jitsbuild-failure-conditions [Bukobot 3D Printer Instructions & Docs]

====== Failure conditions to watch out for ======

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There are many things that can go wrong with a device like this.  Things can get too hot, or too cold;  things can move incorrectly, or not at all;  things can move too far and jam against things they should never touch.

If you ever observe any of the following conditions, don't let it sit there and burn itself up or grind itself to pieces.  Press the small blue reset button on the Azteeg controller, or power down the printer.

Before you first power up the printer, and after every time you plug anything back into the Azteeg controller, the first things you should do is double check, no, //triple// check that:

  * the motor wires are plugged into the correct connectors
  * the endstop wires are plugged into the correct connectors
  * the thermistor wires are plugged into the correct connectors
  * the extruder heater wire(s) and the heated bed heater wires (if any) are connected to the correct terminals

If you have any one of these connectors in the wrong place, your printer //will go crazy//.

==== Things getting too hot, or not hot enough ====

As mentioned above, it is critical that the thermistors and heaters are wired correctly, otherwise the heaters will not work properly.  Things might stay cold, or get much too hot and cause damage.

The thermistor connectors on the Azteeg controller are marked strangely.  Check the [[bukobot-assembly-documentation|Azteeg documentation]].

An infrared thermometer is a handy tool for checking temperatures.  These can be found for as little as US$20.  Some of these have a laser pointer to help you aim the sensor.

=== Hot end doesn't get hot enough, so plastic doesn't extrude properly ===

Insulate the heater block well.  See [[hot-end-thermal-management|here]].

Check the power supply voltage at the Azteeg controller while the extruder is heating.

=== Molten plastic comes out of the extruder in places other than the nozzle ===

Probably, too much heat is reaching the upper part of the hot end.  Insulate the heater block well;  if it still leaks, you may have to actively cool the area that is leaking.  See [[hot-end-thermal-management|here]].

If it still leaks after correcting all that, the hot end may be damaged.

==== Thing not moving correctly ====

=== Motor moves too fast ===

If you tell it to move 1 cm in some direction, and it moves 2 cm or more instead, you may have one or more missing jumpers on the Azteeg controller.  Look under each driver board (you have four or five driver boards mounted on top of the controller).  There should be three jumpers under each driver board.

Jumpers missing under a driver board that drives an extruder motor will cause it to extrude plastic too quickly  --  perhaps //much// too quickly.

=== Motor moves the wrong direction ===

You need to flip over the motor connector where it plugs into the Azteeg controller.

(Don't confuse this condition with the following one, which might look the same at first...)

=== Motor suddenly changes direction unexpectedly ===

If a motor suddenly changes direction and goes the other way, check that both of its coils are connected.  First power down the printer, then check that the connector is plugged in correctly.  If that looks correct, pull the motor connector off the Azteeg controller and check the resistance of both coils;  also check that the connector is properly soldered onto the controller.  If one of the coils is not connected, the motor can still move, but you will lose the ability to control its direction of movement.

Once the motor rotor is moving, inertia will tend to keep it moving in the same direction as long as one coil is still getting pulses of current, but it may suddenly reverse itself and go the other way.  This can be particularly disturbing if it happens to one of the two Z axis motors;  suddenly, one side is moving up and the other down, and the X axis tilts until something fails or (preferably) a UHMW nut pops out of its holder.  (The screw protruding from the side of the UHMW nut is there mainly to keep it from rotating in its holder;  it should never be tightened so much that the nut cannot pop out during a failure condition.)  Check the second Z axis motor connector, which is soldered on the underside of the controller board;  power down the printer and use an ohmmeter to verify that each of the four pins on the bottom connector is connected to the corresponding pin on the top connector.  A cold solder joint here will cause this failure.

=== All motors refuse to move ===

Do you have power supply voltage at the Azteeg controller?

Many other things can cause this.

=== At least one motor moves, but another does not ===

Check the motor connector.

Check the endstop.

=== A motor moves okay, but it keeps moving until a hard collision at one end of the axis stops it ===

Check the endstop.

Check that there are no shorts between the endstop terminals, or anywhere else along those wires;  with the switch open and the printer powered down, use an ohmmeter to check that the resistance between the two wired terminals on the switch is infinite.

--------------

Keep these failure conditions in mind as you use the printer.  They can arise during your Flight Check, or any time thereafter.

Not mentioned above is the universal failure mode, which is a failure of the Azteeg controller or a bug in its firmware (or even a bug or incorrect setting in the host software that is directing the controller through its USB port).  This can result in a wide variety of symptoms, including all of the above and many more.


See also:  The [[troubleshooting|troubleshooting page.]]



[[jitsbuild-wires|Prev:  Wires]] < [[jitsbuild| Up to Jitsbuild]] > [[flight-check|Next: Flight Check]]

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