TPU started jamming suddenly
I have two machines, one MK4 and one MK4 that was upgraded from a 3+. I have been printing (manufacturing) identical units on both printers with Flexfill 98 and have had minimal problems. Suddenly, the upgraded printer always jams on the first layer or second. I have tested the printer, dried the filament and looked over the machine without finding any obvious defects. It is the typical jam, clicking and no more filament is extruded. I printed a large PLA project to test it and it worked perfectly. The only thing I've noticed is that when I load filament, sometimes instead of coming straight out of the bottom of the nozzle it comes out at an angle to the nozzle tip. Ideas?
Joe
RE:
Just a guess but maybe partly blocked nozzle. Try swapping the nozzles on the two machines and see if the problem goes with the nozzle or stays in the same place.
If it is burn out the blockage with a blow torch or cold pull.
RE: TPU started jamming suddenly
Thanks, I think you may be right. I just ordered new nozzles.
Joe
RE: TPU started jamming suddenly
Don't throw out the old ones, you can normally clean them out by heating them up with a blow torch or on a gas cooker
RE: TPU started jamming suddenly
I do have a torch but have never attempted this. Do I just hold it vertically and heat with the torch? Can I damage the nozzle doing this? In other words, how careful do I have to be with the heat? Thanks,
Joe
RE: TPU started jamming suddenly
Pretty much just hold it in the flame using pliers. I don't let it get too hot so of it starts going red take it out and let it cool or move to a different part of the nozzle. You might get flames or drips out of the nozzle.
RE: TPU started jamming suddenly
What does the "jam" look like? Is the filament jamming in the nozzle, or is it bunching up just below the extruder gear? Or something else...
"Jamming" on the first layer can be a result of the layer height being low and the squish being high, resulting in a large pressure being needed to extrude. With a flexible that can lead to the extruder pushing more filament than can be moved down the tube and thus a bulging of the filament just below the gear and a clog. The solutions for that type of problem include higher temperatures, slower speed on the first layer, and higher first layer height.
RE: TPU started jamming suddenly
I have been "manufacturing" identical parts on two machines with minimal problems until now. One MK4 and one 3+ that was upgraded to a 4. Anyway, the jam looks a lot like the jams that were more common on the 3+ when the heat built up around the idler gear feeding the filament resulting in the filament being too soft going through the gearing. It just starts clicking and no more filament is pushed through the nozzle. I am using the exact same file for both machines. I removed the nozzle and heated it with a torch with no improvement. I will replace the nozzle but I don't have faith that this will fix the problem.
Joe
RE: TPU started jamming suddenly
Did you open the extruder gate up and look inside? I suspect that you will see a little loop of filament where it should be straight. Unload the filament and see if there are any kinks in it that would indicate the problem that I described.
It is not likely to be a nozzle problem, but if it is then a 'cold-pull' is a good idea to try before replacing the nozzle or torching it.
RE: TPU started jamming suddenly
I'll take a look tomorrow. If that is the problem, what is the solution?
RE: TPU started jamming suddenly
What does the "jam" look like? Is the filament jamming in the nozzle, or is it bunching up just below the extruder gear? Or something else...
"Jamming" on the first layer can be a result of the layer height being low and the squish being high, resulting in a large pressure being needed to extrude. With a flexible that can lead to the extruder pushing more filament than can be moved down the tube and thus a bulging of the filament just below the gear and a clog. The solutions for that type of problem include higher temperatures, slower speed on the first layer, and higher first layer height.
RE: TPU started jamming suddenly
Michael, thanks for your help. I received the new nozzle and installed it. The printer completed a 5 hour print without incident. I'm not sure what the recommended interval for nozzle changes is, but this one has many hundreds of hours of time printing. In the future, I will have a few nozzles ready to go.
Joe