Work in Progress

I bet you didn't know: February 16 is SMuFFs birthday. YAY!

Let this sink in: Five years ago I've presented the very first SMuFF to the public on Thingiverse. No wonder I sometimes call it my baby. Baby turned 5 today!

As one can tell from a look at the picture, since this day a lot of things have changed. Going from 3 stepper motors, using a spindle for the Selector and a Revolver design to V6, a sleek design with a belted Selector and a servo as the Revolver replacement, just to name a few. If you're interested how it became to be, you can read it all up on the Background page.
Most of the changes were focused on making it simpler and reducing the overall costs but also increasing reliability.

Now, 5 years down the (sometimes bumpy) road, I consider this project mature and stable. The only DIY MMU/Extruder solution that's not focused on only one 3D Printer ecosystem.

Often copied but never equaled!

Maker Pirpolo over on Discord just posted his take on the SMuFF, which deserves some credit. 

Not only he shows his (very appealing) integration of the SMuFF into an Ikea Lack table, but also some innovative modifications. The Filament-Wiper for example has got a silicone pad to go easy on the nozzle and the Cutter was modded to reduce the overall Z-Height.

Head over to this Discord channel, to read his full story and his motivation behind. If you like his approach, make sure you give him some credit.

I'm pretty confident, this is not his last contribution to the SMuFF project.

Pirpolo has published this solution on Thangs and has also set up his own page, where he will comment his build and his future progress. Go check them both out!

I've played with this thought for a long time, because the configuration for building the SMuFF firmware is a bit complex and might intimidate newbies quite a bit. Even if you're not a newbie, switching from one configuration to another can be annoying (I can tell, I'm doing it all the time). Because the latest firmware additions made it more worse than better (just think about all the different build environments in the Project Tasks treeview), I decided to give it a try, although, seemingly, no one before tried this approach.
Luckily, PlattformIO allows using any Python package in the pre/post build scripts if needed.

So, I completely overhauled the script that was printing out the build configuration and replaced it with a dialog window, based on the Custom-Tkinter package.

This dialog enables you to pick which option you want to include in your SMuFF firmware simply by clicking on it. Thus, the Project Tasks treeview now contains only the build environments for the base configuration of the different boards and hence, it got small and tidy.

When you start building the firmware by clicking the button, you'll find a new readme-build.txt file in the output folder, which lists all options used in this particular build.

I've realized that BigTreetech tends to bundle the SKR E3 V3.0 controller board with the BTT-TFT 3.5 E3 edition, which makes sense in that way, that the SKR board is meant as an replacement of the original Creality controller board.

Until now, the (new) electronics housing I've designed for the SKR E3 V3.0 was not able to contain the Ender-3 display due to size constraints. Hence I've designed a new housing, so those of you who got the bundle have something to work with.

I've published the STEP file on Thangs. STL files can be found on Printables. 

The easiest way to connect this display with the SKR E3 V3.0 is to attach it via the 10 pin flat ribbon cable on EXP3 and compile the firmware with the -D USE_CREALITY_DISPLAY and -D USE_FAST_SW_SPI options.

I've been already speculating whether one BTT 2.4/3.5 V3.0 display would be sufficient for both, the 3D printer and the SMuFF and now I've tested this theory successfully!

If you happen to own one of these displays and you've set up the communication to your 3D printer via serial connection (a.k.a. "Touch mode"), then you're able to connect the SMuFF controller board to the very same display, using the EXP1/EXP2 or EXP3 connectors on that display. Switching between both devices can be achieved by touching and holding the display for about 3 seconds. The display will pop up the selection menu, where you either pick "Touch mode" or "Marlin mode".

You'll notice a small lag when switching back to "Touch mode", since the display needs to reestablish the serial connection.

