Here I have designed and tested a fun project finger engine, test your coordination skills to get it running!
You will need some 3mm steel rod for all of the hinges and crankshaft and small washers to fit the shaft. Americans can use 1/8" rod and drill the holes to suit.
Print 2 crank webs and get them the right way up as there is a slight boss on one end.
Print the 100mm flywheel solid as you need it to be as heavy as possible.
You can if you wish print 2 flywheels and have one on each side, if using 1 flywheel print the pulley for the other side.
Everything else is printed 20% infill PLA, ABS anything will do.
Make sure there is minimum friction it takes a bit of care to get everyhing right. The crankshaft when built up should run true and the pins should be tight. The connecting rod should be drilled for a loose but not sloppy fit.
I will at some point do an assembly video when time permits. please share your build if you build it. Thanks and enjoy. Steve.
Overview and Background
Lesson Plan and Activity
See main text for build notes an assembly video will be published soon.