Making a graphite piston

[Chuck in E. TN]

 I'm making a replacement piston for my non-running attempt at a Poppin Fire Eater Engine. First time I've worked with graphite, and boy is that stuff soft! That brought up a question. How do I attach the piston to the piston rod? Will this material take threading? Do I need to add a nut on the head end, or sandwich it between 2 nuts and washers? What do those of you that have made graphite pistons do?
 Chuck

[vtsteam]

I kept mine solid and slotted the end with a mill to a sliding fit to accept a flat conrod.

The wrist pin was 1/8" brazing rod. Drilled a hole perpendicular to the slot, and insert the pin through the piston and conrod.

I grooved the outside of the piston for 3 light vee grooves.

Cylinder should be bored and lapped first before fitting the slightly oversized piston. Plain paper can act as very fine sandpaper to "lap" the piston down in the lathe to just fit the cylinder bore. When tested with a thumb over the end of the cylinder the free piston should take a minute to slide down under its own weight for a good seal. Hope that helps!