Engine parts (cylinder, piston, orings)

AssassinXCV said:

What is the difference between delrin and UHMW other than the price and the possible lower coefficient of friction? Is delrin stronger? Piston is 1/2" diameter with similar connecting rod cut out that you posted. Also, even though delrin is smooth sliding would it still be best to use some sort of oil or WD40? One thing though in my first piston I made out of aluminum, the drill bit i used created a scratched tool marked surface (looks similar to a crosshatch hone) with out reaming, but it feels smooth to the fingers, which I suppose would be good for retaining said oil.

Ian

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Bogstandard said:

Don't over complicate things.

These small air engines you are making will usually last a lifetime as they are not run 24/7, but the odd minute or two every so often.

Unless you go for auto galling fits of say ali against ali, almost any combination will work within reason, so use the cheapest and what you have knocking around to make them out of, even pieces of hardwood can be used as pistons

Enjoying the making and getting them to run is a lot more important than getting aerospace products together that would make them last thousands of years of running non stop.

Old bolts, even bits of metal you pick up in the street, can all most probably be used for making and running these little engines.

Even my old finger engine made out of string, bits of twigs, a tiny bit of ali tube, a wire coathanger and a few screws and superglue still amazes people when they come into my shop for a play.

Use what you have readily available, and enjoy yourself without worrying about compatibility problems.


John

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