In the past, I've refused to add pre-compiled firmware binaries to my Github repository, simply because all the possible permutations were too extensive*. But since most of the supported controller boards are outdated now and the firmware isn't changing as frequently, I've decided to add the latest binaries (V3.21), supporting the following hardware:

• SKR E3 V3.0 controller board

• MiniPanel 12864 display (from  either FYSETC, BTT or MKS)

This makes it easier for new makers to flash the firmware on the controller  board without the need of installing the development environment and compiling the firmware. 

This update mostly concerns those who'd like to integrate the NeoPixel tool LEDs on their SMuFF without the hassle of fiddling them together.

By accident, I recently found out that the 144 LEDs per meter NeoPixel strip has the ideal spacing of 7 mm in between two LEDs. Thus, 3 of them will fit perfectly on one of the 21 mm wide Filament-Guides. 

So, no more cutting and laborious soldering of single NeoPixels. Simply cut the strip at 3 times the number of tools you have to length and use them. 

The new firmware lets you configure the amount of LEDs per tool easily in the Display menu or in SMuFF-WI.

And if that ain't fancy enough for you, let me tell you that there are also 332 LEDs per meter strips with a LED spacing of 3 mm - means 7 of them will fit one Filament-Guide/tool...
But, keep in mind: On a 5 tool SMuFF this 332 LEDs/m setup can easily draw up to 2.1 Amps from your 5V rail! On a maxed out SMuFF (a.k.a. 12 tools) the power consumption may exceed 5 Amps, which - in most cases - will overwhelm the buck converter on the controller board you're using! So, make sure you're powering the NeoPixels from a separate 5V buck converter which is able to deliver enough juice.

I'm currently working on a solution for a 2nd endstop on the LGX-Lite Direct Drive Extruder and I've come up with this.

It's consists of a new 3D printed frontplate that replaces the original one and which allows you to mount an endstop switch and take the 5 mm steel ball, which will trigger/untrigger the switch as the filament passes this spot.

Though, to accomplish this, you'll need to drill a 5.5 mm hole into your LGX-Lite in order to free the filament path and allow the steel ball to be pushed by the filament once it reaches this position. Keep in mind that this procedure will void your warranty for sure and, if not done correctly, can destroy the function of your extruder!

I'm using the FYSETC endstop switch (with the switch lever removed) because it's easy to source, easy to mount and - most important - gives me a visual feedback when/if the switch is triggered. Though, a standard microswitch, with only GND and Signal connected, will do the job as well.

I haven't tested it fully yet (i.e. attached to the SMuFF) , so stay tuned for further findings from my side.

I somehow have the gut feeling, that the SMuFF firmware needs a bit of tweaking for this solution to work reliably.

Inspired by maker EatMyNoodle in the Discord community, maker Defenc has SLA printed all the SMuFF parts out of translucent resin. After printing them, he specially treated the parts by sanding and coating them, in order to get them very translucent and very shiny.
The result is a SMuFF where you literally can see all the moving parts, which  are usually covered up by plastic, and hence watch it in operation (i.e. feeding the filament).

Just for the sake of inspiration and a bit of "bling-bling", this is what his SMuFF looks like when you have the tools NeoPixels attached to it.
If you'd like to see more of it, head over to this channel on my Discord server.

This is now the 3rd (and last) PCB I've designed for the SMuFF. It's the SMuFF NeoPixel board, which is used to mark the current tool and various states on the SMuFF (as mentioned here).

All three PCBs (SMuFF Backbone, Connector and NeoPixel) are meant to support new SMuFF builders and help them to overcome the hurdles of DIY electronics.

Just added this little board to my collection of SMuFF PCBs. 

This PCB is not a 'must have' but a 'nice to have' gadget, which makes wiring up the SMuFF even easier. It is meant as a replacement  for the 3D printed JST holder, that fits into the left Base. All you need to do is to cut it apart and solder the two pieces together, using an angled 20 pin wrap connector  (1.27mm) and standard JST connectors for easier access. 

I've created a new (experimental) branch for my OctoPrint plugin on Github.

