This is a simple piston ring expander tool. It is designed for compression rings for pistons that are 98mm (3.85in), but I think it would work well on compression rings for a piston that is 85mm to 105mm (3.85 +/- 0.5 in)

The specific intended engine is the AMC/Jeep 4.0L straight 6. I think the pistons are the same size in the AMC/Jeep 2.5L straight 4, but I'm not positive.

There are four parts that snap together. The retaining ridge on each joint is significant, so you might have to tap the pieces with something (small hammer) to snap the pieces together.

Two of the small end pieces are required. (Avoid the temptation to mirror them. The required ends are identical -- not mirrored.)

Supports are required, but only for a limited part of the print. Please see the notes under "Print Settings"

Prusa

i3 MK2.5

No

Yes

0.2mm layers, 0.4mm nozzle

50% (not critical)

The model requires supports, but only for the grooves in the end pieces where the ring sits.

If you set the overhang threshold for 30-deg or less (where zero is horizontal), then that should cause supports to only be created in the needed area.

There are four parts that snap together. The retaining ridge on each joint is significant, so you might have to tap the pieces with something (small hammer) to snap the pieces together.