Heavy Duty Herringbone Gears for M8 or 9/16 (14mm) Bolts

8/10/17
I ran the 9/16 (14mm) version through netfabb and rolled the gear by 180 degrees. Sorry about that, but the original printed just fine.

7/9/17
This update is long over due. I included a gear for those eBay sellers passing 9/16 bolts as M8s! Also, I increased the axle distance to fit more custom wade designs.

9/30/14
I decided to replace my gears, but couldn't find ones with a gear ratio other than the stock 47:9 gears. I found thicker gears for Prusas, but because they use different hobbed bolts, they weren't physically compatible with my extruder. Even after tinkering with washers/spacers, I had X carriage clearance issues.
So I made my own herringbone gears with a 37:13 gear ratio.

These gears are direct replacements for stock gears, but more durable.
They're perfect for those with dual extruder setups.
WARNING: even though they're direct replacements, you still need to modify your firmware! You need to change the E steps in your configuration marlin file. Change E to "424", compile, then upload to TAZ.
DEFAULT_AXIS_STEPS_PER_UNIT {X,Y,Z,424}
If you don't change your firmware, these gears will not work!
Also, make sure to read the instructions!