Normally when processing g-codes, the printer continues to execute the g-codes as they are received (well… as fast as it can physically process them). However… there are a couple of codes that tell the printer to “wait” and not proceed until some condition is true.
For example…
M104 says to “set” the nozzle temperature… but this code sets the temperature without waiting.
M109, on the other hand, says to “wait” for the temperature … the printer will not continue until the temperature is within acceptable range of the target temperature. This can cause a printer to just stop.
Similarly, M140 and M190 do the same thing except they set or wait for the bed temperature.
Once you connect with Cura, go to the “Monitor” panel, make sure you are connect (you can click the “connect” button) and then open the “Console” window.
In the console window try a couple of g-codes (manually type them). AFTER typing each of these test g-codes, press ‘enter’ to send them to the printer (it wont do anything until you press enter).
For example, try to ‘home’ the printer in all axes by typing:
G28
Does it ‘home’ the printer on X, Y, and Z axes?
If yes, try a basic move command… enter:
G0 X100 Y100 Z100 F1500
This will move the print-head to the X=100mm Y=100mm Z=100mm at a speed of 1500mm/minute (25mm/sec). BTW, the printer also has an “E” axis. That’s the extruder motor. It advances or retracts filament. But we wont insert an E move on this line because your hot-end isn’t heated and we don’t want to try to force cold filament through the nozzle or it’ll just end up grinding filament.
Does the printhead move on all three axes?
Try setting some temperatures.
Set the bed temperature to 40°C (I’ll use a low-ish temperature here just so you don’t have to wait a long time for the bed to heat up) type:
M140 S40
Watch the LCD display to see it shows the bed has a target temperature of 40°C and also watch the actual temperature to see if it is actually heating the bed (is the temperature climbing toward 40°C?)
If the bed heater is working as expected, go ahead and turn it off (just set the temperature back to 0) using:
M140 S0
Test the hot-end. Let’s set it to 180°C by typing:
M104 S180
Again… watch the LCD panel on the printer to confirm that the nozzle’s target temperature has been set to 180 and that it actually is heating to that temperature. 180°C isn’t particularly hot for a nozzle so it shouldn’t take too long to reach that temperature. Sometimes a thermistor can go bad and doesn’t accurately report the temperature while the hot-end is actually heating. If the hot-end is heating but the thermistor doesn’t think it has heated enough, it can result in a thermal runaway condition (you may see an error message on the LCD and/or alarm.)
Monitor as the extruder heats … because if you do have a bad thermistor you might see the temperature jump around rather than heating up as expected. Defective thermistors can report erratic readings … instead of the temperature climbing a few degrees at a time… it might fail to climb … then suddenly report a huge jump in temperature… then a few moments later report a cooler temperature, etc. You should get a fairly consistent heating trend without the temperature jumping around.
If you DO see it jump around, you likely have a defective thermistor. Switch off the printer (it isn’t going to work correctly and frankly isn’t safe to operate … defective thermistors can over-heat to the point of causing a fire. Your printer does have thermal run-away detection (the board realizes it has been supply far too much power for too long for the hot-end not to have reached the desired temperature over some period of time and suspects the thermistor is broken … and will typically display an error message and/or sound an alarm).
If the nozzle is working as expected, go ahead and turn it off (set it to 0°C) by typing: M104 S0
You can look up g-codes here:
If there is an issue with the printer itself, then my guess is that one or more of those commands wont work as expected.
However, if everything works as expected, there may be something wrong with the start g-code. You mentioned it doesn’t even do a nozzle wipe… and the only the reason that would happen is either (a) it hasn’t reached the desired temperature or (b) you’ve inadvertently editing your ‘start’ g-code and there’s something invalid in it. But if that’s the case, you can just restore the correct start g-code and you should be good again.