This version is meant to handle two SMuFFs for an IDEX machine. 

The code uploaded has been tested and is working with two (independent) SMuFFs connected to the Raspberry Pi, which have to be configured as such in the SMuFF settings of OctoPrint.
The new plugin will translate tool numbers on its own, which means, switching to T5 on two 5 materials SMuFFs will automagically become T0 on the 2nd SMuFF. If configured for "Dual SMuFF", the navbar will show status information for both of them. Also, the SMuFF tab will let you switch between instances in order to control each SMuFF individually by using the buttons.

Anyways, I'm not quite sure if it'll work on an 'real' IDEX machine without some major changes in Marlin itself. Marlin supports either multiple extruders or multiple materials on a "Single Nozzle" but not both. Hence, I guess, getting Marlin to work with some kind of mixed mode will require heavy re-coding. 

I don't have an IDEX machine, so my testing capabilities are pretty much limited on this topic. 

If you'd like to give this modified plugin a try, please let me know over on Discord. Please keep in mind that this plugin is still considered as "Work In Progress".

I've stated many times that the SMuFF can improve a 3D printer extruder, even without using a DDE and here's the proof.

I've printed this Pin-Support-Challenge model on my ZEvolution II printer, a typical cartesian bed-slinger with Bowden style extruder.

If you want to test you printer, here's the link to the model generator.

I got inspired by Igors video on his channel (My Tech Fun) on YouTube.

Here's a very short video of a modified Filament-Cutter design published by maker Exsurge MechPrints (a.k.a eye_floaters over on Discord).

He added a small stepper which ejects the cut-off filament tip, which - I think - is a clever addition.

He promised to make a longer video as soon as he added that to his printer.

Hop over to his channel and leave him a like if you want to see more of this in the near future.

Been tossing around some ideas for the Filament-Cutter-Base-Module and I came up with this one: Filament-Cutter without the need for a servo.

Maybe yet another nutty idea but maybe useful, who knows...

I haven't tried it myself but if you do, drop me a note.

Please keep in mind: This model has to be seen as a "template", since you'd need to modify it to fit your printers geometry as well as your hotend.
Also: This is a generic solution, not a SMuFF specific one. You need to position the print head and cut the filament via GCode from within your "pre tool change" script.

STEP file has been published on Thangs and Printables. 

Go and check it out if you like.

I've released my 170+ pages Build Instructions a.k.a. Assembly Manual to the public. 

At this point, a big shout out to the few people who donated in the past and kept this project going. 

If you feel like, you still can donate. The details on how to do that you'll find on the  "Assembly Manual" page.

I've updated the Build Instructions for the Smart Filament Buffer PCB and added the configuration "How to" for it as well.

Also, if you haven't read it on the Discord channel for the SFB already, I recently added the feature to Daisy-Chain multiple SFBs into one "big buffer" to the SFB firmware. More details about this option here.

I've published a new version of my OctoPrint Plugin, along with an updated version of the SMuFF firmware (V3.13) today.  If you have the previous version installed, the OctoPrint Plugin-Manager will pop up a notification for an update automatically.

The new plugin - version 1.2.0 - needed an update, because the old one couldn't handle some of the new firmware options. While I was at it, I also added a  SMuFF dedicated tab, which you see in the picture to the left. It has got an output window, similar to OctoPrints Terminal output, which receives useful messages while the SMuFF is operating. So, there's much less need to parse the SMuFF log file if something doesn't work as expected.
I also added some buttons, which are capable of sending the most common commands to the plugin, such as Status, Wipe, Cut or Reset Jam. Hence, you don't need an additional plugin and must not memorize the SMuFF pseudo GCodes (@SMuFF ...).
The SMuFF status panel in the top bar also got updated and it now shows both endstop states,  which may be important for DDE users. Besides, it will turn read if the SMuFF has run into a jam while trying to feed the filament.

