⚙️ The Functional, Support-Free LEGO Technic 40-Tooth Gear ⚙️

Tired of failed LEGO Technic 40-Tooth Gear prints? So was I! Many digital models are simply copied from the original injection-molded part, which leads to huge overhangs and a bottom surface that looks like junk when printed using FDM printers.
 

This custom design solves all the common printing problems, delivering a gear that is 100% functional and prints absolutely support-free.
 

🛠️ Key Improvements for FDM Printing

I tackled the issues with existing gear files head-on:

1. Eliminated Supports: I redesigned the geometry to remove all necessary supports. I raised all the low points to the surface height, ensuring no portion of the gear body is "floating."
2. Added Chamfers: Overhangs on the gear teeth and around the axle holes have been replaced with chamfers. This allows for a clean, reliable print without sacrificing function.
3. Corrected Axle Fit: Unlike other support-free designs, I ensured the axle holes have the correct thickness and the small internal rim required for Technic pins and axles to snap in and fit all the way through the part.
4. Precise Scaling: The file was carefully scaled up from an initial reference to guarantee the exact size and gear pitch for seamless integration with official LEGO components.

🎯 Function Over Form

Let's be honest: this gear doesn't look as pretty as an injection-molded part. But if you're into Technic builds, you probably value function over form anyway! This gear is built to integrate perfectly into your mechanisms, handle load, and save you time and filament.

💰 The Perfect Bulk Gear Solution

Whether you're one gear short for a complex build or need to produce dozens of gears for a large-scale project, this file is your solution. At an estimated 8 cents per gear in filament cost, this support-free design is the most economical way to keep your Technic workshop fully stocked.

You will need to have your printer settings dialed in for the precision required of Lego parts.

Print Settings:

• Printer Type: FDM (Elegoo Centauri Carbon)
• Supports: NONE required!
• Material: PLA, PETG, or ABS (all the prints shown were done in ABS for durability)
• Layer Height: 0.12
• Infill: 20-30% (I used Cubic to strengthen in every direction)
• Wall Generator: Classic
• Walls Printing Order: Outer/Inner (for precision)
• Build Plate: Smooth

Enjoy your perfectly meshing, support-free LEGO Technic 40-Tooth Gear! If you like it, stay tuned, because I'll be designing many more of these gears in the future!