10/19/2025 - Brainstorm and Product Research

(Polisi3D Pellet Extruder Component from Amazon)

(By Sealand/Blurolls3D on Aliexpress)

The goal of this project is to create a plastic pellet extruder for a 3D printer. The most difficult part is finding proper plastic extrusion components - specifically the auger bit and the heatsink/heatbreak. Since I don't want to spend thousands of dollars on a custom metal machined part, I will need to order parts from sellers already making the part.

I've narrowed it down to two options (well, they were the only two options). Both seem promising and potent to work with, but only the Amazon seller will give the drawings for me to recreate in CAD.
I'm not super sure which one to pick.

10/22/2025 8 AM - CAD of Hardware

I am currently completing the CAD for the hardware of the pellet extruder. I am recreating the hardware parts in CAD, so then I can design my extruder around those parts. This process is a bit challenging because I need to look at data sheets and technical drawings, and then find the best way to recreate the model in CAD. I think it looks decent!

10/22/2025 11 AM - I made a Variable Depth Plastic Screw!

I wanted to create a 3D model of a variable depth plastic screw for my Pellet Extruder. Prior to this, I was simply using an 8mm cylinder as a "placeholder" for the actual part. However, I wanted to expand my CAD skills and make the real thing. So, after a lot of brainstorming on how to make the coil "variable-depth" (meaning the inner diameter of the screw changes, goes from small to large), I used a cone shaped cut (revolution) and used Fusion's "coil" functionality. In the end, I got a model pretty similar to the manufacturer's model!

10/23/2025 - More CAD and Components

In this work session, I added more components to the CAD model, including:

• brass standoffs
• 5015 fans
• 4010 fans Note: the fans, I decided, to use generic Prusa i3 Mk3s fan hardware, since it is easily accessible
• started modeling structural 3D printed components
• added optional heatsink for nema 17 motor
  

11/3/2025 - Modified Geometry and Added Plastic pellet intake

Today, I spent some time brainstorming manufacturing - it's really easy to design something in CAD and not realizing that the geometry would be impossible to assemble in real life. Made some cuts and splits. I also created the inlet for the plastic pellets to enter. I'm thinking of using a cpap tube. Don't want to put too much weight on the extruder.

11/4/2025 12 PM - Created Part Fan Duct and Repositioned Fan

Today, I repositioned the fan, because after a ton of brainstorming, I realized having the fan stick out at a 45 degree angle would be hard to accomplish & made the extruder extremely bulky (this would mainly affect CoreXY printers). I also created a crude model of the fan duct. This was quite hard to do, and I watched a couple Youtube videos on lofting and sweeping, etc. I ended up with a rather simple duct, which will hopefully get the job done.

11/4/2025 3 PM - Fluid Dynamics Analysis (CFD) on new fan duct!

So I ended up going down a rabbit hole on fluid dynamics and simulations. Turns out, Fusion does not have CFD capabilities, so I ended up using SimScale. Took me a while to learn the software and successfully create a simulation. Looking at the simulation, the duct is not focusing the air and has too much room for the air to slow down, rather than directly hit the nozzle.

11/6/2025 - Second Fan Duct Iteration

Using the analysis from the Simflow simulation, I worked to improve the fan duct's part cooling geometry. So after some research (and facepalms), the part cooling duct should cool the part, not the nozzle. So, I lowered the duct and thus the air is not pointing more towards the part. In addition, I decreased the thickness of the fan duct. This should improve the airflow pressure onto the part. I also used a different strategy to model the part: I used a slot (sketch profile) and a sweep command to create the geometry. I will run a simulation for this part as well.
Side note: Fusion had updated and now there is dark mode!!!

1/6/2026 - WE'RE GOING ALL CUSTOM!!

So instead of worrying about the Funssor or Bluerols kit, I'm thinking of using a custom CAD design and fabricating that. Because I think the kits are too limiting. So I worked a bit on the auger, and made it for my needs!

1/8/2026 - Hotend Work

Added on to the work on the auger, I worked on the entire collective hotend assembly. I worked on the heatsink: more fins, thinner fins, and slightly smaller spacing. This allows me to have 1 more fin than the original reference model, giving better cooling (I may run simulations on this later). I also made flat cutouts on the heatsinks (like the Bambulab hotends) for compactability. Work is being done on the heater block, and it's coming together well.

