I had some issues posting (my house internet went out) and then senior design pulled me away for two days, so I’m posting a little late. Sorry!
My project is done…ish. Everything is machined and assembled, but the motor doesn’t work. The issue lies within the timing system. Basically, I tried to cut corners to make the machining easier and did away with the conventional system. I now know why there is a conventional system as my timing system is binding up and not letting the motor rotate. Therefore, I’m not even able to test it with air as there is too much friction within the system. I know the solution to the problem, but it requires a complete redesign of the timing system and the main case, something which I do not have time for at this point.
While this is discouraging, I think the motor looks really nice and this is an aesthetics class after all. I have also learned more than I thought I would about designing for manufacturability and actually using the shop tools which were two of my goals. So even though my project doesn’t work in the way I would have liked it to, not all is lost. I also think I have picked up a new hobby. One day, once I have settled, I would like to put together a small garage shop and build little engines like these. This way I would be able to really put in the time they deserve. All told, I’ve put close to 200 hours into this project and the machinist in the shop, Cameron, has put countless hours into it as well through programming, manufacturing, and helping me. While this is a lot of time, examples I have seen that work smoothly require close to 1000hrs of machining. I think throughout a year in a home shop, I would be able to produce a working engine.
Here are some pictures of the engine in its current state:
Wow, this looks very cool! Can’t wait to see it on the EXPO
Looks really good. I like the stand too. Have you tried putting a crank on it, and maybe easing off on the valve springs or whatever?
I’m not quite sure what you mean by putting a crank on it, but I did try to spin it with the flywheel (not pictured) attached and it broke the plastic connector (designed to break before the aluminum). It does spin freely with all of the springs pulled up, but they have to be in their exact position or the air/exhaust will be mistimed.
I am very impressed by this project. Although it doesn’t function as you originally hoped, the aesthetic value that it holds is just as satisfying as the mechanical purpose it was supposed to have. The machining you performed for this project really seems to have paid off, and this project will make a perfect addition to your future engineering office. I am really excited to take a look at this engine at the expo.
This is absolutely amazing. I would gladly buy one of these if you started a little side business. I’m bummed the timing system got messed up but I think if you have time this summer it would be well worth it to try and get it fixed. Regardless, as you mentioned, this is an aesthetics class and I think you knocked it out of the park on this project. I love the look of the engine and especially the way it sits on the stand. This is by far one of the coolest projects I’ve seen so far. Awesome work.
This is an amazing project and every time I see you in the shop I get really jealous of how proud you should be for creating this! What are the ways that you cut corners during machining? I would be interested to learn more about this for future project that I might work on.
I think that it is great that you had the goal of learning more about DFM (design for manufacturability) through this project. This curiosity and desire to learn will serve you well after graduating!
The main place I cut corners was in the timing system. The proper way would be to have a hinged pushrod and a planetary gearset. These are all off-the-shelf parts, but not at this scale. The thought of machining the sun gear and .25in tall hinges gave me nightmares. That’s why I decided to go with the internal springs (where the problems started) and the helical cam.