Fidget

The 2010s can be divided into two eras — the time before and after fidget spinners came to existence. The weird part is that they came out of nowhere, and now they don’t seem to exist at all!

In fancy MakerSpaces, it is quite common to make these using 4 cylindrical ball bearings, and printing the shell. However, where’s the fun in boring old 3D printing? Besides, it takes quite a while to print. And not to mention, there is always going to be tolerance issues, because low fidelity printers are not supposed to be accurate.

Truth be told, using a thick piece of acrylic and laser cutting is perhaps the fastest way to do this. But a laser cutter is limited to cutting at most an eighth to a  quarter of an inch, beyond which one will have to repeat the trace on the piece of acrylic. And this would cost, surprise, surprise… the tolerance.

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Regardless of the backstory, I was thinking of using multiple machines to make something. The plan was to use my trusty desktop CNC milling machine along with the water jet. I used delrin to make the case or the shell, and the caps. Then, I cut a thick piece of steel slab into circles, to give the spinner some weight.  All in all, it worked exceptionally well!

P.S. I’m not making another one, not in this way… ever. Also, I don’t think fidget spinners make good Christmas presents.

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Holy Diver

With Halloween coming soon, I though about posting a wearable game that my classmate Sam and I made some time ago. It is called Holy Diver.

The principle is that a demon is throwing fireballs at you, while you can catch them and throw it back at it, or defend yourself by joining your palms. However, if you get hit thrice, it is game over!

The game is very small, and it’s prototype can be downloaded here.

The game ran on unity. Well, the song Holy Diver by Dio was meant to be played in the back while playing the game, hence the logo on the costume. It was one of the first time I used a laser cutter on fabric. Laser cutters can be handy in making burned effects on clothes. A costume was made for the game, using Adafruit flora.

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Intuition in Kids

Some time ago, we were testing a STEM related product for kids at a low income school. The purpose of this project was to find out if kids could program using block programming. Another interest was to see how intuitive it was to use a plug and play hardware without much intervention.

The kids really did a good job at expressing their creativity by making fun projects! Due to the success, a newer version of the prototype was developed.

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Water-jet cutting

Water-jet machines are a special class of CNCs which use highly pressurized jets of a mixture of water and powdered abrasive, such as garnet. This can be assumed to be similar to Laser Cutters. They can only cut objects in 2 dimensions. However, unlike a laser cutter, the water-jet can cut through thick metals like steel, aluminum, and even carbon nano-fiber sheets!

Here is an example of a circular disc I cut from a steel slab for a funny little project, which uses the delrin from a previous post.

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Here is another example of water-jet cutting to make a keychain.

Engraving Tools

Engraving on metallic surface doesn’t necessarily need an engraving tool. Depending upon the kind of application, the type of tool can be different. For example, when milling PCBs, a engraving tool can be substituted for a flat end mill tool for better accuracy when it comes to having very minute spaces between tracks, pads or holes.

It is not just the size of the tool that matters, but also the type of the tool used. In a previous post, I had used an engraving tool. Here is just an example of how different it looks when a different tool is used to engrave on a aluminum surface. I used a ball end mill, which is used to give effects of curving or filleting on the edges of the object. Spoiler alert: it did not turn out as I wanted it to.

Check out the video; the process is short and quick.

Making Printed Circuit Boards the old way

Printed circuit boards (PCB) are used in every electronic device.  The PCBs, before they show the circuit itself on the board, they contain a layer of copper deposited on them. This is later removed – etched, to be exact – in the unwanted areas, and become the “connecting wires” within  the electronic circuit. These days, milling machines are used to remove the copper accurately so that human errors are minimal.

Of course, if the design itself is flawed, no machine can compensate for that kind of human error.

Before milling machines were invented or, before it was affordable to use milling machines for PCB etching, the process was done using chemicals. It is still done in that way, but not extensively, as the process has a tendency to remove all of the copper if not done carefully.

The video below shows the simplest way to etch a PCB using household Muriatic acid, ferric chloride, and a clothes iron.

 

Milling cylindrical objects

So, as previously shown, wood is an excellent material to machine into the desired form. It is possible to mill shapes using the tools of tiny sizes. In this case, a 1/32nd in. endmill. You simply need to be careful about the length of the flute of the tool.

Fusion 360 has a text feature in the model section. By selecting the desired font size, not too small for the endmill tool, and choosing the contour milling in the 2D section, it is possible to make appropriate alpha-numeric shapes onto almost any right kind of piece of material.

Ideally, I would have milled an actual cylindrical piece of object, but i found this weird wooden, plain looking keychain. Just so you know, the shape of the wooden part of the keychain is almost cylindrical. So it is better to select a cylindrical stock to make the CAM file.

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Another reason why I milled this keychain was because we used to have an incredibly boring acrylic keychain, badly cut using a laser cutter (and not the one I had milled a while ago).

I’m really glad that I was able to fit the logo and all the letters on the keychain!

Project Spark: Electronics Everyday

This was a bit advanced than the previous workshop. The kids used an integrated circuit, the 555 timer. They learnt to operate it in both monostable and astable mode. In the monostable mode, a push button was used to turn an LED on, where as in astable mode, the circuit operated on its own.

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Further more, some of them modified the astable circuit to alternatively blink two LEDs. A short video summary of the workshop is below:

Project Spark: Fun Electronics

So, the second Project Spark workshop was on basic electronics. It was conducted on January 21st 2018. The kids learnt things such as Ohm’s law and it’s application in building simple circuits.

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They also learnt about special types of resistors, such as light dependent resistor and potentiometer, and also about the bipolar junction transistor. They built a circuit to control the brightness of LEDs using these elements.

 

Delrin

Although, it sounds like someone’s name, Delrin is actually the name of a plastic brand. The plastic itself is called polyoxymethylene, which happens to be a thermoplastic. It is relatively soft when you compare with metals and wood, however, tougher than ABS, making it an excellent machining material. Ever seen a  white colored gear? It is made of delrin. The plastic can also be used to make other objects like handles, guitar plectrums, toys, machine parts etc.

I was working on a CNC based project, and has to mill parts for the final product. In this post, there are only two milled caps. I will make another post on the giant flower-shaped hole in the middle, and the completed project in the future. So, for now, there is this video with royalty free YouTube music and some background noise. The video below shows the milling of delrin, using the circular milling method.