Internally, I've split the core functions, responsible for the communication  with the SMuFF, into a separate file, which code will be shared with the Klipper module in the future and thus, will make it easier for me to maintain both systems.

Please keep in mind that you have to update your SMuFF to firmware version 3.13, in order to run this version of the plugin!

As already mentioned in the first Multiservo announcement, I wanted to design a new PCB, which will combine the most needed components to build and run your own SMuFF V6.  My design goal was to gather the following components all in one place:

• Buck Converter

• Shared-Stepper option

• Multiservo option

• Remote control option

The size of the new PCB is designed to be the same as the Velleman 4-Channel Relay board, so that it'll fit in the existing housings and thus will be easy to replace (in case you intend to do so).

As you can see in the pictures, I've picked a MP1584EN Buck Converter, which is small, widely available (even in local stores)  and can deliver up to 3A of current but there's also enough space for using a SY8205 (a.k.a MP2482) module instead, which promises to deliver up to 5A of current and comes preset to +5V (I posted about the SY8205 down below). This PCB also uses the PCA9685 I2C LED/Servo controller and can handle up to 8 servos (or LEDs), whereas 3 of them are already taken by the SMuFF (for LID, WIPER and CUTTER servos).
For the Shared-Stepper relay part I've re-used the design of my mini relay board although this time it utilizes an ULN2003 chip to drive the relay coils. This makes hand soldering this PCB by far easier, in case you decide to do so.

The board is being controlled solely using the I2C/TWI interface, which makes is much easier to integrate with existing (or upcoming) controller boards. On the SKR E3 V2.0 or V3.0 for example, the existing SERVO header is being used in combination with a software I2C library.

The only thing for me left to do is to order this PCB and test it. If the chip supplier gods are with us, this could be rather sooner than later but these days you never know...

If you're eager to order and solder this board yourself, drop me a note on Discord.

The schematic for this board has been published here, on the Schematics page.

I've published the designs for the housings of the Multiservo option over on Printables  (STL) and Thangs (STEP). There are two versions available, one for the standard Multiservo board, one for the FeatherWing Multiservo board, which I highly recommend, because it has the smaller form factor and the SMuFF firmware will support up to 8 devices (Servos) only.

Although the goal is to have a dedicated custom PCB for the Multiservo option, you might want to upgrade your (existing) SMuFF using one of the Adafruit Multiservo boards right now. The FeatherWing version of the Adafruit board will fit nicely into the SMuFF Base-Right part, although it needs some modifications of the part to add some screw holes for mounting it (see picture 3 on the left). A detailed "how to" for the wiring of the stock boards can be found here.

Keep in mind: You'll need to have at least SMuFF firmware version 3.12, which already has been released as well.

The Multiservo option was first introduced in SMuFF firmware version 2.12, so it was basically just sitting there for ages and waiting for action. Originally, I have planned this option for a different SMuFF variant, which - as some of my other ideas - never have seen the daylight, simply because they didn't satisfy me.

But recently I played around with the latest firmware version and I figured, that some of the issues I had in the past were all related to the integrated servo control, which is a timer driven interrupt handler that serves all servos at once. If  I could only get rid of that piece of code, servos could run much smoother and the "old" Multiservo option came back to my mind.

I've published version 1.19 of the SMuFF-WebInterface, which has got a major addition: The Settings Wizard.
This Wizard will pop up after the very first connection and guide you through the major settings needed to get your SMuFF configured correctly.

Some of the options in the Wizard are preset and they're coming from the connected device itself. Settings not gathered by the Wizard are supposed to be default (such as endstop trigger states), if you've built the SMuFF according to my instructions . Some other settings such as the Step Direction of Selector and Feeder are supposed to be configured later on, since those depend on your wiring.

In case you've set up your SMuFF already, simply skip this step (tick the "Don't show this Wizard..." checkbox in the corner) and it won't bother you again unless you ask it to by clicking the button in the footer of the page.

