12. Mechanical Machine Design¶
Weekly Assignment:¶
Group assignment:
- Design a machine that includes mechanism + actuation + automation + application
- Build the mechanical parts and operate it manually
- Document the group project
Individual assignment:
- Document your individual contribution
Wire Bender Machine¶
You can find the full documentation for our machine here
Our group — Angel Fang, Noah Smith, Kathryn Wu, and Jenna Chebaro — designed and built a machine capable of bending wire into custom shapes. Mr. Dubick proposed the idea, noting that having a machine in our lab capable of bending wire would be both a practical and engaging addition to our lab.
Our machine is most directly inspired by the wire bending machine by the youtube channel how to mechatronics, but we also used a lot of googling, AI prompts such as this, and a group project of our lab from last year, where they used a very similar mechanism for our feeder.
We have a slide for our project.
Individual Contribution¶
Z-Axis Gears - Kathryn¶
In designing the gears, there was a really nice feature that Angel found. Under Utilities -> Add-Ins -> Scripts and Add-Ins -> Spur Gears, there is a window where you can input the metrics for the gear that you want and it can be automatically made.
I used the following settings for the smaller z-axis gear. The larger one will have the same module but differing thickness, teeth number, and diameter.
Noah let me know that the ideal dimensions to get a gear tight on a stepper motor was a hole with a diamter of 5.25 mm and the line that makes it a D-shape being 0.75 mm long.
I extruded a cylinder around the hole as well, because it would give more strength to the hole so that it does not get worn down easily.
Large¶
For the larger Z-axis, I used the add-in to make the gear then designed an addition to it so that it could be secured on the tube.
Bender and Servo Mount¶
To design the bender and servo mount I find made the gear that it is added onto. I stayed close to the measurements of the original tutorial's design, other than changing the design of the hole in the center to accomodate the bearings we have in the Lab.
Structural Design and Assembly - Kathryn¶
Frame¶
The design of the frame is also largely based off of the How To Mechatronics design. However, a few changes we made include lowering the height and length of the frame, which made it more compact. We found that there was a lot of unnecessary extra space below the wire bending mechanism considering we only needed to make sure it could turn all the way. Because the mechanism we chose to use was also partially different from their design, it did not need to be as long.
This was the first iteration of the base design. We used 0.25 inch plywood.
Originally, we were concerned about whether 0.25 inch plywood would be able to hold the weight of our machine. After this test frame, we decided that it would be fine and we would not need to use 0.5 inch instead. For our final base design, we needed a slit for one of the larger gears, the one that allows the wire bending mechanism to be turned.
This is a sketch of measurements for the final design.
Here it has been printed out, secured using wood glue, and with the components placed to see if they fit properly, which they do.
Ultimately, the components would be secured using screws drilled into the wood.
Wire Bender¶
The wire bender section included the servo motor that controlled a tube that moves up and down and a stepper motor that controls how the wire bends after being fed through. Below is the servo mount and big gear and the smaller gear.
Because we want the wire bending mechanism to be able to turn around, there needed to be a seperate piece that was nota attached to the larger frame. Here is the sketch of measurements for that piece.
The first version I prined out of that design was rectangular, which I quickly realized would not work when the gear was not able to turn to the extent it should. I realized it was because of the design of the gear, how there was a portion underneath that would get caught in the corner of the rectangular design. To accomodate for that, I rounded the corners of the design in hopes it would be enough for the gear to turn all the way.
However, it was not enough and I needed to carve even more out. This was the design that ultimately worked.
This is the gear mechanism working and turning according to code.
Assembly¶
As Noah mentioned previously, there were a few quick fixes we turned to for assembly the night before. One of the main lifesavers was epoxy. Below is how the turning mechanism should operate.
However, it was to be expected that when there was something much heavier on the end, the weight would overcome the friction the gear and bearing had on the long tube. It ended up like this.
We were considering adding wider tubes over our long tube to secure the seperate pieces that constitute it, but we were worried that, too, would not be enough. What we ended up going with was epoxy. We used it to connect the smaller tubes and used it in tandem with the wider tubes to make sure seperate parts would not bend.
This method worked and the end was able to turn based on the gear mechansim.
Then there was also the feeder section. We realized that it was best to feed the wire through when it was straight. When it was not, it turned out something like this.
We also faced an issue where the wire would get caught and slide off from the center of the two gears and this led to it eventually not feeding through.