CNC and Machining, Creative, Engineering

Aluminum Tree

As shown previously, Aluminum is a relatively soft metal, and it can be milled easily. This time, it is  a 4 in. x 4 in. sheet of aluminum. I simply used a previous dxf file created for milling plywood, and reused the same gcode.

The process took only about 30 minuted to mill, and the output was clean, even though I had used a 1/16 in. ball end mill tool. Had I used a smaller sized tool, it would have been much more precise, but it would have definitely taken hours to finish the job.

Here is the time lapse video of the process. There is a bit of engraving at the end, but it is not very satisfying. I will make another one showcasing the engraving soon.

CNC and Machining, Engineering

Circular Milling

Aluminium or Aluminum is a relatively soft metal. It is light, but also durable, making it an excellent material to create useful parts for things used in everyday life. It had been a while since I tried to test different kinds of milling using Autodesk Fusion 360.

Fusion 360 has a really good way to create GCODEs for circular objects. It is similar to contour milling or profiling, but specifically meant to create circular or cylindrical objects with minimal wastage of materials.

I decided to make a couple of aluminum rings. Since a metal was being used to mill another metal, it was very important that the distance between each subsequent each step over was very small. Unfortunately, this meant that the process would create aluminum powder instead of swarf, and I had to be very careful while cleaning the OtherMill once the machining was completed.

Regardless, the finishing was beautiful and it actually did not need any extra polishing.

 

2D designs, Creative

Copal

Laser cutters have lenses which are responsible for focusing the laser onto the surface of the material to be engraved. Unfortunately, someone did not use the Epilog Fusion M2, and broke its lens.

Oddly, the lens is a yellow and has a shiny coating on it. When the lens broke, it looked like a spider trapped inside some kind of a crystal.

It looked like amber, but not fossilized. Copal is a resin from different trees, and just like amber, it can have small insects or objects trapped inside it. However, the difference is that copal is not fossilized, and hence cheaper. I made  a simple design using illustrator so that the clear acrylic only melts instead of getting engraved and leaving a residue after the engraving. I also made vector cut circles, so that I can used nuts and bolts to keep the entire thing within the two pieces of acrylic.

And thus, a “copal” was encased.

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CNC and Machining, Creative

Milling and surface finishing wood

Wood is a beautiful material for milling. It is possible to mill any type of wood because of its relative softness when compared with the milling tools.

This time, I tried working with plywood. The unfortunate thing about working with a desktop CNC machine is the size of the spoilboard. Because of the thickness of the material, it is not possible to mill without using brackets, and this reduces the size of spoilboard significantly.

After laser cutting a 1/4th of an inch thick plywood sheet to a size of 4″x4″, I placed it on the spoilboard with a bracket. However, I did not use any double sided tape to see if the bracket would hold. And yes, it did hold the material in its place without causing trouble. Another reason for not using tape is because I did not want any sticky residue on the wood, as I was planning to mill both sides.

By this time, it is obvious that I’m still continuing to use OtherMill and Autodesk Fusion 360. I decided to get a DXF image of a tree and created a GCODE. The primary difference is the the tool. For the first time, I decided to use a 1/16th of an inch ball end mill tool (I also tried the same with a 1/16th of an inch flat end mill).

The ball end mill gave a better finish than the flat end mill. I have some place plans for this piece of milled wood.

CNC and Machining, Engineering

Can you mill floor?

It depends on what you mean by floor. The floor at one’s home is made of a variety of things: tiles, concrete, granite, marble, limestone, wood,  cork etc. Most of these can actually be milled to create beautiful pieces of artwork. Some of them can also be milled to make useful things.

Take linoleum, for instance. It is made from substances. These generally include solidified linseed oil, solid pine resin, ground cork, finely pulverized wood, and limestone, usually on a  canvas backing. An excellent use of these is to make stamps.

I simply created an SVG file, imported it in Autodesk Fusion 360, and made a CAM gcode file for the OtherMill.

Well, milling is fun. However, milling linoleum is a special case. The dust created from the milling is very much like powder. So it is very difficult to clean the OtherMill after the milling process is complete. This is also the first time I used more than one bit to mill the material, as some of the parts needed a finer milling tool.

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Of course, this stamp is for display purpose only. The actual stamps will always be mirrored so that the text can be read once a paper is stamped.

3D Objects, Creative

3D Printing Springs

Springs are elastic objects made of metals, most times, spring steel. A project that my team was working on needed a spring to create a compression and extension action. 

Unfortunately, when a cylindrical part meant to be used with the spring was designed, it had dimensions larger than the standard spring sizes available. We had already begun printing the cylindrical part, so there was no going back (as we were using a high-end 3D printer). So we decided to print a spring!

The spring design was made using Rhino, as it has a simple function that can make helical shapes and make them into solid pipes. And, if you think about it, a spring, is actually a solid helix shaped pipe.

Printing a spring would mean taking into account for its flexibility. Using regular materials like PLA or ABS will make the spring rigid. So we used a non-standard material which was flexible and strong: Thermoplastic Polyurethane, commonly known as TPU. A completely solid infill print on TPU with support structure will make the spring looks like this when it has finished printing:

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The only annoying thing about using this is the removal of the support material. Otherwise, the print comes out pretty good. It might look a bit messy, but it is good enough to be a low fidelity spring for rapid prototyping. The final prototype kind of reminds me of a slinky 🙂

The black one was a test and the transparent one was the improved version.

