Introduction: 

For the Final Project of the semester, we were instructed, in teams of two to four, to 

design and manufacture something that could move in the x, y, and z axes using two stepper motors and a servo motor or a solenoid. The x, y, and z axes were also limited to moving 2.5 inches in each direction. When coming up with ideas, my teammates and I decided on creating a CNC Braille Engraver. This project works similarly to a CNC machine but with a few twists. Instead of simply using a drill bit, an electrically powered engraving pen with multiple levels of speed was used. Our engraving machine also specifically engraved the braille alphabet to create “learning guides'' to aid those who are learning braille. By engraving the alphabet, it helps the individual familiarize themselves with the texture of each letter.

 

Conceptual Design:

Sketches were made to illustrate the conceptual design. Essentially, the machine was constructed with multiple 8020 aluminum extrusions. The stepper motors were connected to the extrusions. The extrusions were screwed into a wooden board where the engraving material was placed. The middle bar was attached to a plate which moved in the x direction but also held a servo motor which moved the engraving pen in the z direction.

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                                                                            Conceptual Design Sketches

Linear Stage:

Before considering all three axes, we had to first demonstrate that we were able to 

create movement in the x and y direction. To accomplish this, we decided to use a belt pulley system where a motor was attached to a timer pulley which rotated a belt. The belt was attached to a slider, which moved back and forth. To incorporate this, CAD-ed components using Solidworks and then 3D printed them using PLA. These components were then fastened onto the extrusion. One of my teammates designed and 3D printed a slider plate that was attached to v wheels. The belt connected to the plate, while the wheels slid smoothly on the aluminum extrusion. For this part of the project, I was mainly responsible for designing a pin holder that would hold the idler pulley and be fastened to one end of the aluminum extrusion. Gcode was inputted in the motor using Repetier Host to allow for the plate to move back and forth. This process was later repeated for the y axis.

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Pin holder design on Solidworks

 

Z-axis design:

After the Linear Stage was complete, it was time to design the z-axis. For the z-axis, a 

a servo motor was used. Through CAD design, a gear and rack for the servo was designed. The purpose of this was to create a rack pinion mechanism where the rotation of the gear by the servo caused the rack to move in a downwards motion. The rack was directly attached to the engraving pen, allowing the pen to slide downwards and upwards when necessary. 

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Rack/Engraving Pen Holder on Solidworks

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Putting it altogether:

After finalizing the three axes, it was time to put it all together. The aluminum extrusions were all fastened together. Fastened to it were motor holders and pin holders, which held the belt and slider plates. 

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Photos of Assembly

 

Code:

When it came to the code, as mentioned previously, Gcode was used to drive the motion of our motors using a software called Repetier Host and a MKS Controller Board. A Gcode script was written to instruct the motors to move the pen down to the material, engrave a letter of the braille alphabet, move the pen upwards and to the left, and repeat. Due to the distance constraints posed by the project, we decided to only engrave the letters “A”, “B”, and C”. 

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Gcode Script used on Repetier Host

 

 

 

Finally, after assembling and troubleshooting a bunch, our product was able to work!

 

 

 

 

 

 

 

 

 

 

 

 

 

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Demonstration Video of CNC Braille Engraver

Lessons Learned:

It is a bit cliche to say it, but many lessons were learned in this particular project. When it came to the engineering side of it, I learned a lot about designing parts that will actually fit. Such was the case when I had to make holes and fittings in my design. When manufacturing it, I learned to properly adjust a drill press, use a saw, and tap holes. I also gained a deeper understanding on how Gcode worked to move something. When it came to teamwork, I learned the importance of planning ahead, managing your time wisely, and updating each other whenever necessary.