The latest version also got a bit faster while it's connecting to the device and it also shows you a progress bar while it's fetching settings from the SMuFF.

Check the new SMuFF-WI out at this link.

Today I've published a new Filament-Cutter variant for the Bondtech LGX-Lite over on Printables.com and Thangs.com.

This version is more like a template than a complete integration of a hotend for a specific printer.

I had to make this version a bit smaller, so that it fits on the LGX-Lite and it also doesn't integrate a 2nd endstop switch, which is needed for the SMuFF in DDE mode. This task seems a bit complicated, since the tension lever doesn't function as with all the other extruders. I've got some ideas in mind but for the realization I'd need a real LGX-Lite to test with.

Meanwhile, you have the option to download the STEP file and check if you can find a nifty solution to this problem. 

I've finally found some time to work on the Klipper implementation for the SMuFF. In hindsight, the implementation was straight forward, but it took me a little while to browse through all the Klipper documentation and source codes to figure what's really needed.

The implementation consists of a config file (smuff.cfg), which contains the basic setup, a couple of tool change macros and some convenience macros, which can be used for the integration into the Mainsail Dashboard. Then there's also a corresponding Python module (smuff.py), which has to be copied into the specific Klipper folder extras.

The communication with the SMuFF happens via the serial interface, just as it did with my OctoPrint plugin. In fact, the code base is mostly the same as for OctoPrint.

After a couple of weeks of programming and testing the hell out of the new SMuFF firmware version 3.0, I'm pleased to announce that everything seems to work as expected. With everything I mean:

• porting the firmware to the Arduino Core STM32

• testing (almost) everything on the "old" controller boards (E3-DIP, V2.0, Mini)

• testing everything on the new E3 V3.0 controller board

• testing every display in combination with every board

What's left is testing on the E3 V1.2, because I don't have a working one to test with. Though, I'm not much concerned about that.

While doing all this, I had to change/rewrite a lot of files and even modifying some of the libraries used in this project.

So far, I'm happy to report that the new SKR E3 V3.0 is fully qualified as a SMuFF controller board. It even comes with a spare I/O port, which I've determined to be used with the X/Y/Z-DIAG pins of the TMC2209 drivers. Hence, if you some day decide to use the stall detection feature of the SMUFF for Selector/Feeder (which has been sitting there and waiting for free input pins) you'll be able to. Read more about it down below in "Meanwhile in the test lab...".

What I haven't been able to test yet is the SKR E3 RRF board (which comes with a STM32F407 MCU).

I've also already updated some of the documentation pages in here, to reflect the changes. More to come after the release of V3, which will happen very soon. 

I've updated the Base-Left STL file within the Github repository. This one has got additional blind holes to take M5 heat-set inserts (9.5 mm in length) as an alternative to the M5 captive nuts, holding the threaded rods (see picture). 

You're now able to decide which one you want to use. The length of the threaded rods stays the same. If you're  going for the inserts, screw the rods all the way in and secure them in place by using a drop of Loctite.

I'm currently working on the next iteration of the SMuFF firmware, which is going to become version 3.0.

The change in the major version number might tell you that there's a bit more to it than just bug fixes or new features. In fact, I'm swapping out the LeafLabs Maple framework for the STM32Duino framework. This "new" framework is mainly managed by  a team from STM and it's focusing on bringing all the various STM32 MCUs to the Arduino platform.
This is a huge deal, because development of the Maple framework has been abandoned and only supports the STM32F103 MCU (and partially the STM32F4), whereas new controller boards in the 3D printing area come with newer, much more sophisticated MCUs from STM. The legitimate successor of the SKR E3 V2.0 for example is the SKR E3 V3.0, which is equipped with a STM32G0B1 MCU and is the one that I've picked to be supported next as the SMuFF controller. 

I've recently published the base module for the Filament-Cutter.
This STEP file comes in handy if you're about to integrate the Filament-Cutter in your 3D printer using a specific hotend.