For the spring in action, check this video:

3D Objects, CNC and Machining, Creative

A maze of ABS

Acrylonitrile butadiene styrene (ABS) is a widely available thermoplastic. You can usually find them in legos.

While continuing my test of materials on OtherMill, this time, I decided to try ABS. The material is pretty soft, and can be milled easily. Unfortunately I could not find a block of ABS, so I printed one on a Mojo (much to the dismay of many).

I created a design for a Maze on Adobe illustrator, exported it into a DXF file, and extruded it into a 3D model, and made a GCODE file out of it.

Fixturing an object on the OtherMill can become tedious of the surfaces are not flat. Since my block of ABS was printed, it was quite flat and, only using double sided tape and a bracket with some fastners did the trick. The entire milling process took about 29 minutes (OtherPlan has a tendency to lie when it displays the milling time, because it said about 42 minutes).

I only have the video of how the milling ended (because a 30 minutes long video is what we want but not what we need)

Clearly, the machine can be very messy. But that’s why it needs to be closed while using.

Above is the final ABS maze. Below are images of the finished product.

      

CNC and Machining, Creative

More Clear Acrylic – Same things made using two kinds of machines

Got another chance to mill clear acrylic into a few  key chains. This time they are less bluer, but thinner than the previous ones (about 3.175 mm or 0.125 in thick). Milling gives away really clear surfaces rather than burnt ones.

On Laser cutters, the texts are engraved by, again,  burning the surface. The flat end mill can make the surface look more transparent than laser engraving. It is true that milling will make a transparent acrylic surface into translucent. But the finish is cleaner than the laser cut surface.

These images shows that it is not possible to deeply engrave acrylic using a laser cutter, but a CNC machine can do the job just fine! The key-chain on the top is made using the CNC macine, and the other two using the laser cutter.

3D Objects, CNC and Machining, Creative, Engineering

Jansen Linkage

Wouldn’t it be more appropriate to use a laser cutter to cut acrylic rather than using a small desktop CNC (Computer Numeric Control) machine to tediously mill it to a desired shape?

Well, the answer is not obvious to sometime who doesn’t care about having unfinished edges.

The difference becomes more obvious when using transparent acrylic. Using a laser cutter, melts the acrylic, leading to the “cut” sides to look more or less like melted plastic, and opaque. Using a CNC machine, on the other hand, gives it a smooth and nearly transparent (usually it’s translucent). Check the image below and you can see the finish.

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I decided to make a Jansen linkage model using clear acrylic, a piece of cardboard and some 3D printed parts.

I used Autodesk Fusion 360 to design the shapes and linkages, and also create a gcode file thought is CAM component. Finally, I used an OtherMill to mill them using a 1/16 inch flat end mill. The results were spectacular. The milled surfaces were smoother than any any piece of acrylic cut using a laser cutter.

The brown cardboard was etched and cut using a laser cutter. And the silver pins were 3D printed on an Ultimaker, using an STL file created using SolidWorks. The image of the final prototype is below:

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It doesn’t make sense to have a fixed Jansen Linkage model. The whole purpose of having it is to make it look like it is walking. Connecting two or more of these models can make it look like it is walking with more legs.

Here, check it out in the video:

 

Engineering

A project from the past: ARTEMIS

High-altitude balloons are unmanned, filled with light gases (either hydrogen or helium), initially released from ground level. They can be used until they reach the stratosphere. Due to their comparatively low rate-of-ascent, these balloons are perfect candidates for precise measurements of sections of the atmosphere. High-altitude balloon experiments and activities in India are very rare. This project makes use of an alternative use for high altitude balloon. Imagine a situation where an area is struck with a disaster (natural or unnatural). Usually at such times, there are constant telecommunication problems. This is the main drawback of any such systems. A distress signal must be sent to rescue centers and ground stations to receive help. Data from the disaster struck area must be collected and sent for analysis. A possible solution is ARTEMISAirborne Remote Measurement and Information System.

A small box containing electronics, including measurement equipment like sensors and transceivers was attached to a set of 3 large high-altitude balloons (making it airborne). This was tethered to ground to make sure that it wouldn’t fly away. Multiple ground monitoring and control stations were set up to constantly monitor the transmitted data. Data presentation was available in these stations. A Cut-down altitude was set in the ground control station. When the balloon reached the cut-down altitude, i.e. the balloon was detached from its tether, a sub-system known as the Cut-down mechanism (made of heated nichrome wire) would separate the payload from the balloon. The cut-down mechanism was also an emergency Flight Termination Unit (FTU) in case of system faults. A parachute attached to the payload minimized the rate of descent and provided a safe landing. Since the test height was not in thousands of meters, a GPS system for recovery was not necessary. Finally, a recovery team could be dispatched to retrieve the payload. The payload could be serviced and reset for the next flight.

Doing a few tests, we determined that the payload was constrained to 300g. This forced us to use three baloons which could expand upto 3 meters in diameter, filled with hydrogen (since Helium was very expensive). A XBee Pro S2B was used as the communicating device at the airborne system, and at the ground stations. The FTU which  was a nichrome wire, was heated by a sudden surge of current provided through a Li-Po battery. The battery also powered the microcontroller used to control the FTU and Zigbees.

The main advantage of using a high altitude balloon is that it increases the range of communication. For instance, if the range is rated as 2 km line-of-sight on ground, then we observe that the same range increases if we consider one part of the system at an altitude.

Below is the launch sequence of the system:

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