piston oil grooves

[John galloParticipant @johngallo38006]

Hi, I'm building the Stuart D10 and I have a question on the pistons. The plans call for 3 oil grooves equally spaced. They do not specify the shape or size of them. Rather than taking a guess on some thing I know little about, I was hoping some one may have done this before or can make an educated guess as to what these grooves should look like.

I also read that a single 1/8" groove packed with graphite yarn could be used. Might this be superior to the grooves? The piston is brass while the cylinder is cast iron, if that helps.

Thanks in advance, John.

[John galloParticipant @johngallo38006]

[JasonBModerator @jasonb]

If you use a Vee tool and go in about 0.010" that should be fine on a small piston like that. A 60deg threading tool will work OK or you can grind up your own quiet easily.

A lot depends on what you want to do with the finished engine, if you are just going to runit on air or low steam pressure for display then the grooves will be more than adequate. If you intend it to do real work then a groove an packing will be better, an O ring is another option too.

[Neil WyattModerator @neilwyatt]

I used a silicone o-ring on my 10V.

Neil

[Ian S CParticipant @iansc]

For my hot air engines I use Labyrninth grooved pistons of similar dimentions to those suggested by Jason, mostly not quite the .010" depth as I try to get the piston skirt to about .040"/1 mm thick.

Ian S C

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