Fixing a 3d printer

A thing I can do for you is 3d printing: we can design something (starting from mechanical specifications) or translate a paper drawing in a 3d file (an .stl file or another CAD format). Sometimes you have to print things in order to see if everything is OK, and unfortunately funny accidents happen. Here’s how I fixed a problem with the nozzle of a Creality Ender III printer.

Assessing the accident

Well, a picture tells more than words, they say:

A print gone bad…

That happened in an Ender3 printer during an overnight print. What I think is that during night the nozzle got obstructed, and the PLA made somehow its way out. Poor adhesion on the plate could have played a role in this thing (the piece was found attached to the nozzle).
The cooling vent was also damaged, as seen here:

The damaged vent

How to fix this thing? We will start replacing the nozzle.

Replacing nozzle

First we need a new nozzle. Release the two screws un the front of the extruding head, the two screws that hold the head to the X-axis sledge and the two screws that hold the nozzle head to the case. Keep the screws: in the nozzle kit you won’t find new ones.
If for any reason you need to remove the sledge it is easy to make a mistake when you put it back in place: the lower bolt is mounted in opposite direcion respect the upper two ones (the sequence is bolt, spacer, sledge plate, hex dice). If mounting the sledge back you notice that its contact to the X-axis bar is not tight, you need to turn the hexagonal dice on the rear of the sledge plate:

The hex dice to tight nozzle head

The dice has an eccentric hole that moves the lower wheel up or down of a couple of millimeters, making possible to tight it back.
Now, before detaching the nozzle you need to detach the wires that link it to the motherboard:

sensor terminals
head terminals

You also need to cut the cable ties and the black tape that hold the socket that keeps the wires together. Once wires are released you can pull the old nozzle out, so it is completely separated.

To replace the nozzle, you need to push the wires back into the socket, till they exit the socket on the motherboard side and link them back to the motherboard. The red wires are linked to the green terminals, while the white wires are linked through the white connectors (that can be inserted in one way only). Now you need to turn the printer on its side, and put some tape around the socket to protect it from the sharp edges of the aluminium structures around them:

Put some new cable ties where you removed them. Finished!

Fixing the vent

To fix the vent and prevent future damage of the some kind, you need to assess that the internal sructure of the vent is free and smooth (and I was lucky, it was, if you’re not you can print a new vent piece with another printer…) and to put a small layer of a protective paint on the vent to prevent adhesion. You can easily find products that are both anti-adhesion ad heat protective. This is the result:

Painted vent

If the vent is also internally damaged, you should suspect a fan failure. That was not the case here.

Back on line

Our nozzle head is now back in its place:

The head is back in its place

The replacement nozzle is little larger than the previous one, and we also replaced the printer bed with a glass one (that is higher), so we need to move the Z offset. To see if that is your case turn on the printer and home the head. If you notice that the tip of the nozzle is not at the height it should be, turn off the printer (or disable steppers), move up the extruder head and lift a little the Z-offset sensor on the left side of the printer (releasing the bolts):

Z axis offset

Home the head and see if everything is ok (if is not, just repeat).
That’s it, print something for a test:

And, if successful, you’re back on line!