You'll only need to transform the Filament-Cutter-Base part (the transparent piece in the picture on the left) by adding some mounting points and joining it with the design of your hotend.
Everything else, such as the Punch or Servo-Mount/Servo-Horn parts are supposed to stay as they are, though you'll need those to check the placement/fit of the Cutter as a whole.

Get it here on Thangs.

If you integrate the Filament-Cutter into the hotend of your printer, please share your creation on Thangs / Thingiverse and let me know if you did.  

I've recently published another (rather old) design for a Filament-Cutter integration on a E3D-V6 (or clone) for Creality 3D printers (i.e. Ender-3, Cr-10) on Thangs as a STEP file (mainly for modders) but also with the STL files contained in the ZIP file, if you'd like just to print one yourself.

Although the first published model did meet the needs for the Filament-Cutter, shortly after I published a revised version with an improved cable management (which you see in the picture to the left). 

So, please make sure you have downloaded the 2nd revision, because routing wires and cables on the 1st revision might by a bit of a pain (especially the ones for heater cartridge and thermistor).

The 2nd revision also got a stiffer mount for the inductive probe / BL-Touch and two additional heat set inserts in the front piece of the E3D-V6 mount, in case you're heading for a different part cooling fan solution. I've also added a Cutter-Base STL file which takes only the M6 fitting and doesn't need the Splitter adapter, which is easier to print in case you're only going for the standard E3D-V6 bowden style solution.

Just in case you were wondering: Since the Filament-Cutter is designed to be detachable (mainly for maintenance purposes), it can be left out completely and the whole mount can be used on a non-SMuFF Creality 3D printer as well.

Actually, it's not that new but I'd like to share this information anyway.

It's the SY8205, a 5V Buck converter which claims to be able of delivering up to 5A of current, and is therefore suitable for all the servos, NeoPixels and stuff you may use on your SMuFF. Hence, it can easily replace the LM2596S. 

In comparison, this module has two advantages:

• it's already preset to +5V

• it comes with a plated through hole area, which takes a 6x4 pin header

Those pin headers can be used to connect up to 6 servos directly. The pinout  (G, 5V, S) comes in the correct order for a servo connector. The signal (S) wire has two separate connection points: One goes to the servo whereas the second one is supposed to be the input, which comes from the SMuFF. Hence, only one signal wire per servo/device needs to be routed from the SMuFF to this little fellow. This makes makes your wiring more professional and tidy. 

For other electronics, such as the NeoPixels, you'd have to reorder the wiring on the other end (at the NeoPixel strip for instance). If you need static +5V and GND only, a 2 pin header / Dupont connector is sufficient. 

If you're looking for this board, AliExpress or Amazon are supposed to have plenty of them.

Here's my version of the Filament-Cutter for the MicroSwiss Direct Drive Extruder for Ender-3
Similar to the Orbiter Extruder, the Cutter sits between Extruder and hotend and thus helps to reduce the waste on the cut off filament.

Be aware that this is a STEP file only. If you want to print it, you'll need to export at least the Cutter-Base and the 2nd endstop mount.

Download it here on Thangs.

Since some users have reported having problems connecting to the Duet/RRF via the serial interface, I've decided to revive the SMuFF-Ifc project in a simpler and also cheaper version.

This is based on the WEMOS D1 mini and acts more or less as a signal amplifier between the Duet/RRF and the SMuFF controller boards.

If you're connecting the SMuFF to a Duet/RRF controller, I highly recommend using this device. It's easy to set up and will save you some headaches.

All information you need to know about this new little gadget can be found on my Github repository.

Update

Meanwhile I've added the ESP32 option to the firmware published and now you can compile the firmware for both devices.
The ESP32 has the advantage of interconnecting more devices, such as SmuFF, Duet/RRF, PanelDue and SMuFF-WI (using Bluetooth). This feature makes it really a powerful tool.

STEP files for the housings are included in the Github repository or  on Thangs.

