Filament Not Sticking and Spraying Everywhere

Attached photo sums up the problem pretty well. The print starts off great, then after a short period the filament stops sticking and creates a giant mess if it continues to print. Smaller prints seem fine, its longer/larger prints that this happens for. However, even with the parts that print well the filament doesnt seem to adhere to itself very well. Also, if the print keeps going for a while there is a sharp jerking/popping noise that comes from the extruder motor, it happens about every 5 seconds or so, however when I check for grinding there is none present. I feel like I've tried changing just about every setting I can think of but nothing seems to help, has anyone seen this before? Its on a BCN3D Sigma R16 printer.

I've had this problem in the past and usually can attribute it to filament that's jammed up debris in the nozzle. Sometimes a nylon cleaning will take care of it.

You've "changed every setting" but that doesn't tell us much. After you've cleaned the nozzle you can start afresh, perhaps by raising the temperature by five degrees.

Have you checked for free movement in the bowden tube? I've moved the extruders to the outside rear, eliminating the pull-side tubing and really cutting back on the noise.

Do you have the stock stepper motor assemblies or have you upgraded to Bondtech?

Also, some filament feeds better than others. If you are using PLA, is it dry or has it been out exposed to humidity for an extended period?

Thanks for the response, I did do the nylon cleaning but its jammed up a number of times since then so I'll give it another go.

I did try adjusting the temp settings as well, I even printed a temp tower to try and find the optimal setting (which printed fine because it was relatively small). Other things include, changing the nozzle (same size and other sizes), changing the flow settings, slowing everything way down (also speeding it up), it looked like retraction wasn't working great so I've changed that as well, I've tried printing on the other side using a separate motor, I've updated Cura and the firmware on the machine to the latest, tired brand new PLA and old PLA, as well as some higher grade PLAs like PLA/PHA and Tough PLA, I've there are more as well but I'm fine with folks suggesting even basic things, there certainly could be something obvious I've missed.

Interesting ideas about moving the motors, so far I have not made any changes to the stock parts of the machine. My thought was that, while there might be ways to make it better, the machine from the factory should work as is. It is 5 years old at this point, could there be something worn out that should be replaced? Has anyone had a temperature sensor on the hot end go bad? Im wondering if maybe its not able to stay hot enough and it stops adhering after a while because its cooled down, Im not sure how I would even check that though. The temperatures read normal during the whole print and I've tried autotuning the hot ends multiple times which Im told should help stabilize the temperature.

Is it the entire print that is coming loose from the bed? I used to be able to print on the clean glass, but found that it was too risky and shifted to using purple glue stick, which works wonders.

It looked in the photo as if you were having underextrusion, which is the problem I'm having as of late, but haven't had a chance to attack it.

You can test your extrusion "wear" by popping out the bowden tube at the hot end and see if a 100 mm extrusion command gives you 100 mm of filament from the tube. Now that I've typed that, I think I'll do the same test and also clean the debris from the drive. There's a lot of filament dust in the drive area.

Regarding the hot end. I've had to jack my temps up about 5 degrees from factory recommendations as I think the presented temperatures tend not to match well, but I've had good luck with that.

This stuff can be frustrating, I know. I had a recurring problem with getting the bed level. Printing on the left side would be great, using the left extruder. As the left extruder moved to the right side, the bed was too high and it blocked the nozzle. No amount of leveling sequence solved it and it simply went away on its own. That makes no sense at all!