BIGTREETECH DIRECT SFS Smart Filament Sensor, 1.75mm PLA Filament Runout / Break Detection Sensor Compatible with SKR Mini E3 V2.0, SKR Mini E3 V3.0, Octopus V1.1 Control Board

This little guy is actually amazing if you know how to make it work. You will not get any documentation out of the box...nothing. Fortunately internet has got a lot of useful information on how to install and compile the firmware...Yes...you have to compile your own firmware. It is actually pretty easy. There are some YouTube videos and BIGTREETECH github site also has many info and troubleshooting. With that said, let me explain to you how I made it work flawlessly. First let me tell you my setup: I have a BTT SKR Mini E3 V2 and TFT35 E3 V3 attached to my printer. This BTT SFS can be connected to either the mainboard or the touch screen display (TFT35). If you see the back of TFT35 you will see a port call "FIL-DET", basically short for filament detection. I have my SFS connected to the TFT35 because I wanted to make use of the touch screen mode. Note that if you do wire the SFS to SKR (mainboard) you are only limited to use the Marlin Mode on your TFT35. So if you have similar setup as mine and want to use the touch screen make sure to connect your SFS to back of the TFT35. The connector wire that comes with the SFS is long enough to route all the way to Extruder motor through the cable braid from main board. Now I followed 3D Printscape on YouTube for step by step installation and firmware compilation. He did a great job explaining it. Once I updated my firmware I noticed that the sensor was not working...got a little nervous at first but I managed to find a solution. I had to disable/comment out the "define LIN_ADVANCE" in configuration_adv.h file. I re-build the firmware and uploaded to my SKR and it BOOM sensor started working like a charm. It stops the printer as soon as it detects the absence of the filament as well as if the filament does not get pushed through. Super helpful when you are doing long 3D printers and overnight prints. Highly recommend for anyone looking for a good filament detection sensor.

This is such a huge improvement over microswitch and optical gate based run out sensors that come with most printers it's almost funny. It detects if you're out of filament, it detects jams, it detects skipping, it's highly hackable, it takes print reliability to a whole different level. I've got mine wired into a raspberry pi running an Octoprint instance, and it's essentially put an end to the days where I needed to carefully weigh and track my filament to work out if a print was doable or not. Now whenever filament runs out it just automatically sets up a material change.Only downside I can point to is the fact that it is a lot more complicated to install and configure. There really isn't a great mounting solution here (though you can track down printable ones, of course.) And it took about half a dozen false positives before I learned how to dial everything in right and what kind of margins were acceptable. But I've made back all that time spent tinkering with it on every print it's saved.

Picked this sensor up to save on time & money while printing. Horrible feeling when you have a long print only to lose your effort because the spool was short a few grams of material. Also, now, i can use all those short spools and not waste material as well. :)Anyways setting up the sensor was a bit of a headache. There is little documentation available form BigTreeTech and while I found plenty of complaints on reddit and Github. It seems no one follows up with a fix or a solution. It's unclear to me if people simply give up or if they just don't think to follow up on their solution.So following a couple of guides on Youtube, i was able to get this sensor installed on my Ender 3 Pro (SKR mini e3 v2 mainboard). This requires you to update your firmware. There's a few precompiled versions out there, but it's been my experience recently that you're better off compiling your own frimware. Especially if your printer has been modded in any way, which mine has.So the issue was I'd start a print, and immediately after putting down the purge line, the printer would trigger a filament change and park itself and wait for me to swap out filament. During the firmware setup, I noticed that the "FILAMENT_RUNOUT_DISTANCE_MM" line was set to a distance of 7mm by default. I increased this value several times, as high as 125mm, with absolutely no change in behavior. I spent a few days scouring reddit and Youtube looking for a solution and found a post where someone entered a command through a terminal of M412 which will return the set filament runout distance for your printer. Mine was showing ZERO as the value. This in spite of me specifically targeting this value several times.So using the terminal through Octoprint, I entered: "M412 D25" to change my filmanet runout distance from zero to 25. Followed that up with another M412 to verify the change had taken place. That fixed my issue. I went ahead and stored the settings on the printer using the "STORE SETTINGS" funciton from the printer and haven't had an issue since.The sensor would receive a 5 star rating otherwise, but the lack of documentation and the difficultly in finding a solution dropped the rating down to 3 stars.

I don't leave reviews often so please take what I am saying seriously. The installation on the BTT Octopus 1.1 was so easy and this thing has saved me so many times I cannot count anymore. Every time it paused the print it was because of runout or jam (especially a jam!!) no false positives. I have a Voron 2.4r2 350 and it has been an educational experience, to say the least but I cannot say it enough this thing will save you so many headaches. Just remember if it is telling you there is an issue listen and troubleshoot. It is so cheap the amount of filament you save is crazy so I will definitely buy another if this fails (6 months no issues so far will update when it fails)

Got tired of print jobs failing due to tangled filament. This has a motion sensor that will detect when the filament stops moving, not just runs out like the others. Combined with a plugin for octoprint, this works relatively well. A bit more of a pain to load filament but the peace of mind makes it worth the effort. I also didn't install this as intended. Printed a bracket off thingiverse that I liked and so far it's working perfect.