It seemed an obvious option to me but it was always small DC motors (or large ones of course) or altered servos that everyone used. While in my self imposed quarantine, I started reading up about steppers and I can still find no reason not to use them so...........

My Next Big Thing

is going to be an attempt to build a four wheel drive robot using stepper motors.

I'm not using large motors either, I shall be using 28BYJ48 motors with their associated driver boards because of their size, small, and their cost, cheap as chips. I have already run some tests and, whilst fairly slow, they are very strong with good torque and should do well for what I intend building.

Rather than drive them from a big complex system, I am going to try using Arduino Nano boards, one to each motor, and network them using I2c to either a Raspberry Pi or another Nano with a WIFI link. I'm not too clever at coding for the Pi so I will certainly begin with the Arduino.

I've begun by drafting  out a basic  concept for the body of the vehicle itself.

As it will be a four wheel drive chassis I want it to be fairly symmetrical with the wheels all the same size and only steering at the front end. It has to be big enough to carry all the electronics but not too heavy to be driven by the somewhat small motors. 

I also would like it to be fairly high above the ground in order to be able to take advantage of the large, 85mm dia, wheels and the high torque they will have.

And lots of prototypes are being printed for the body and moving parts.

Sadly, none of these will make it to the final product but most of the measurements are now fixed.

Sidebar #2 How I did it.........

The case is made of two 3D printed pieces, Front and Back with three 3D printed buttons. The box on the left is for a five volt power supply and that takes it's supply from the fig.8 socket mounted on the rear panel. The small hole is for the alarm sound to be heard. In addition, I have cut a small piece of acrylic that fits the display panel to keep dust out and make the whole look fairly professional, I hope.

Sidebar #1 My Alarm Clock Part One

I couldn't resist this.

A board I ordered from China arrived this morning and I felt the urge to produce a case for it. I could have built a "Multi System" case (spoiler alert there) but decided to go for a more traditional one.

So here are the beginnings of my new alarm clock.

Its the SFT-CK302 bought from Ali-Express sitting on top one of my PSU#2 units.

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Well, it took a while but I have done all the design work and built the case.

However, I am not considering it finished until some tools I have ordered from China arrive and I can polish the case before sticking it together.

And the next big thing is...............

I have been using these little stereo amplifiers for quite a while now and have been very impressed with their quality. I also wanted to build an amp / speaker system for my computer that would sit quietly under my 4K monitor. I had all the components I needed but it would require a suitable set of boxes to house the whole thing.

And that's exactly when the idea was born.

When I was a lad, a very popular toy was Meccano. For those who don't know about Meccano, or for North American readers, an Erector Set, it was, and indeed still is, a set of component parts that bolt together and can be made into all manner of working models.

I began to design a set of parts that would, together, be easy to assemble into a standard case for electronics that could be 3D printed at home.

I learnt a lot from that exercise, not least that it was expensive printing all the trial bits only to find that my clever idea #23 didn't work any better than the first iteration.

Nonetheless, I have persevered and have now learnt enough to have produced the two speaker units and an amp / MP3 player unit and they work!

Power supply #2

The first power supply was fine at a technical level and it also looked pretty good too but I wanted to have another crack at the concept from a new perspective and also my new skill level with the design software.

I remembered that I had bought three of these little beauties some time ago and it would be a good idea to check them out.

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      I also had a new colour to print with and I was keen to give it a try. So I designed another power supply that used a 12 volt buck converter instead of a 5 volt one and carefully designed a new case to take the USB board and also a 12 volt DC socket as well.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      

       The results were very satisfying but I also realised that I wanted to use this colour again.

And, at that time, the Next Big Thing was born.

Show us yer Tesseract?

What is a Tesseract?

It's a long tale about what it is so, if you really want to know, just click on the link above.

Ann explained what she wanted to me and it sounded fairly easy so  I said, "Oh, I can knock that up quite quickly, come back in a weeks time". The following day I designed and built the top of the box with translucent filament and it looks superb. I had the design of the base worked out in my head and built a rough version to test the sizes out and then went straight in and built 

the base and the display carrier in one afternoon. I had ordered the battery holders already and they arrived that week fortunately. The other components were already in stock and I got the whole Tesseract built in just six days.

Ann loved it and so we were all happy. And it was about now that the vague idea for the next big thing began to take shape.

Sibling rivalry........nearly

You may have gathered that I live in the UK,

I have, however, a very close friend who is American and lives in the state of Georgia. We have been friends for so long, it almost seems like forever and as we also share many interests it sometimes happens that a bit of rivalry creeps into our relationship. Just before Christmas 2019 I received a parcel with a little electronic gift that Todd had made for me.

Based on a Raspberry Pi Zero, it has a small screen that plays a series of photos of our last holiday with him interpolated with  inspiring messages.

It was really great and I kept showing it to family and friends all through Christmas.

In fact, the only minor problem was that Todd had needed to use a case from another project to build it into for safety and looks. And looks were not brilliant as he was at great pains to tell me.

Well, it didn't bother me but I knew I had my Prusa on the way. I also had some fairly extensive knowledge of using Neo-Pixels and that's when it all got a bit competitive.

My idea was to build a very small version of the Christmas display and make it shine through a non transparent case so that, when not switched on, it just looked like a block of white plastic. Making something that small should be a doddle after making power supplies. Well it wasn't. I realised about two days in that I was becoming a bit of a perfectionist. Added to which, I had begun to learn a lot of useful stuff about 3D printing and coding for Arduinos. It took nearly three weeks to come up with the final design but it was worth it as the final product looks very elegant and simple. I shudder to think about the wasted filament but told myself it was all about learning how to do things properly. And then along came Ann and gave me a challenge. "Can you build me a Tesseract?