Lemontron "Endgame Revision" Annoucement
After a full year of design, testing, and refinement, the Lemontron has reached what I’m calling the “Endgame” milestone. The Lemontron has upgraded into a far more capable machine: Stronger, cooler, easier to build, and dramatically more rigid & repeatable.
This update is the cumulative one-year overview of changes across Revisions B through E, driven by community feedback, discoveries, and a relentless attempt to squeeze more performance out of the space-constrained form factor.
Below is an overview of what’s changed:
A New Extruder: The Endgame Lemonstruder
The biggest leap forward is the new 4.5:1 geared extruder. Earlier versions relied on a hob mounted directly to the motor shaft. That approach worked-sometimes-but it also ran hot, offered very little mechanical margin, and behaved inconsistently depending on the motor.
The new design uses a 16-tooth drive gear, a 72-tooth reduction gear, and a larger intermediate gear riding on a post. The result is:
- High torque with stable grip
- Minimal heat transfer to filament
- Faster flow rate, exceeding 43mm³/s
- Good thermals even after long heat soaks
It’s compact, powerful, and finally feels like the extruder this printer deserved from the beginning.
The 225-Degree Wraparound Cooling Duct
Strong part cooling airflow has always been a challenge in such a cramped tool head. After multiple failed designs—including dual ducts, a 180-degree curved outlet, and even a full 360-degree “ring” duct, I landed on a 225-degree wraparound that unlocks the fan’s full cooling abilities.
This design:
- Delivers most airflow to the front where it matters
- Routes a controlled amount to the sides and rear
- Avoids internal restrictions that choke the fan
- Has large directed outlets
Full Chassis Cooling Overhaul
Paired with larger fans, this system outputs 8× the airflow of earlier prototypes.
- Fans directly cool the motors, design inspired by art_nattanon- a fan is touching each motor
- Quad nearly-chassis-height fans
- Optional copper VRAM-style heatsinks for additional surface area
This helps the motors, especially the extruder, stay cool and stable during long prints, which directly fixes most print issues.
Structural Improvements Everywhere
Many of the most impactful changes are subtle: geometry tweaks, reinforced features, and progressively more thoughtful design-for-manufacturing decisions. A few highlights:
- Stronger Z-Block: Shifting the motors outward allows more material where it matters most, reduces flex, and enables the use of preferred bearing sizes.
- New Lead Nut Seat: A taller, reinforced seat prevents Z-offset drift—even when printed in PETG.
- Probe Mount: Revised walls prevent cracking of the probe’s mounting tabs and improves durability.
- Relocated Tensioner: Instead of hollowing out the critical Z-block, the tensioner now sits at the front and pivots around the motor screw. Cleaner, stronger, and simpler.
- Updated Bracket + Edge Connector Fix: A new receiving channel fully restrains the PCB tab in the edge connector, eliminating the up/down play that caused Z-offset shifts.
- One-Handed Bed Assembly: Added guide rails allow you to drop the bed holder into place with a single hand.
The Screw Elimination Saga
From Rev A through E, I’ve been slimming down the BOM. Every unnecessary fastener is one more part to track, buy, and install. Over time:
- Screw types dropped from 13 to 7
- Various countersinks were swapped for stronger alternatives
- Short screws were replaced with longer ones + printed spacers
- Raspberry Pi mounting switched from M3 to M2.5
- Heat-set insert geometry was optimized while reducing screws as a side-effect
It’s not glamorous! But the payoff is a printer that gets ever closer to building itself.
A Genuinely Useful Tool
All of these improvements translate to genuinely better prints. Rev E is capable of strong, reliable, repeatable outputs, even on long prints or with challenging materials. This machine has become a real daily driver.
What’s Next?
There are still frontiers I’m exploring:
- Full direct drive: likely impossible within the current folding geometry, but still on my mind.
- Vertical fine artifact (VFA) reduction: possibly belt-related; a 6 mm belt experiment is on the horizon.
No promises on timelines. This project has been a labor of passion, often at the expense of more practical opportunities. As I’m currently between jobs, but Patreon support sure helps.
Time For You To Build One
If you’ve been waiting for a moment to start your build, this is it.
Video breakdown, files, and community links are available on the site.