Nozzle Clog Detection
I'm working on a college team to design a mod that detecting nozzle clogs, and is focused on hobby printers using the MK3s. The mod would automatically stop the print. What kind of things would be important to people who would potentially use this mod? What kind of resources would people have to make it themselves? What would you be willing to spend making it yourself? And any general comments on this kind of mod if you have experience with doing stuff yourself.
Updates to come as we progress.
RE: Nozzle Clog Detection
The original MK3 had a laser motion sensor to detect filament stalls. The primary issue was the sensor is designed to see metal, not filament, and some filaments were invisible to the sensor so it would fail and stop prints for no reason.
There is a user mod to add a metallic bearing that rolls on the filament and presents a solid surface to the sensor. This mod to a MK3 accomplishes what you are trying to do.
RE: Nozzle Clog Detection
The filament sensor in MK3S detects filament run out. However, it doesn't detect a clogged nozzle. When a nozzle gets clogged or filament stuck at the beginning of PTFE tube, the sensor will keep sensing the filament in and will not trigger.
One way I see to detect both filament run out and stuck filament is using a roller connected to a potentiometer. As the filament feeds, it will turn the roller+potentiometer. The FW will compare this movement (In/Out/Stop) to the Extruder movement. It should trigger if there is a difference. Basically, a feedback system on the filament movement.
RE: Nozzle Clog Detection
It would be worth measuring the stall current of the extruder motor when there is a nozzle clog / jam. Since the motor will continue to push filament in, right before the gear skipping (clicking noise) one should see a slightly increase in the motor current draw before it drops again and repeats the process. I am not sure if the clogged nozzle would be enough to reach the stall current, but there would definitely be a current spike. The question is "how much". An oscilloscope might come handy here.
RE: Nozzle Clog Detection
you would need a rotary encoder ( continuous rotation) not a pot
RE: Nozzle Clog Detection
@moraes-mauricio
I know this is an old topic, but i was just kind of brainstorming and thought about how AI is being used for things like spaghetti detective to determine failed prints visually.What if a simple microphone or cheap and sensitive accelerometer could be used and train the AI to recognize the extruder skipping noise or vibration "signature" of the sensor? I know virtually nothing in terms of how feasible something like this might be, just thought i'd throw the idea out there for smarter people than me to ponder lol.. I also like the idea of monitoring and referencing the current draw of extruder motor which would surely throw out a clear anomaly for some clever software to recognize and either shut down the print entirely or send gcode to lift z, move out of the way and pause the print ant notify you to come take care of it .. then if its late in the print, theres a chance you could clear the jam and salvage the print. .
I have something along the same lines set up for my air filter using a smart plug with power monitoring to automatically shut it off if the current goes higher than normal basically letting me know the filter is clogged when there's a spike in the fan's power draw avoiding a burned out motor.
RE: Nozzle Clog Detection
For quality control, a miniature sensor mounted near the orifice of a nozzle can optically detect a spray pattern emerging from the spray tip and send a “spray present” signal to the controller. Unconfirmed spray cycles – often the result of clogging – can activate alarms or stop production.
RE: Nozzle Clog Detection
Here's what I'm thinking...
I have a run-out detector on my 3d printer that has 3 pins (+V, Gnd, Signal). Doesn't check for stalls or clogs, but makes the printer pause when the filament runs out (i.e. probably breaks the normally closed circuit between the Ground and the Signal wire).
I printed a filament guide that has a roller that guides the filament from the spool at the top of the frame to the top of the run-out detector. https://www.thingiverse.com/thing:4206029
The filament is always in contact with the little wheel and is a pretty good visual reference for if it is feeding or not.
I've had quite the few clogged jobs or when there was a not in the filament and caused the filament to stop being applied even though the print head continues onward. I too had the thought if there was some way to track of the filament guide roller vs. the extruder wheel then it could be able to track if the nozzle is clogged or filament spool is jammed.
Looked at rotary encoders but they seem to be quite expensive. Then, I came across a cheap little magnetic encoder that I think will fit the bill. AS5600. Youtube Example. Example Amazon link. It's about the size of a stamp, cheap, and comes with a special magnet that can easily be attached to a roller or spindle on an extruder shaft to track rotation, and all wrapped up with a mini microcontroller like the Seeed XIAO or similar.
So my plan is to have (2) magnetic encoders, one mini microcontroller, and track the motion of the extruder spindle vs. the motion of the guide roller wheel all tied in to the same place as the run-0ut sensor, (although to be honest, it could actually replace the run-out sensor...). I'd figure out the normal ratio of extruder spindle to guide roller rotations, and if the 15-second average is outside specified variance then send a signal similar to what the run-out sensor sends which would pause the print until I can get to it and resolve the issue.
I've got parts coming from Amazon. Will keep you updated.