Not Bad for a College Student

[TheycallmetheTIG]

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 maintenance. I made several major improvements, such as all milled mating surfaces, much larger flywheel, heavier base, removeable crank, and a bunch of others. It has a .40 inch bore, a 1 inch stroke, and will run down to 15ish PSI input or less (the gauge reads zero when I got it running really slow). Soon I want to make a more advanced engine with a true valve setup and a steel piston and cylinder. If you all see anything I can improve on let me know!

 

[minh-thanh]

Great run, Congratulations!
Improvement : I don't know , but if ... make it more beautiful , wooden base , paint engine color .

If you don't know ..The table below is the material combination for the cylinder and piston

 

[TheycallmetheTIG]

Great run, Congratulations!
Improvement : I don't know , but if ... make it more beautiful , wooden base , paint engine color .

If you don't know ..The table below is the material combination for the cylinder and piston

View attachment 137563

Thank you very much for the chart! I have been trying to figure out what materials I needed to go to on my next engine for weeks. I knew I had messed up when I went from a perfect fit to 10-20 thou of slop between the piston and cylinder in a matter of days. This chart backs it up. I am surprised to see such a difference between the Drill rod, and the other steels. Is this because of the hardness? If so, would hardening a lesser grade steel make it last longer? I do still have some cleaning up to do, such as that ugly weld on the front, and I am going to add an exhaust stack, but I think I am about to set this one aside and begin another.

 

[minh-thanh]

I am surprised to see such a difference between the Drill rod, and the other steels. Is this because of the hardness? If so, would hardening a lesser grade steel make it last longer?

That's a question I can't answer, because - simply - I haven't done it or tried it yet
Hope someone will have an answer for you
With Drill rod + steel : I have used it in my diesel engine oil pumps - the results are great.
If you want , you can try , sometimes you will learn something
( I've incorporated aluminum cylinders and pistons in the stirling engine - with cylinder diameters of 6, 8, and 10 mm, and the engine still runs. )

 

[TheycallmetheTIG]

That's a question I can't answer, because - simply - I haven't done it or tried it yet

sounds like a test of some sort is in order... I should just stick to the chart for now, the drill rod piston in an aluminum bore is just too easy. Perhaps a drill rod sleeve in a aluminum block with a brass or aluminum piston? No matter what I come up with it has to be better than what I got!

 

[minh-thanh]

Hi !
Never mind the Drill rod. Unless you want to make an oil pump for a diesel engine and you need it to be really good.
The combination as shown in the chart ( G or E ) is enough good for all engines that you will do .

 

[gbritnell]

Nice first job! Welcome to the fraternity.

 

[Steamchick]

Hi TIG, good to see the engine running. You mentioned a "lack of balancing" in another thread. Well, everything can be balanced, but it is really complex and needs a couple of auxiliary shafts as counterbalances to get a true balance, In your case, I would simply take a small lead weight, or coin, or something, and have a try with some plasticine or dough or something just to hold it on to the rim of the flywheel in various positions. Opposite the crank is the first to try. With the spring pressure slackened to almost nothing, just give the flywheel a gentle spin (to break the static friction) so it stops after a few turns. You should get repeatability of the position of the crank if well out of balance. Have a play and enjoy the model - You can learn a lot from this one.
K2