Faster Printing requiring Filament Buffer feeding

[NikosSprocket]

My Voron 2.4r2 350mm custom toolhead upgrade is closed to completion; nozzle camera and final nozzle LEDs placement is under works.

I am extremely happy with the print quality and speed, this new toolhead can print with the massive cooling and compact footprint as I print almost everything with Object-by-Object sequence.

I had printed a lot of PLA (+, Silk, Matte), ASA and TPU (95 & 83) and the only limiting speed factor was the 0.4 nozzles max. volume speed; still plenty fast for me at list!

A few weeks ago, I printed some large floating ghosts (~183 x 184 x 256 mm tall) using Polymaker Glow (PLA) filament. I noticed a few areas were "missing" filament, so I started investigating where is the issue. Conclusion, this filament is unusually stiff and abrasive for PLA, Polymaker recommends "Hardened Nozzle". That apparently created a lot of friction inside the PTFE feeding tube (using in mm 4 OD, 3 ID PTFE) and at times the extruder was slipping. When I tried to manually pull filament at the end of the PTFE tube just before the extruder, I found out that it needed a lot of effort to pull this filament.

In conclusion, I am looking for some mechanical way to "push gently" filament at the beginning of the PTFE tube to help with the increased friction and eliminate "filament starvation".

I have found Mellow LLL Plus Filament Buffer which I think is similar with the TurtleNeck Pro from TurtleBox Project. Unfortunatly implementing TurtleNeck requires some toolhead mod. like FilamATrix.

Any thoughts?

Edited November 6, 2025 by NikosSprocket

[Jerazmus]

That filament buffer is quite good. I use it on my RatRig VC4 500. I have a looong PTFE tube and this is the only way to reliably keep the filament at the ready for the Extruder. Otherwise there’s way too much friction for the Extruder to pull all the way from where it is. I also did not want to rework where my filament is feeding from so this is a perfect solution. They also have an older version LLL buffer that doesn’t have a stepper motor as it’s driver mechanism but the one you have a link for is the one you should use if that’s the way you want to go. I recommend it though. 

[Repman]

12 hours ago, NikosSprocket said:

That created apparently created a lot of friction inside the PTFE feeding tube

I observed some similar phenomenom whenever I changed the filament from PLA to ABS and PETG to ABS (not all are effected, but sometimes it happend). It was that bad that feeding stopped completely and the drive gears were grinding the filament. Than I changed the PTFE tubing and everything was ok again. My personal opinion: Especially PETG tends to deposit some ingredients over the time onto the tubing surface which leeds to higher friction. But I have no study about that...

Anyway a pre-feeder would be a good thing but makes the whole process more complicated again.

[NikosSprocket]

13 hours ago, Jerazmus said:

That filament buffer is quite good. I use it on my RatRig VC4 500. I have a looong PTFE tube and this is the only way to reliably keep the filament at the ready for the Extruder. Otherwise there’s way too much friction for the Extruder to pull all the way from where it is. I also did not want to rework where my filament is feeding from so this is a perfect solution. They also have an older version LLL buffer that doesn’t have a stepper motor as it’s driver mechanism but the one you have a link for is the one you should use if that’s the way you want to go. I recommend it though. 

Many thanks for the info. @Jerazmus. I will decently look for the stepper motor version for sure; thanks again.

[Jerazmus]

@NikosSprocketthe buffer you have a link to in your post is the correct one I am speaking of. You can even see the stepper on the side of it in the picture when clicked on. And no problem. Glad to be of any assistance!

[lawson.brian]

If you are looking for single filament assistance you could look at this project:

DW-Tas/EMU: The [E]xpandable [M]ulti-material [U]nit.

Still in the beta phase but I have finished building a 4 lane version of this MMU and am in the commissioning phase myself. Development has been pretty rapid so far but the design is now relatively stable. As a single unit it would provide load / unload / feed assistance.

