The first part of machine building is designing one. And to design one, I need to know what and how to design. To I first tried to understand what machines are and how to design them. Machines are of various types and depending upon their use and their movement(axial and rotational). To name and explain a few types are cartesian motion, six-axis, 5-axis etc. To explain the same in robot context here are few examples.

SCARA Robots

SCARAIndustrial robots are defined as ‘multi-functional manipulators designed to move parts through various programmed motions'. As such, robots provide consistent reliable performance, repetitive accuracy and are able to handle heavy workloads and perform in harsh environments. Additionally, robots can be quickly reprogrammed to reflect changes in production needs and cycles.

The SCARA acronym stands for Selective Compliance Assembly Robot Arm or Selective Compliance Articulated Robot Arm Robot

The machine we are going to use is of Cartesian motion type. The movement of the axis is better explained in MTM by Nadya and James through these beautiful illustrations.

So since this is the first time with machine design decision to keep things simple and doable. A lot of mechanical parts and electronics involved. As a group, we decided to do an X-Y plotter machine.

Designing

 The prototyping started with MTM kit. I downloaded the files from the site

And modified it in cad to suit our material needs and arranged it in a way to save space and material.

The next part was cutting and assembling them.

I assembled the millboard cut parts. Once we assembled and checked the working of the parts we wanted to redesign the machine. The idea was to make the machine in a minimalistic way and also to combine the X and Y axis of the machine. This was anyone can make this machine at low cost and with an easy manufacturing process.

While having this idea in mind is when we came across a design in Thingiverse.

So having taken that design we decided to go with laser cut parts and less of 3d printed parts, as this would be faster to make and prototype. So having some of the key elements of the design as it is, certain parts we decided to do it in MDF through laser cutting process. I was in charge of doing the designing.

2D Design

I used AutoCAD to design the machine. I've been using Autocad for quite some time so I'm really comfortable with it. It is like a pen tool for me. The tricky part was to first draw the base and exact locations of the bearings and its centers because the rod locations have to be measured to fit incorrectly.

I drew the base of first measuring all the dimensions from the physical model and also the 3d model in Meshmixer. Once the base was ready drew a basic elevation and sections of the model. The design needed a lot of refining and it was very boxy, but for a prototype, I first need to know if all the dimensions were right.

So we laser cut this model and tried assembling it. The dimension was okay, but I had not made it press fit type. Since the fixture dimensions were fine I just had to design the notches for press-fit and also the Y-axis parts.

A lot of iterations went on again this time, this is because the belt wasn't aligned to the motor. So made a small stage where the motor could sit and below, the Arduino and can be concealed.

After this, we knew how the machine works, its stability. So all the problems were identified and after much iterations, this is the final design of the x-axis.

Now that the model was ready it was time to make the base. Where the model can be fit in. I started measuring the base manually. This gave the exact dimension that I have to consider.

Once I had the measurements, I made a rough model in Sketchup to understand exactly how the model is placed, this helped me do the 2d file for the same.

What happens is the model gets mirrored twice. I wouldn't have been able to get that right if I had done the model. The next is to laser cut the base.

Once all the model and laser cutting was done, I used spray paint to paint the MDF models.

Gave the model a coat of Lacquer and matt black paint. And then assembled the model on to the base.

The next part was to put all the components together.

I was also in charge of documentation of the group page which included the documentation of the assembly of the machine, editing videos and creating the introductory slide for the presentation. The after documentation I had composed the page for the group site as well.

 Creating the slide was a bit of a challenge as I wanted to make it aesthetically pleasing, but also informative, explaining the entire machine in a very simple way. The slide can be divided into 3 parts where first I explained the process of making the machine, the materials required and the additive / subtractive process involved. The second part is the 3d model of the machine, This would give the viewer a basic idea of the machine and the third part is the parts of the machine and their actual photos.

To edit the videos I used movavi video editor software. The software can be downloaded from here:

The idea was simple. to explain the process as it was done and using necessary videos and pictures to illustrate the same.

These were my individual contributions for machine design week. Apart from this the whole group was involved in prototyping, assembling and testing the machine.