Many of us have been frustrated to discover that the pins for emmett's Screwless Heart Gears are not PLA compatible. They are too stiff, and in my experience, attempting to force them in can crack the pins and damage the piece itself.
So I set about trying to design some alternative pins for PLA. My first attempt was to make flexible end tabs, but while this worked, the gear heart axle is too short to support this approach. In the next attempt, I altered the internal structure of the tip of the pin to make it more flexible for PLA and redesigned the protrusions.
These new pins were designed using an ACIS solid in Shark FX (sfx file included) so will behave well with Makerware, ReplicatorG and skeinforge. They snap into place with moderate force and rotate freely.
Version 2 of the pins has 0.25 mm more protrusion on each side at the tip, they still insert with moderate force but have a firmer hold.
If you have already made Emmett's Screwless Heart Gears, then these pins are a drop in replacement. Simply download and print PLA-gear-heart-pins.stl file - that's all you need.
If you are using Makerware I would recommend at least a 0.2mm layer height, 3 shells and 15% infill. In ReplicatorG I am doing the same, but using the skin module to achieve a 0.1 mm outer surface finish.
HEART GEAR PLATES
If you want to make the PLA heart gears from scratch, simply download and print the two plates: PLA-gear-heart-plate1.stl and PLA-gear-heart-plate2.stl. The first plate includes my snap off ear raft print aids, to increase the surface area of the small gears to prevent them from breaking loose during printing.
Again, if you are using Makerware I would recommend at least a 0.2mm layer height, 3 shells and 15% infill. In ReplicatorG I am doing the same, but using the skin module to achieve a 0.1 mm outer surface finish.