I would say it will require Happy Hare even as a single unit to drive it.

Under current testing, one of the developers is up to 8 lanes operational.

Edited October 31, 2025 by lawson.brian
clarify

[Penatr8tor]

This is the first time I've seen this type of device. I have to say I really like the idea of a buffer. Reducing filament path friction has been a challenge on more than one of my printers. Strictly from an engineer's perspective and having only read the description, the Mellow looks to be the best choice for me. I have pretty simple setups where I'm just feeding the filament from a box alongside the printer and I would be lying if I said I never had a jam. I think at the very least I'd like to try one of the Mellow units once I get my VzBot refurbed.

[Jerazmus]

15 minutes ago, Penatr8tor said:

This is the first time I've seen this type of device. I have to say I really like the idea of a buffer. Reducing filament path friction has been a challenge on more than one of my printers. Strictly from an engineer's perspective and having only read the description, the Mellow looks to be the best choice for me. I have pretty simple setups where I'm just feeding the filament from a box alongside the printer and I would be lying if I said I never had a jam. I think at the very least I'd like to try one of the Mellow units once I get my VzBot refurbed.

They are very good and worth it. All bambu printers do the same filament buffering standard. I know that’s not a comparison, but it just goes to show you that it’s a helpful motion for the system. It also helps with even extrusion as the actual extruder is not pulling the filament from the spool

[NikosSprocket]

@Jerazmus do you installed the Mellow Filament buffer at the very end of the PTFE or somewhere in between?

PS. I am putting an order for it; plus version of course!

[Jerazmus]

@NikosSprocket you can put it anywhere in the line. Middle is usually a good place. That also allows you to mount it on the frame rail or something. As the filament pulls from the Extruder, the buffer will sense that and feed. Then once that buffer zone is filled, it will stop, then the cycle starts over again. Over and over and over again. It’s a great tool. 

[NikosSprocket]

Thank you @Jerazmus. That sounds good.

Nikos

[Penatr8tor]

On 11/6/2025 at 2:07 PM, NikosSprocket said:

PS. I am putting an order for it; plus version of course!

Hahahaha 

I'm way ahead of you brother. Ordered 2 kits last week, should be here next week some time. So, I'm already printing parts.

Let me make your life a lot easier...

Mellow LLL Plus STL's

Button_Mellow LLL Filament Buffer v1 (2).stl

Filament Exit Tube_Mellow LLL Filament Buffer v1.stl

Idler_Mellow LLL Filament Buffer v1.stl

Top Cover_Mellow LLL Filament Buffer v1.stl

Filament Entrance_Mellow LLL Filament Buffer v1.stl

Housing_Mellow LLL Filament Buffer v1.stl

Top accent Plate_Mellow LLL Filament Buffer v1.stl

 STEP Assembly:

Assembly_Mellow LLL Filament Buffer.step

Fusion 360 Assembly

Assembly_Mellow LLL Filament Buffer.f3z

It took a while to find the CAD files. They were all in Chinese and I had to upload them one at a time and resave them and make an assembly.

There's a video that shows how to assemble and the Documents are here...

 

[therm_virtual0y]

I have everything built and new firmware but am wondering why the docs are telling me to hook the buffer to my main board instead of using it as a mmu.  I guess I just assumed with the ease of adding remote devices to Klipper that all I would need was a usb instead of running wires from the buffer to my motherboard.  kind of disappointed.

[therm_virtual0y]

I was able to flash Katapult and Klipper and run this as another MMU with some great work from @ss1gohan13 on Discord.  
He shared his Git there on Klipper channel under Klipper mods.  Also, some discussion in Mellow/klipper config.
https://github.com/ss1gohan13/BufferPLUS-klipper

Edited November 17, 2025 by therm_virtual0y

[NikosSprocket]

Great find @therm_virtual0y.

I am waiting for my LLL PLUS to arrive and try it.

