Cleanup after a large Blob
Was printing and ended up with a big Blob and spaghetti. Looks like the Blob got pressed into the printhead and nothing is printing now. My first question - what can I do to get the printhead to the top vertical position?
I was printing PLA when this happened. I later did a small PETG print and it worked, but got a Blob of the PLA on it. Tried PLA again and no good. Tried printing the PRUSA test pattern and i just get a small PLA deposit periodically. Can send pics after I get the printhead away from the bed.
Looking for hints on how to cleanup the bottom of the printhead.
Thanks for any suggestions,
Tom Z
RE: Cleanup after a large Blob
Was printing and ended up with a big Blob and spaghetti. Looks like the Blob got pressed into the printhead and nothing is printing now. My first question - what can I do to get the printhead to the top vertical position?
...
Looking for hints on how to cleanup the bottom of the printhead.
You mean the nozzle is covered in a blob from a previous print? Manually raise the Z axis using the LCD and dial interface. It's under Settings -> Move Axis -> Move Z and move slowly to not crash into the bed. Preheat the nozzle to 210C using the same menus. Carefully peel the blob away using your fingers. Do not damage the thermistor or heater wires. Use a brass brush to gently clean the nozzle surface. Use the acupuncture needle included in your kit to clear the nozzle hole. If it's still clogged you might need to do a cold-pull.
https://help.prusa3d.com/article/cold-pull-mk3s-mk2-5s_2075
If all that fails you have to disassemble and clean the nozzle and heatbreak separately. Big job. Avoid if possible.
RE: Cleanup after a large Blob
Thanks very much. I have managed to get the blob off, and will follow your other suggestions. Have to go find a brass bristle brush.Hope I don't have to take it apart but I did build it, so should be able to rebuild it
This all started with an adhesion problem. All had been printing well previously, so that was a surprise
Tom
RE:
Hi Tom,
for your adhesion issue,
You could try what I do.
I take my build plate to the sink, and wash it vigorously with plain dish soap, hot water and a previously unused dish sponge, (I keep a dish sponge on one side, specifically for cleaning build plates)
then I dry the build plate immediately with hot plain water, and dry immediately with Plain Paper towels.
Only handle the build plate by the edges and you should get great adhesion. 
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Cleanup after a large Blob
Joan,
I will give that a try. I do have some small deposits that need something more than elbow grease for removal.
When I first built my machine, I am pretty sure I used a Post from you on getting the calibration set and adhesion working. Thanks for your very helpful comments and ideas
Tom
RE: Cleanup after a large Blob
Cheers Tom,
IPA can loosen particles on build plates
Making them easier to remove
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Cleanup after a large Blob
progress but not done yet. Cleaned a ton of PLA from around the printhead. Cleaned the nozzle and thought I was in good shape. When I load filament, it seems to flow smoothly. I ran the Zcal. But when I try to print, almost nothing is deposited. Do I need to go back to assembly and redo the probe positioning? That is all I can think of doing at this point. Either the head is hitting the print sheet or the Z is way off .... or something else I am totally missing.
Tom
RE: Cleanup after a large Blob
Make sure there is no filament melted in the gap between the heat block, and the heatsink.
filament in this gap short circuits the heat break, and leads to Heat Creep by transferring heat directly into the heatsink above the heatbreak
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Cleanup after a large Blob
Remember to turn the power off while brushing. It’s easy for the brass bristles to short out the power at the heater. This can have lasting consequences!
RE: Cleanup after a large Blob
Thanks for the additional input. Thought I had removed all of the debris BUT now I see there is still a glob on the side of the nozzle/head where the two red-insulated wires are connected. I do now have freely flowing PLA coming from the nozzle when loading the filament.
Tom
RE: Cleanup after a large Blob
Joan - I think you may have nailed this problem. I went back and looked at the build instructions and photos to better understand the construction of the hotend. There is a large amount of solidified PLA on one side, and it is obscuring the "gap." It certainly seems like that would have to be disrupting the heat profile.
I will spend some time cleaning up the remainder when I get home from our Christmas visits.
Tom
RE: Cleanup after a large Blob
Tom - I am surprised to hear that there may be power accessible on the outside of the hotend. So must I heat it to soften the PLA, turn off power, then try to scrape it before it cools down?
RE: Cleanup after a large Blob
@Tom
the image above shows a heater for a Mk3 series printer the wires are high temperature fibre glass insulated flexible wire, however the wires coming out of the heater bulb are in insulated single core wires,
Prusa use crimps to join the flexible wires to the single core wires, and they slide larger diameter high temperature sleeving over the joints
However the heater wires on a mk3 series printer, are bent at 90 degrees where they leave the stainless steel bulb casing, and there is a small chance of a gap exposing the wires at the bend,
there is no risk of you touching the wires with your fingers, however brass brush bristles may find their way under the insulation,
If the bristles short your heater power it is likely that a fuse will blow.
If the brass brush is used vigorously, it is possible to damage the thermistor insulation, If you happen to short Heater power to thermistor circuit, then your controller could be toast...
Please be careful out there!
Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Cleanup after a large Blob
More progress - but still not done. Here are pics of the Glob initially and after my first attempt to clean it all out.
After initial cleaning, I could see that there was still PLA on one side and on TOP of the hotend box. I removed both fans so I could readily access the entire area and cleaned out the remainder. I preheated to PLA temps, turned off the Printer, and scraped the PLA from the printhead area. I used tools from a cheap Gun Cleaning kit sold at WalMart. The other thing I used that was a huge help, is a wooden coffee stirrer. That was flat so it reached in between the heatsink and the hotbox, and the heat was no problem. I was VERY careful around the thermistor wires, as suggested here.
A huge improvement was the result, but still having problems printing. I might now be back to the normal adhesion and calibration problems that I faced upon building the machine. Filament seems to be flowing freely now, but I do wonder if I am going to have to use a Cold Pull to clean out any more residue.
I sure am glad I built this printer, which made me more willing to jump in and disassemble as needed to clean out the mess.
Thanks for all the help.
Tom