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INFILL

Ender X4

Made by: ading2210 // vk6

Repository link: https://github.com/ading2210/ender-x4

Total hours so far: 49

  • I have a 3D printer or will be getting one before March 21st

This printer is has been designed as part of Hack Club’s Infill event.

3/13/25 - Research design goals and feasibility (2.5 hrs)

I did these notes on a Google Doc originally, so here it is copy-pasted.

Goals:

  • Reuse as many parts as possible from 2 stock Ender 3 printers
  • Quad extruder with independent hotends (IDEX or single toolhead?)
  • Under $250, used parts allowed
  • Entirely off the shelf components and printed parts
  • Maximize build volume

IDEX Design

  • Need 4 x axis motors and 4 belts
  • Total motor count – 4 x axis, 1 y axis, 4 extruder, 2 z axis (total: 11).
    • 1 extra motor (Nema 17) needed for x axis ($10)
  • Control boards (option 1):
    • Main: BTT Octopus ($80)
      • Used for x, y, z axis and bed heater
    • Extra: 2x stock Creality v1.1.4 (or v4.2.7)
      • Used for all 4 extruders, 4 hotend heaters
  • Control boards (option 2):
    • Main: BTT SKR v1.4 ($30) + 5x TMC2209 ($20)
      • Used for x, y axis and bed heater
    • Extra: 2x stock Creality v1.1.4 (or v4.2.7)
      • Used for all 4 extruders, z axis, 4 hotend heaters
  • Control boards (option 3):
    • Main: BTT SKR Mini E3 v2 ($35)
      • Used for x axis and bed heater
    • Extra: 2x stock Creality v4.2.7
      • Used for all 4 extruders, z axis, y axis, 4 hotend heaters
  • Extra cost: $35-$90

Single Carriage Design

  • Only 1 x axis motor and belt
  • Total motor count – 1 x axis, 1 y axis, 4 extruder, 2 z axis (total: 7)
  • Control boards:
    • Main: BTT SKR Mini E3 v2 ($35)
      • Used for x, y, z axis and bed heater
    • Extra: 2x stock Creality v1.1.4
      • Used for all 4 extruders, 4 hotend heaters
  • Extra cost: $35

Attributes Common to Both Designs:

  • Ender 3 v2 Neo might be used instead because those are cheap on ebay
    • Otherwise use the Ender v3 v1 because that one is open source
  • 2 power supplies (stock ones used)
  • 2 of the hotends and extruders need to be purchased
  • Purchase 2 Ender 3 v1s used ($100 - $120)
  • Main computer is Raspberry Pi 3 with Klipper
  • Dual X axis gantry, dual z axis motors
  • Keep a belt slinger design
  • Use stock rollers for x axis (linear rails if within budget)
  • Keep stock hotend
  • Keep stock motors
  • Direct drive

4/1/25 - Frame, Y Axis (1.5 hrs)

I’m going to re-use the Ender 3 Y axis carriage and use the same design for the bottom portion of the printer’s frame. I don’t see a way I can improve the Y gantry without excessively modifying the parts, because the aluminum extrusions are already machined with slots for the Y axis gantry. Also, the various Ender 3 variants use slightly different Y axis gantries (this is pretty much the only mechanical change between the different Ender 3s) so making a single design to accommodate all of them is unrealistic.

4/2/25 - Frame, Start X Axis (1 hr)

  • Assemble the Y Axis and attach it to the frame
  • Start assembling the X gantry

4/4/25 - Continue X Axis (2 hrs)

  • Create mount for second X motor
  • Add motors to X axis assembly

4/6/25 - Create A/B Toolheads (10 hrs)

In my design, there are two different toolhead designs. The “A” toolhead is on the left side of the X gantry, and the “B” toolhead is on the right. The hotend assembly is mirrored on the B toolhead, but the extruder mount has to be different. The goal for the hotend assembly is to get the hotend as close to the center of the printer as possible. This allows the hotend on each toolhead to come close to each other while printing, thus maximizing the printable area.

Creating the hotend assembly was a bit annoying because of the unconventional layout. I need the hotend fan to be behind the hotend rather than in front of it, so the hotend can’t be directly mounted to the X carriage base. The fan duct for the part cooling fan was also a pain, but I’m going to blame that on my inexperience in modeling this kind of part in Fusion.

Following the hotend assembly, I moved on to building both toolheads. This was relatively simple, since I just had to attach the hotend assembly to the extruder and X carriage base. I also added a mount for a CR Touch probe on the A toolhead.