The firmware is located at FLY-LLL PLUS Buffer. (Edit) It's the same link with @Penatr8tor information 

Btw, they just released a new firmware v1.1.2!

Edited November 17, 2025 by NikosSprocket

[ss1gohan13]

31 minutes ago, NikosSprocket said:

Great find @therm_virtual0y.

I am waiting for my LLL PLUS to arrive and try it.

The firmware is located at FLY-LLL PLUS Buffer. (Edit) It's the same link with @Penatr8tor information 

Btw, they just released a new firmware v1.1.2!

Looks like they also just released 1.1.3.

 

And still no proper klipper MCU support.

[therm_virtual0y]

5 hours ago, ss1gohan13 said:

Looks like they also just released 1.1.3.

And still no proper klipper MCU support.

Yes, thank you for your work on it.  I was disappointed that it didn’t connect via usb and needed I/O wired to work.   

[Penatr8tor]

17 hours ago, therm_virtual0y said:

I have everything built and new firmware but am wondering why the docs are telling me to hook the buffer to my main board instead of using it as a mmu.

Looks like the designers of the buffer never intended that the end user would want to send commands to the unit via Klipper. It looks as though it's treated like a standard filament run-out sensor that you plug into the controller like any other filament sensor. I say this because I remember reading that the buffer only needs power to do buffering and the rest is handled in firmware. The run-out detection is wired like any run-out sensor. 

That's where ss1gohan13 comes in. He sees that it uses an STM32 chip and thinks... hey, I could really give the end user a lot more control if I connected to the STM32 via klipper.

I design medical devices for a living, things like smart pumps that breakup clots in stroke patients, endoluminal fastening devices that are articulated with servos, various scopes and other electromechanical devices and they all share one thing... They all use STM32 controller chips. Granted they could be controlled remotely, but they don't, they all use embedded software to do their work behind the scenes internal to the device.

Of course, I'm just speculating on what and/or why Mellow did what they did, I just wanted to point out, in my usual overly long and drawn-out way, that just because some device is using a chip that can be controlled via klipper... the original design intent might not have been to control it that way.

But... We're all hackers and hackers will hack and IMO, that's a good thing. 

I just got mine in the mail this past weekend, today I'm going to print up parts and maybe put one together this afternoon.

[ss1gohan13]

If everyone can give me a little more time to work on this, I'm happy to try and make the config better. 

One of my biggest goals was to have this device not appear as an additional extruder on the system. With that, I believe that I over complicated the in's and out's of how I was remembering the buffer to work OOB. 

My overall goal is to achieve/keep:

- Remove the "extruder 1" from the config
- Auto filament loading until the buffer hull sensors trigger
- increase the feed speed/alter the feed rate/remove pulsing

And the basics like filament run out. 

EDIT:

If anyone wants to fork what work I've done thus far, please do so. 

Edited November 17, 2025 by ss1gohan13

[NikosSprocket]

I will definitely give a try to @ss1gohan13 klipper implementation after do the initial installation.

@ss1gohan13 will let you know of any findings.

[Penatr8tor]

@ss1gohan13 Good to have you onboard! I want to try the stock buffer running as a standalone unit. I don't need the filament sensor ability b/c I already run orbiter extruders with their sensor installed. I really just need a buffer to prevent false triggers on the Orbiter sensor from a kink in the filament or because it has to pull hard at the end of the spool. Of course, having the ability to customize setting would be a big benefit and I think your software might be the ticket so, thanks for diving down the rabbit hole.

[therm_virtual0y]

I must have fat fingers because I put the Discord name wrong.  I added an @ for some reason.

ss1gohan13

[Penatr8tor]

1 hour ago, therm_virtual0y said:

I added an @ for some reason.

Ya gotta be careful adding @ to ss you end up getting @ss. 

[therm_virtual0y]

That’s why I had to put it straight lol

[therm_virtual0y]

Sorry for the mistake ss1gohan13