1/10/2026 10 AM - More Hotend Details

In this work session, I made some more progress on the hotend design. I studied similar hotends like the Bambulab hotends to gain inspiration for the size and specs of the heatsink (E3D V6 hotend's heatsink is overkill for heat dissipation, so it's too chunky & takes up too much space & is too heavy. The Bambulab hotends are a lot more compact, and they are equally as effective in terms of heatsink heat dissapation). I also made the heater block more geometric and added set screw slots.

1/10/2026 12 PM - MASSIVE MILESTONE - Printer Integration

YESSS! It's all coming together now! So I made some minor tweaks, like adding a cover for the fan intake. Then, I did some research on custom hotends, and I found that I can adapt the pellet extruder for the Prusa i3 Mk3s. So I created and adapter for the Prusa i3 Mk3s, and voila! It's on there! I'm going to have to do some more modifications to make things a bit better, but it's all smooth sailing from here on out!

1/11/2026 - Quick test print

So in order to better understand the scale of the pellet extruder, I made a quick test print. I think 8mm diameter is a bit too small. Definitely don’t want it to be extremely large, but I want decently sized pellets to be fed in.

1/14/2026 - Revisions to Hotend Assembly

Made major modifications, but WAYYYY more modifications to come!
So I've definitely been bouncing back and forth on the manufacturing method I shall use to create the auger: of course a lathe or SLM/BJ 3D printed parts. I think SLM/BJ 3D printed parts have an aura of novelty, and that can be totally interesting.
So I was given a suggestion to increase my diameter from 8mm to 10mm. This way, larger pellets can be fit in. I also changed the way I CAD'd the auger. Instead of a "join" function, I used a boolean cut to make the auger geometry (using a coil in Fusion). I think the auger looks 10 times better, and also more pellets can be inserted. Also, I am hoping a geared Nema 17 will do... I don't want to deal with the elctronics hassle of using a Nema23. I'm looking to add custom heat dissapation geometries, so it will be very exciting. Also, a lot of the design is influenced by the proven: Greenboy3D pellet extruder.

1/16/2026 - Optimizing Thermal Conductivity

Today, I made a bunch of progress on optimizing the design for SLM 3D printing. I'm really taking advantage of the flexibility of SLM 3D printing (basically I can CAD whatever I want haha). I created some advanced heat disappation channels, so the barrel has varying wall thickness. I also plan on using a more sophisticated heat sink geometry, but that may be overkill. Since I made the auger 10mm in diameter, I also had to adapt that to the 8mm shaft collars.

1/23/2026 9:08 PM - Internal Geometry Enhancements

Did a bunch of research on SLM and BJ 3D printing processes. Definitely a lot more flexible than FDM 3D printing, since powder is acumulated layer by layer, but fillets are necessary

1/23/2026 9:09 PM - Thrust Bearing Incorporation

Spent a bunch of time figuring out how a thrust bearing is used - they are supposed to prevent backpressure from doing any damage to the stepper motor. I added a "shoulder" (thanks to the flexibility of SLM 3D printing) to slap the thrust bearing onto.

1/27/2026 10 AM - Thrust Bearing Incorporation 2.0

Realized the previous "shoulder" geometry was not going to work with generic thrust bearings, because the washers are of the same diameter. So I did some research, contemplated whether I should get better bearings, but then realized I should just modify the auger.

1/27/2026 1 PM - 3D Modelling 3D printed thrust bearings

So I'm too lazy and broke to buy thrust bearings, so I realized 3D printing them is a decent idea. I'll be using 8 ball bearings and just 3D printing the washer and bearing retainer. This is fine, since the rpm of the auger will be low, and I can just lubricate it a ton.

2/4/2026 2:30 PM - Redesigning Printed Base to accomodate new Hardware parts

So I'm creating a new housing to include the thrust bearings. Had to think quite a bit how the print would be oriented. In the end, I plan to print the part in two pieces, and then screw the two pieces together.

2/4/2026 2:47 PM - More work on printed base

Doing some more work on the printed base. Added some hex pattern air vents. Only on the front facing sides due to print orientation (the hex pattern will be on the bed). I also am working on a hopper for the pellets. The fans currently do not have mounting yet.

2/6/2026 - Working on Cooling

So I'm now working on the last bits (besides wire management): cooling. I think a lot of designs use 5015 fans. But I should probably do some research to see if they are overkill. I'm struggling to find good places to mount the fans. Lots of work to be done, and I definitely did a bunch of shifting around this session.