Wobbler Engine

By Cole Rutkowski

Background:

               In the Fall of 2024, I landed a job as a machine shop assistant for the MCEN1025 class at CU, a freshman-level engineering class focused on introducing CAD modeling, engineering drawings, geometric dimensioning and tolerancing, and manufacturing methods to students. The most intensive project in the class is to model an air-powered wobbler engine, create thorough engineering drawings, then manufacture and assemble the parts. The metric each group must achieve is an engine that operates at an air pressure of 10psi or less; the best engines typically run at a pressure of 1-3 psi. On the last day of class, the students compete in an engine runoff and crown a winner for the most efficient engine.

               In my role as a shop assistant, I guide the students through the machining of their parts and teach them safe operation of our machines. Most of the students have never stepped foot in a shop, much less seen the machines we use. In the span of five 2-hour timeslots, the students learn how to safely operate our mills, lathes, drill presses, and bandsaws; how to use tools such as chucks, collets, edgefinders, drills, endmills, and reamers; and how read an engineering drawing and determine a sufficient order of operations to manufacture the part.

               Having worked with the students all Fall, I was keen on making my own engine. In my spare time, I went in to the shop to make each part again, but this time for myself. Afterwards, I decided to recreate the models and drawings based off of my knowledge and memory of the drawings the students used in the shop.

Results:

               After manufacturing and assembling my engine, I was ready to put it to the test, head-to-head with the students I worked with all semester. On the day of the runoff, I was able to compete in a special student-vs-assistant competition after the student winners were crowned. In my race, I was put up against the 5 best engines, ultimately finishing the run-off in 2^nd, behind the overall winner of the student competition. Out of 100 students, I was very happy to place 2^nd and even more impressed with the quality of the winning team. The top 5 groups all ran at 3 psi, and I was able to hit 2 psi before sputtering out, but the winning engine was still chugging along at 1 psi!

               In my role as a shop assistant, I expanded my knowledge of the shop and my skills with the machines. The repitition of making the same parts several times refined my efficiency and knowledge of manufacturing with lathes and mills and reading engineering drawings, and my role as a teacher strengthed my confidence and gave me a stronger understanding of the manufacturing processes. I also freshened my CAD modeling skills when I revisted the design part of the project myself. Above, you can find the drawings and model of the engine.