Lego Mindstorms EV3 Rubik’s Cube Solver

This has been around for a while now. We didnt want to dismantle our existing EV3 kit which was built as a R3ptar so we purchased another set in new and sealed condition from Ebay for about £200.

My partner quickly built the Mindcub3r from the instructions here: MindCub3r for EV3 (mindcuber.com)

It took her a few hours and she left it for me to do the software installation part the next day.

The build was fairly straightforward but I spotted a couple of small pieces that were out of place and corrected these to ensure the model moved as expected. I then downloaded and installed the Lego Mindstorms software and followed the instructions above.

When I ran tried downloading the required software from the PC to the brick it kept erroring and complaining that it could not find various blocks. I wenbt back through the instructions again and realised I missed the step where you install the RGB Color sensor software. This was done and the software successfully downloaded to the brick.

After a quick trip to Smyths toys to purchase a genuine 3×3 Rubiks cube for £9.99, I tried to run the software on the robot for the first time. The brick beeped but nothing happened. After a few basis checks we noticed a low battery icon the brick and replaced the new (cheap) batteires with some Duracell batteries and ran the program again. This time it did its reset procedure and then asked for the Rubiks cube to be inserted. It scanned the cube, did its calculations and solved the now mixed up Rubiks cube.

It works most times but not always and I attribute this to ambient light levels and some movement of the Rubiks cube in its cradle. Over the coming weeks i will try some modifications and see if I can get a 100% success rate. Its still so cool to see it in action solving the Rubiks cube. Now to try to solve it by hand!

Blast From The Past

Just found this little gem. An early raspberry Pi in a wooden Pi Hut case.

Raspberry Pi Model B Rev 1. Serial No: 0000000026aa80b

Still working and running Raspbian Wheezy on a 4GB SD Card. I have fond memories of creating my first projects on these early Pi’s but thank God for the Pi 4 with 4GB RAM, WiFi, Bluetooth etc.

Wire Buzz Game

For one of our College open evenings, I decided to make a traditional buzz wire game. The components I used for the project are given below:

Components needed:

Tools

  • Soldering iron
  • Solder
  • Cutters
  • Wire strippers
  • Hot Glue gun & glue rods
  • Double sided tape pad
  • Insulation tape black.
  • Copper pipe bender
  • Drill, drill & router bits

The copper pipe used for the project was supplied by Ali in the plumbing department who also kindly bent the pipe into a buzz wire game shape. I then drilled two holes into a piece of scrap 2 x 4 wood from the carpentry department and pushed the ends of the copper pipe through the holes. The holes were tight enough that this actually holds the pipe nicely in place although you could also attach end caps and/or hot glue the pipe in place if necessary.

At first I assembled the electronics and tested they worked before fitting into the projects components box. I could have wired everything properly and soldered all the connections but I quite liked the diy project look you get from using a bread board and dupont wires. It can also be easily dismantled and repurposed for future projects.

The circuit is simple and uses a battery box with 4 x AA batteries providing 6 volts. Voltage is supplied from this to the breadboard and then to a toggle switch then a pizeo speaker across to the negative rail of the breadboard which is connected to the handle with a hook.

The positive rail also supplies voltage to another toggle switch, a resistor to limit current and then to a 10mm bright LED and again back to the negative rail and handle/hook.

One end of the copper pipe is then connected to the negative battery terminal with a soldered wire.

The two toggle switches mean that the light and the buzzer can be independently switched on/off i.e if someone touches the copper pipe with the handle/hook then the buzzer will sound only, the led will light only, both will buzz and light or nothing will come on at all.

Once the wiring was complete, I drilled a hole through the wooden base and brought the black lead that attaches to the copper pipe up through it. I also drilled a hole into the black box and pulled the wire through the bottom of this and then screwed the black box to the wooden base to secure it. The breadboard was then stuck to the inside of the box using its self adhesive tape and the battery box was secured inside using a doublesided tape pad.

Two holes were also drilled into the lid of the black box and the toggle switches were pushed through and secured using their nuts. Another small hole was made for the piezo buzzer wires to pass through the lid inside the box and one more hole for the legs of the large LED to pass through. The buzzer and LED were then hot glued into place and the wires were attcahed to the undserside of the lid. The lid could then be closed and secured using its four screws.

The handle was made by cutting an old broom handle down to about 5 inches length and drilling a hole through the middle at both ends. I then took a wooden coat hanger, and removed its hook and soldered a cable to this which then passed through the hole in the handle and attached to the project components box and breadboard. I used a small amount of hot glue to help hold the wire securely in the handle. Crude but it works.

Total project time around 2 hours. I made use of some parts from the College but if you had to buy everything from scratch it would only cost around £30 in total. The final size was about 1m wide (0.75m for the actual pipe part) and about 0.5m tall.

Hictop 3D Printer Repair

My 3D printer had been left in a shed for nearly a year. The shed was so packed I couldn’t really get to it. I finally managed to get it out of the shed a while ago but when trying to print, the nozzle was clogged, I tried unclogging it and the thermistor fell apart, so I decided to get a new nozzle assembly that comes with the thermistor preinstalled. You can easily pick up replacement parts for any Prusa based printer from Ebay and the cost was just £6

After I changed the first nozzle assembly, the printer would not heat up properly and I quickly realised the new thermistor had also come loose so ordered another one. Then I got distracted with Christmas and left the printer.

After a couple of months, I have finally made the time to replace the nozzle assembly, again.

I removed the old one including the thermistor cabling and started fitting the new one running the cables back to the control board. The old thermistor used to have an intermediate connector close to the nozzle but the new one does away with this. It’s all a bit fiddly, trying to hold the print nozzle assembly together whilst screwing it into place but you get there in the end.

Finally, pieced it back together enough that I could try a test print. I have been using an Ultimaker at work for the past week and i’m lucky if I can get one out five prints working first time.

Straight after the repair and with the bed height not properly set, it started to print a valentines model with no problems. Not bad for a £150 printer versus the £2500 Ultimaker.

Halloween Preparations

I’ve started ordering the components to build an animated halloween door amongst other projects. I orderd some parts from the excellent Pimoroni and they had an offer where if you spent more than £30 then you received a “Day Of The Geek” soldering badge kit.

Mine turned up last night and so I had a go at putting it together. It only took me 10 minutes to do although I am struggling to see what i’m doing now these days. Time to buy one of those helping hands with magnifying glass me thinks.

The kit comes in a small bag of components. The funky skull shaped PCB with predrilled holes for the components.

You get a QR code to scan to see the instructions for assembly although its pretty simple.

Push the CR2032 battery holder into its holes (there is a printed guide on the PCB to help you). Solder this.

Then put a large blob of solder onto the back of the skull where indicated and then attach the badge pin back.

Finally solder the two red LED’s for eyes. Steal a CR2032 battery from the bathroom scales while my partner is not looking and hey presto, a Day of The Geek badge.

I’ve had it running on a used battery now for about 14 hours and its still going strong.

Update: Its still shining away on a used CR2032 battery after 36 hours.