I designed a new housing for the SKR E3 series controller.

This housing takes the SKR E3 controller (-DIP/V2.0/V1.2), the Velleman VMA 400 or Elegoo 4 relay board, the LM2596 or SY8205 buck converter and a display (DIY OLED, LeoNerd's OLED Module or FYSETC 12864 Minipanel). 

The new shape makes it visually less bulky than the old one and allows you a much more convenient handling while wiring the board up. You can use it either standing on the desk (near the printer/SMuFF) or mounted to the printers frame (attached to some gooseneck mount).

The STEP file, containing the housing, two top lids, three display lids and a couple of template lids can be found here on Thangs*.

Please notice: The display lid has to be printed flat and then bent over to meet the upper angle.
Right after printing, let the bed cool down first then remove the lid from the bed. Put it back on the bed in printing orientation and heat up the bed to 5-10 °C above the glass temperature of the material (60-70 °C for PLA, for example). Let it sit for about 10 minutes then carefully bend the lower (bigger) part into position. 

* No, they didn't sponsor me. It's just because I personally think it's time to move from Thingiverse somewhere else. 

Here's just a short testing video...

This video shows the handover from the SMuFF to a (Bondtech) Direct Drive Extruder.

As you can see, the Bondtech DDE has got a nice (top-) cover, which not only suits it well but also integrates the 2nd endstop, which allows the SMuFF to determine when the DDE has gotten the filament.

Both Extruders are being controlled by the SMuFF simultaneously. The DDE in this scenario is connected to the Shared Stepper relay. This allows the SMuFF to control the DDE while loading/unloading and return the control to the printer, once the tool change has finished by switching the relay back.

Looks promising so far but it'll need a bit of fine tuning on the firmware side since at a certain point,  both extruder motors have to run at the same time and the same speed.

Here's now a detailed "How to"  on setting up a Direct Drive Extruder in conjunction with the SMuFF.

The according firmware (V2.30) will be released soon.

Therefore I've created a new IR sensor mount which is supposed to overcome this potential issue.

As you may spot in the picture to the left, the filament never leaves the bowden tube. Instead, the whole bowden tube is being guided through the IR sensor and hence it reduces the potential of failure.

Since the outer diameter of the bowden tube (4 mm) is 1 mm more than the  recess of the IR sensor, we have to cut out a piece of the bowden tube in order to make it fit. That is a pretty delicate task, since you don't want take away too much material off of your bowden tube or even cut it in half.

That's why I also designed a cutting template (3rd picture) which will ensure that the  incision sits at the right position and doesn't go deeper than it has to. 

The mount itself will keep the IR sensor, as well as the bowden tube in a determined position, so that the sensor will trigger reliably (which is only the case if the filament is guided correctly at the height of the IR LED/Receiver).

I know:  Usually it's not the best idea guiding filament directly through the sensor because some filaments are know to be "IR-Translucent" (means: the sensor won't be able to trigger anything). Hence, I'm currently testing this setup with different materials for any shortcomings.

Once I'm convinced that this solution is usable, I will publish this design on Thingiverse. 

In order to be able to mount the cutter as close as possible to the nozzle, I designed a "spacer part" that mounts on the X-Gantry, which then will hold the hotend, the cutter the fan shroud and additionally other  stuff as well. Unfortunately, this spacer makes the nozzle move by 17 mm in Y direction, so you may have to adjust your print bed. However, it also integrates a strain relieve for the hotend cables. 

In order to connect hotend and cutter, you will need a 23 mm long PTFE tube (MicroSwiss hotend). The cutter simply slides over the PTFE tube and is being held in place by a dovetail and a latch securing the dovetail. 

Since the MicroSwiss All-Metal hotend comes with a collet in contrast to the stock hotend, you may have to replace the fitting on the stock hotend with something "collet-like" in order to use it.

However, I'd rather recommend using an All-Metal hotend for multi material printing.