4/7/25 - Finish X and Z Axis (10 hrs)

First, I needed to modify my B toolhead design to add in a belt holder. This is because the belt for this toolhead will be placed well above the aluminum extrusion rather than around it like the stock toolhead does. This was a simple addition, and I used a model of a GT2 belt as a reference so I could make a cut of the belt profile.

I then finished one half of the X axis gantry, which contains both A and B toolheads on the same axis. The new additions here are the endstop mounts, belt tensioner, and the brackets on either side for the joining pieces to the other half of the X gantry.

To create the full X axis gantry, I copied the part shown above and rotated it 180 degrees. I added connecting pieces between the two halves, and attached the Z nuts to them.

In the full printer assembly, I added the extrusions for the Z axis as well as the X gantry. I made a mount for the Z motors, lead screws, and Z endstop.

4/8/25 - Finish Initial Printer Design (10 hrs)

Although the Z axis was complete, I still needed to put braces between both sides of the Z gantry. On top of these braces, I put the 4 spool holders as well.

Next, I modeled the mounts for the two PSUs and the power switch. I found that arranging the PSUs on their sides wastes the least amount of space, and simplifies the mounting hardware.

To mount the 3 control boards, I have them arranged in a rack, with each stacked on top of each other. This rack attaches to the 4040 extrusion on the base of the printer. I’m a bit concerned that there won’t be enough airflow across the control boards, but I’ll have to wait until this is actually built to see if that will be a problem.

I also quickly made a bracket for the Raspberry Pi 3. I used an RPi 3 instead of a newer model mainly because I already have one lying around. The other reason is that it’s significantly cheaper ($20 used) and I don’t need more processing power anyways. This bracket, just like the control board rack, attaches to an extrusion on the base.

The final item missing in the printer is the LCD mount and legs for the frame. The legs attach to the side of the 4040 extrusions on the base, and the LCD attaches to the front right leg.

And with that, the initial version of the printer is complete.

Here it is next to an original Ender 3 v1 for comparison.

4/9/25 - Design Revisions (2 hrs)

I added end caps to the 4040 extrusions on the base and chamfers to the legs to improve the aesthetics.

I also made the spool holder arms thicker in order to improve their strength.

Finally, I added chamfers to a bunch of other parts and fixed various errors with intersecting geometry.

4/10/25 - More Revisions, Work on BOM (3 hrs)

I went back and reviewed all the screw holes and made sure they were the right diameter. Most of them will be self-tapping, so I had to reduce the hole diameter to accommodate. I also changed some of the screw type which were used in order to reduce the cost. For instance, I replaced the usage of M2 square nuts in the belt tensioner to use M3 square nuts instead. This was so that fewer unique fasteners would need to be purchased.

I then put together a BOM for the printer.

A screenshot of the BOM

4/11/25 - More Revisions, Source Parts (4 hrs)

I changed the base of the spool holder to use two M3x16 screws on either side instead of two M3x35 screws that go all the way through.

The usage of 2.0mm thick M3 square nuts was changed to 2.5mm thick ones because they are cheaper and more commonly available.

I also researched every part I needed to buy and found that it barely fits in my $300 budget.

A screenshot of a spreadsheet with the costs of each part.

4/12/25 - Set up Repository and Publish (4 hrs)

I wrote the README for this repository, added more images, added the license and published the repo publicly.

I also made a PR in the Infill website repo to improve their build scripts. This journal markdown file contains a lot of relative image URLs pointing to files within this repo. Before, this wasn’t supported and I would be forced to replace all of them with absolute URLs.

4/14/25 - Order All Parts (1 hr)

I have ordered all of the parts from Ebay and Amazon. The total cost was about $340, $300 of which was covered by the Hack Club grant. The stuff on Ebay should arrive by 4/17 and everything from Amazon will arrive by 4/15.

4/15/25 - Research Klipper Configuration (1 hr)

While I wait for the rest of the parts to arrive, I spent some time researching how I might configure the printer with Klipper. Having multiple control boards is pretty trivial, but the tricky part is the X axis movements. Even though Klipper already supports IDEX printers via the dual_carriage config, it only supports 2 toolheads on a single gantry.

Thus, I need to manually set up the X motors and set the kinematics manually using GCode macros, similarly to this post in the Klipper forum: https://klipper.discourse.group/t/emulating-6-carriage-idex-by-syncing-steppers/18391/7

Another issue is that regular Klipper does not support multiple bed probes by default. Currently, I’m using two CR Touch probes for each X gantry, so this is a required feature for me. It seems that the Klipper for CNC fork does support this, but that fork comes with a bunch of other caveats.