Hi Rin,
Schooling is definitely different in Hungary, students here in the UK won't be back at their desks for another week. From what I remember there are a number of straight forward oscillating engines in Elmer's drawings. I have not made any of his engines however, if you haven't looked already looked in
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there is often a build thread of Elmer's engines and you might get answers from someone who has built what you are considering. Just had a look on the site and found this
Hello, this is my first engine. I designed it based on a concept that is widely used at my school for a class project, but I really tried to push the envelope on machining precision and ease of mai...
not an Elmer but could prove useful.
Good luck with your project.
Take care Tony.