A Machine¶
A Machine is multi-functional machine that can be used as a pen plotter machine or vinyl cutting machine simply by changing the tool head, the design is made so that the machine can be portable and easy to tweak.
Objective¶
We were assigned on a project called “A Machine”, the idea behind the project is to design a machine that is:
1-Reliable
2-Portable
3-Low cost
4-Can achieve multiple functions
The targeted consumers are students.
Our initial idea was to design a Lathe machine, which grew from that into a broader and multi propose machine that can be used for different operations, simply by changing the tool head.
Electronics¶
For the main board we have to use a microcontroller compatible with grbl firmware which is an open source software for motion control of CNC machines.
we used an arduino uno and grbl shield.
for more details about the software and electronics check Sami website here.
Prototyping Using Design thinking¶
We began our research with the design thinking cycle in our minds, which is method of prototyping that helped us organize our work into a more productive and efficient manner.
Design thinking is multistep cycle, this is how we applied this design methodology in our project:
Empathize¶
In this step, the key is to understand the problem statement and try to research and find as many information as possible from the end user.
How do they envision the product? What makes them excited?
These questions should be answered by the students that the product is designed for, but in our case we could not do a survey of this kind.
Define¶
What features do they want? What safety features do they need?
We thought about what could be suitable for students in terms of functions and what safety features should we add.
We needed a safe machine that minimizes injury if anyone operated it and at the same time we wanted a machine that is capable of performing multiple tasks.
Ideate¶
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For the safety, we thought about a camera detection system that warns the user when someone’s hand is in the area of the machine, to prevent children from any injury.
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In terms of the main function of the machine, we first thought about building a turning machine (lathe machine), and we prototyped this idea but we changed the main function to be broader that just a lathe machine, the machine will be capable of performing tasks such as a pen plotter machine, vinyl cutter machine and possibly a laser cutting machine or a milling machine if we simply change the tool.
Prototype¶
First prototype¶
Our first prototype was a lathe machine, we assembled the prototype in two days to present it and test and evaluate its functionality and to evaluate the idea in general.
hand detection using mediapipe
We used the VEX robotics set to assemble the whole prototype.
Test¶
When we tested our first prototype, we realized that the structure is too rigid and with minimum room for tweaks, so instead of building on that, we decided to use a square shaped structure with x, y and z coordinates.
Repeat¶
Second prototype¶
- Brainstorming
Considering the problem statement, we focused on reliability and the ability to achieve multiple functions, so we started to brainstorm some ideas on how to improve our initial prototype.
In terms of the reliability, we started thinking about mechanisms for the x, z and y-axis:
1- X-axis (Belt and pully system): Using aluminum extrusion for the frame and track rollers for the rotary part and it is attached to a mount (Tool holder). The mount is connected with a belt and two pullies connected to a motor for the driving mechanism. The whole extrusion is connected with the y-axis using a mount and track rollers.
2- Y-axis (Belt and pully system): The y-axis consists of an aluminum extrusion the is connected with a belt the pully system for the driving mechanism, similar to the x-axis.
3- Z-axis (Rods and coupler): The z-axis is mounted on the x-axis, it operates by using a threaded rod and cupper attached to a motor.
And we thought about operating the machine as both a lathe machine and milling machine, using a rotating chuck, the mount on the x-axis can operate as a turning cutting tool.
Using the z-axis, we can operate a milling process by changing the tool.
- Final decision
In the end, we decided to use aluminum extrusions for the structure of the machine, but we faced a constraint regarding the movement of the axis.
We needed to build a movement mechanism with materials that are locally available, so we decided to use the laser cutting machine to cut a rack and pinion mechanism to drive the axis with wheels to move the mount.
We have designed the rack and pinion using Fusion 360
For the pinion (spur gear):
The spur gear has 24 teeth
For the rack:
This is the tutorial that we have followed
We also designed a mount for the stepper motor and the wheels
Use these dimensions to create a 2D sketch then extrude it
We used a 6mm sheet of acrylic to cut the mount and the rack and pinion
A video of Osama cutting a large sheet of Acrylic before cutting it using the laser cutter.
To make the y axis stage stand and carry the weight of the x axis stage, we designed a stand and a base structure to not only hold the y axis, but the machine itself
Stand:
We cut the stand using 6mm acrylic using the laser cutting machine
Base:
Create 2D sketch with these dimensions then extrude it
We cut the base using MDF wood on the CNC milling machine
Manual movement of the x and y axis
Rack and Pinion movement
Electronic movement of the x and y axis
For the z axis, we attached a servo motor with zip ties and double sided tape and a pen, the pen is temporarily fixed on the stand with a double sided tape, as it will not need a strong structure to hold it.
First test as a pen plotter machine
Final Look¶
The machine in action, drawing the FAB LAB logo
You can see the servo motor clicking on the pen when it wants to draw
- The results
- The final look of the machine
