Intro
For the first midterm of ENGI 210, the class was tasked with creating a mechanism that incorporated one movement from the 507 Mechanical Movements given. To complete this project we–Brian Seo and Daniel Plascencia–ended up partnering up to create a sexy pump jack.
The idea for the pump jack arose from Brian’s internship experience and his knowledge of pump jacks, specifically the Mark II model. With an idea in mind and the tools at our disposal to bring it to fruition–we went to work.
Procedure
-Blueprint-
We began our project by drawing out a sketch of our oil pump jack. On our sketch, we first drew up the outline of the pump jack. Next, we drew in the individual parts, connecting each part with circles that represented pins. Looking up mechanical models, we found that the motion that most closely resembled the movement of the pump jack was Mechanical Movement 222 (minus the gears). Once we drew our simple 2-D design, we then began planning on the 3-D layering of each part. By highlighting each part with a color that corresponded to a “layer level” (from top to bottom), we assessed each part to a layer so that the parts would not overlap with each other.
After finishing the layer, we had to decide on the scale of our model. Since we wanted to make the model transportable, we decided to scale the model to be 1’ long and 1’ high. With our dimensions set, we redrew our 2-D sketch into Adobe Illustrator (AI). Finally, we made a separate AI file, and we separated each part as an individual shape so that we would be able to cut out our parts on the laser cutter.
– Low Fidelity –
Now that the initial blueprint sketches to be cut out were ready, we needed to see if the parts were really going to work well with each other to produce the motion we were after. In doing so, we laser-cut-out the pieces from cardboard and put together a rough 2-D model confirming our model’s ability to perform the motion. This gave us the green light to proceed to build the model in 3-D; a model that stands vertically with a base to attach to its members. Furthermore, this low fidelity model was sent to the petroleum engineer Brian had worked with over the summer to glean insight into our design.
– Mid Fidelity –
When we got feedback from the engineer, we were told to lengthen the horsehead (the hammer-shaped part) to make it look more realistic. Furthermore, we realized that we needed to extend the length of the three legs so that the counterweight (the rotating part) would not touch the ground. We began by editing our AI file, increasing the length of the three legs. To create a better support for the entire structure, we also added tabs at the bottom of each leg. We then created a base that had three holes that corresponded to each leg. By attaching the tabs into the holes, we were able to create a more stable, free-standing structure. To not have holes at the bottom of the base, we created another base (without holes) on the AI file; we planned to stack the two bases together.
Once we printed out our second model, we attached all of the parts using wooden dowels as pins, then duct-taped the legs to the base. Once we assembled them, we ran into an immediate problem: the parts kept falling off of the dowels. We knew that we could not glue the parts to the dowels since then the parts would not be able to rotate on the dowels. To solve this problem, we decided to use rubber bands; this allowed us to secure the parts from falling off the dowels without stopping the dowels’ rotation. One we attached the rubber bands, we decided to improve the stability of the legs by attaching two dowels on each leg. This allowed the structure to not fall on a side due to its asymmetrical shape.
– High Fidelity –
With all the new realizations and improvements made from creating the mid fidelity model, we were finally ready to create the high fidelity model. This was a one to one recreation of the mid fidelity model with the addition of using higher fidelity materials and post-processing. So, we laser cut most of the parts out of plywood, plasma cut the middle leg out of steel, and cut the peg supports out of 1” diameter dowels. As for the pins, we used the thin dowels available to us at the OEDK and rubber bands to hold them in place.
Once the materials were gathered, post processing took place. We began by sanding our wooden pieces to give them a smooth finish. Starting with lower, harsher grit sandpaper and moving onto fine, smoother grit sandpaper. A similar process was done for the metal leg; however, instead of sandpaper, sandblasting was used.
With all materials having uniform textures, it was now time to paint. The wooden members of the oil rig got stained with classic black (two coats applied). Followed by powder coating the metal leg red, and finally spray painting the support pegs, pins, and base gray.
Assemble the finished pieces together and…voila!
Reflection
– Brian –
Throughout the project, I was able to expand on my knowledge with tools at the OEDK and my critical thinking skills. This came in handy especially when we ran into unexpected problems. For instance, due to the vast demand for the laser cutter, there would often be long queue lines, and people would often use the laser cutter for over 2 hours per session. This made the laser cutter unavailable for us during our high-fidelity stage. To overcome this hurdle, I went to the Moody Makerspace to cut the high-fidelity plywood parts. Although the laser cutter at the Moody Makerspace operated on a different program, I was able to utilize the laser cutting knowledge I learned from the OEDK to easily learn how to use the laser cutter at Moody.
Another unexpected hurdle we faced was when our pump jack could not turn. This was because the wooden parts would rub against each other, creating enough friction to stick the parts together. To combat this, we initially planned on cutting out steel washers by using the plasma cutter. However, we then realized that it would be much easier to just use the metal washers supplied at the OEDK. This ultimately saved us a large chunk of time on plasma cutting and postprocessing, and it smoothened the movement of our pump jack.
– Daniel –
This project was fun to complete. There were times when I would do work and get lost in the flow of creating. It was a great space to be in and it taught me the ability to think on the spot when problems arose. This ability to pivot was helpful in maintaining consistent progression of the project and minimized hiccups along the way. Not only do I feel like I got useful experience in this area, but my communication and delegation skills were reinforced by working with Brian. We were able to work as a duo and contribute to a project we both were very proud of in the end. I believe insight to these intrapersonal skills were more important than the practical skills I was able to improve. Although, getting more comfortable with the laser cutter, and powder coating are a definite plus!
Cost
Materials:
- Wood: $50
- Dowels: $1
- Steel: $7
- Spray Paints: $5
- Wood Stainer: $10
Labor:
- 12 hrs x ($7.25/hr x 2) = $174
Overhead: (plasma, laser cutter + powder coater + sandblaster + etc…)
- $110
Total Cost: $357
