Lemontron Rev D

👇 Watch the reveal video! 👇

Lemontron is a new free and open source portable printer that is making the rounds online due to its unique form factor– Fitting in a box of filament, it sports a build plate comparable to a Bambulab A1 Mini and Prusa Mini.

The secret behind this incredible ratio is in the Drive system, which shares some similarities with CoreXY which drives a ton of modern printers. However the exact drive system is known as the Positron drive, invented by YouTuber “KRALYN” who released it in May of 2022.

Shortly after, Kralyn stepped away due to a career change where non-competes prevented him from participating. But his team eventually brought the well received Positron v3.2 kit to market with LDO Motors as a manufacturer.

While heads down working on the v3.2, several forks sprung up, including the Positron JourneyMaker who beat the v3.2 to market, and the newcomer, the Lemontron. Lemontron began as a unibody chassis mod for the JourneyMaker, but quickly grew in scope to a complete redesign that cut the cost in half.

In a small printer you expect to see a small price, and the Lemontron delivers on that expectation. A fully built Lemontron consisting of only off-the-shelf parts will run you $413.

The low price is all due to Lemontron’s complete redesign, in which custom CNC parts that increase the price of Positron kits have been cleanly eliminated without compromising performance.

In contrast, the Positron v3.2 and JourneyMaker are kits that integrate expensive CNC parts. A fully built JourneyMaker with a combination of self sourced parts and custom CNC parts from Voxolite Shop will cost you around $800, while the Positron v3.2 kit from LDO motors will cost you $699.

Video updates have been coming for the entire time and the latest one shows off the printer printing impressively large structures, showing a comically large benchy followed by a particularly challenging marble run model incorporating 80 degree unsupported overhangs which the Lemontron prints with ease.

Rev D - Changelog

This is the best update yet!  And once again it's backwards compatible, meaning all the 3d printed parts fit together in the same way.

1. New bracket! This update contains a beautiful and elegant new bracket that eliminates the collision with the tool head when using the extreme rear of the build plate. The new bracket is also much stronger with improved DFM; wafer head screws replaced the countersunk screws. The BOM has been updated to include the wafer head screws.
2. New heat set inserts geometry! This DFM update eliminates the need to clean up the severe blobbing from pressing in the heat set inserts, resulting in repeatable, beautiful inserts every time. Some of the inserts have changed sides too, eliminating the need for 25mm countersunk screws. Another screw bites the dust!
3. To eliminate the 25mm countersunk screw, I removed the countersink on the belt tensioner to accept the wafer-head screw instead (bonus: better DFM).
4. New part: Z-Axis spacers! It bothered me that the M3x6mm threads stopped short of the engaged material by almost 2mm. I solved that with spacers that allow the use of the M3x8mm instead. The spacers are a precise thickness to allow the threads to fully engage the (thin) plastic for the maximum possible strength!
5. Eliminated M3x6mm countersunk. It was also used on the Raspberry Pi, but that has been switched to the M2.5x6mm instead, based on feedback that some people are uncomfortable with how snug M3 fits in the Raspberry Pi mounting holes.

In this update, I was able to eliminate 2 screw types(!), bringing the total number of different types of screws down from 12 to 10.  I don't think I can reduce any further! The build guide has been updated with beautiful pictures to illustrate all the new updates. The only brand new screw is the 25mm wafer-head.

Rev C - Changelog

This update includes ONLY changes to the tool end (tool end, clip, clamp). The tool end  has improved strength, especially in the attachment screws area, so you can now tighten it to the carriage without fear of cracking it. Also, the 10mm M2.5 screws previously used on the tool end have been cleanly eliminated.

Rev B - Changelog

This update is backwards compatible with the previous revision, meaning all the parts fit together in the same way. This update contains the following quality-of-life improvements:

Overall Updates

• New Feature: Added compatibility with the LOP series of MeanMell PSU's. On the BOM I was recommending LOP's whereas in the video I used an EPP. You can still force an LOP into the Rev A chassis by carving out some material.
• Better DFM: Removed countersinks from Z Axis mounting holes. The switch to button head screws will make it more durable as counter sunks impart a stress on the seams.
• New Configurable Teardrop Angle: All 3DP vertical hole teardrops now use the User Variable TEARDROP_ANGLE. Adopted a 120deg teardrop for improved appearance by default.

Bracket Updates

• Fix: I have tripled the number of screws for the lead screw nut to match the video and build guide.
• Fix: In the video I used a bracket which I countersunk with a tool, but now the bracket will have the chamfer built in.