So far, I highly recommend the Filament-Cutter since it makes tool changes (and your life) so much easier. I've printed the 5 color 3D Benchy for testing and it didn't fail once (take into account, that this Benchy does at least 3 tool changes per layer, once the lower part of the hull is printed).

You can download the STLs aswell as the STEP files  from Thingiverse.

I will add a modded version for the 5-way splitter sometime in the future.

You may recognize the 5-way splitter from the "Background page". It indeed is mostly the same, except, the outlet has got a thread, so you can easily attach it to the cutter.

This tool is part of the idea I had a long time ago in order to reduce the tool changing times. It's as simple as that: The shorter the path, the faster tool changes can be handled.

Due to the fact that the filament cutter already "steals" quite some precious print height, I didn't want to stress that "steal" more than necessary. So I came up with combining the two items into one. Combined, this will reduce your available print height for about 90 mm - 110 mm, which - I guess - is negligible for most of the MMU prints. Without the combination of both, it would have been about 40-50 mm more.

I also got rid of the recess which was meant for an additional filament sensor, so it's somewhat easier to print. 

Beside this, the cutter works the same way as in the first published version.

You can download the STLs from Thingiverse.

In the picture on the left you see a size comparison. In the upper left corner the genuine Velleman / Adafruit, in the lower right corner the new relay board. The buck converter in the upper right corner is being used as a size reference. As you can see, it's barely bigger than the buck converter (same width but a bit longer 57 x 21 mm).

Hence this relay board will perfectly fit in the existing cases where the 2nd spare buck converter was meant to sit (see 2nd picture).

The schematic for this relay board can be found here.

Since this board indeed is a bit fiddly to wire up manually (I can tell for sure...) I've also created a PCB for it, as shown in the 3rd picture. If you'd like to get such a PCB, head over to PCBWay where I've put my PCB designs online, ready for order.

The PCB uses standard (SMT) components and is nicely labeled just to make sure you won't mix up the connectors when assembling.

Be aware that this relay board uses smaller Omron relays and therefore they're not suited for switching voltages where the current exceeds 2A (2.5A max.). Though, its ought to be sufficient for most of the NEMA17 stepper motors around, which usually don't go over 2A.

For good measure, just as the Velleman / Adafruit board does, this board also uses a galvanic isolation (optocoupler) on the input side to protect the MCU. 

In order to connect it to the SMuFF you'll need to provide +3.3V, +5V, GND and the switching signal on J1 (the leftmost JST XH connector).

Please notice: In case you'd like to utilize this relay board with something else than the SMuFF, please keep in mind that this board switches all 4 inputs simultaneously.

The main thought behind this tool is the fact, that there's still one major culprit in the multimaterial printing game: The bulged filament. 

Depending on the type and brand of material used, it tends to bulging - sometimes more, sometimes less. This may cause the filament to get stuck in the bowden tube while a tool change is ongoing.
In the worst case, even the mighty Bondtech gears may not be able push/pull the filament through.

Using a cutter somewhere near the hotend could solve this problem easily. Instead of retracting the bulged filament, simply cut it of and get a nice and clean shaped tip.

My goal was to create something reliable though small and lightweight, in order not to add more heavy load to the (moving) hotend.
Although a lighter version would have been using a small servo (a.k.a micro servo), servos this size unfortunately don't have enough power to cut filaments reliably.

The picture on the left shows the basic principle of the cutter (first version). In the video below you'll see my very first attempt building one.

The published version has got some improvements of the printed parts  in terms of strength and stability and also the blade angle has changed in order to get cleaner cuts and avoid jamming.

So far I've tested it with these materials: PLA, PETG, HIPS, ABS, FLEX, PC, PA and PA-CF. Even the Carbon Fiber reinforced PA cuts with ease (though, this material will presumably wear out the blade pretty quick).

Please notice: This cutter has been integrated in the SMuFF firmware 2.17 (see README.md).