Order of solving printing issues

Question

3D Printers (those who print, not the machine, dummy)!

I haven't been printing in a while, so when I returned to my Monoprice Select Mini VII, of course it had been sprung out of whack. Some of my first prints would not even come out of the extruder until I realized I had some pretty bad (and worse, unnoticed!) heat creep going on. After fixing that issue, it became apparent that many more persisted.

My question for you all is this: In general, what problems should be addressed first when looking at a complete disaster of a print?

I'm not going to specify any singular problem, but I am interested in seeing the "order of operations" for general problem solving when multiple issues exist. For example, "Fix bed height before anything else; this is a common problem that produces multiple others." Hopefully, this can help others with multiple printing issues, too.

Answer 1

for sure the answer could be dissertation or even a book because there is no simple way to address "all" issues - it's just to wide area

but as the simple troubleshooting i would list it this way

1. is your printer alive so is it
   • working at all (check power, cables)
   • communicate with the world (check app, drivers, cables)
   • moving HE and heating HB (check jams, end-points, belts, screws)
   • is it extruding (check heating, temperature, HE jams, filament path)

if all above is "yes" then

2. is your printer making printouts and are those printouts
   • starts and continues (check heating HB, HB adhesion, leveling, cooling)
   • finished at all (check all above again, stepsticks temerature)
   • keeping the shape (check screws and nuts, couplings, stiffness, stability, temperatures)

if all above is "yes" then in general you are half way ;)

3. common issues - printout is
   • bent or skewed (check geometry, stiffnes, leveling, belts, vibrations, stepsticks temerature)
   • wrapped or overextruded (check temperature, extruding, printout angles)
   • underextruded (check filament flow, filament path, stepsticks temerature)
   • stringy (check temperatures, app settings)

that is the main path i think. all above is more or less applicable to all DIY printers and all prusa clones and all clones of clones ;)

it can go wrong and fork in all possible moments as there is so many aspects to screw...

Answer 2

The obvious ones first

This is, well, obvious. It is, what a visual and smell inspection shows. Stuff like missing or ruptured cables, bent rails, ripped or very loose belts, burnt smell or hung up software that is easy to see that it is going on needs to be addressed first.

The not so obvious next

Next on the list are problems that have no obvious cause and effect. My order of operations to find these is like this:

• Homing
• movement of XYZ
• Bed leveling
• Heating test to 200 °C
• Extrusion of some millimeters
• Retract some millimeters

That solves the basic mechanical side, it shows that the machine technically could print. It is a visual as well as audial inspection. It also prepares the printer for printing.

A test print next

What's next, after having a machine that theoretically should be able to print is to print.

Start with a simple thing. A cube for example. It shows problems with bed adhesion, surface finish, extrusion, temperature, layer shifting and layer adhesion.

Half of these problems are usually the result of temperature control. The rest but for layer shifting usually as a result of slicer settings.

• Layer shifting, the odd one out, most often would either be caused by a mechanical problem are using speeds which the printer can't cope with.
• Surface imperfections like blobbing shows too much extrusion and heat.
• Ghosting so that the printer is resonating with its movement.

Answer 3

Assuming there's something on the print bed, I usually look at at what the result is to determine what to check on the printer next.

Before doing anything physical with the printer, check your settings. You should have a decent understanding of what changes what and how the different numbers affect the print, as well as what they "should" be. Review them and make sure there's nothing that looks out of whack.

Now for the specifics:

If it looks like the filament didn't extrude right, for example if it stopped extruding halfway, barely extruded at all, or there's gaps in the print, I would check the hotend. Reload the filament and push it through by hand to make sure it's not jammed. If the nozzle is fine and it still looks like you're having extrusion issues, I would check the following things:

• Wiring to the motor
• Excess tension on the filament before it goes into the extruder (bowden/guide tubes, etc.)
• The nozzle itself. Nozzles do wear out and they're relatively inexpensive so if I can't solve an extrusion issue with reloading the filament, the next thing I do is replace the nozzle.

For mechanical issues, it's a little more complicated. The very first thing I do is pluck the belts on my printers and make sure they're tight. It should play a low note somewhere around a G. If it's a thud, the belt is too loose. If it's a really high sound, the belt is probably too tight. Another thing I check is to make sure all linearly moving parts (such as the print bed, carriages for the nozzle, etc.) only move in the direction they are supposed to. Wiggle them back and forth and make sure nothing is loose on the printer.

If you don't find anything that would obviously indicate what the problem is, run the print again and watch it closely. If it's only messing up in a certain part of a print, make sure you watch what the printer is doing when it gets to those areas. Make note of the nozzle distance to the bed at startup, retraction and hopping during prints, and making sure no wires or anything are getting snagged. Listen to the printer too, if it's making any new noises such as clicking or grinding then you most likely have a problem on your hands.