Not extruding at start of print

This problem is probably the most common for every 3D printing newbie but is also very easy to solve! If your nozzle is not extruding plastic at the first layer, this can have some possible causes.

Adjust the nozzle temperature

As often it is a combination between printing speed and nozzle temperature settings to get the best results for overhangs. We cannot give you a general solution, because different materials, printers and part cooling fans influences the outcome of the overhang very much.
We recommend printing overhang tests to optimize your settings and to find out which angles of overhangs are possible.

Cold pull

 cold pull works best with slippery, soft materials – like Nylon filament.

Again, heat up your hotend to the working temperature of your Nylon or Polyamide filament, push it through the hotend as far as possible, ideally, until your previous material is cleaned out, which obviously is going to be somewhat hard if your nozzle is completely clogged. Then have the hotend cool down.
What we recommend is to set the hotend to 110, 120°C and just keep on pulling on the filament while the hotend is heating until the filament plops out in one piece. Then cut off the impure end of the filament, fully heat the hotend again and repeat the process until the pulled end of your filament comes out clean and you’ve restored good flow through the nozzle. Usually, two or three passes should be enough.

Prime extruder

Many hotends have the problem of oozing plastic when they are sitting idle at a high temperature, which creates an empty space inside the nozzle where the plastic has leaked out. This oozing occurs most of the time at the beginning of a print when you are preheating your hotend. If your hotend has lost some plastic due to oozing, the next time you try to extrude, it is likely that it will take a few seconds before plastic starts to come out of the nozzle again. If you are starting a print after your nozzle has been oozing, you may notice the same delayed extrusion.

To solve this issue, make sure that you prime your hotend right before the beginning a print so that the nozzle is full of plastic and ready to extrude.

The most common way to solve this issue is to use a skirt, which are two or more lines of filament which are usually some millimetres away from the print to guarantee a constant material flow.

Needle Method

For this method, you need an acupuncture or hypodermic needle, so that you can try to remove the blockage. Obviously, you’ll need a needle or wire that is small enough to fit into your nozzle bore, typically 0.4 mm.
We don’t recommend using a drill bit instead, because they break more easily than solid needles and worst of all, can permanently damage the nozzle if you are not careful.
Preheat the nozzle to your regular printing temperature for each material and start poking with the needle. Be careful not to burn yourself. The goal is to break the blockage so that it slips through the nozzle. The next time you push filament through the blockage will slip through the nozzle together with the filament.
You might have to go through the cycle a few times and push through a bit of filament by hand to check if you have managed to break up the blockage sufficiently. If this method does not work for you try the cold pull method.

Level buildplate

To level your printbed and to set the height of your nozzle properly, please follow the instruction of your 3D printer.

To set up the proper nozzle height or more accurately, set the correct zero position for the Z-axis helps reduce warping, getting rid of an elephant foot, but also helps to extrude the right amount at the first layer. Most 3D printers do not have a way of sensing when the nozzle touches your print surface, they just rely on an endstop or a separate sensor to probe the bed. For both cases, you usually need to manually set the zero position. The exact procedure differs from printer to printer, but the general idea is usually the same:
Make sure the nozzle is clean and ideally, heated up so that any boogers will get wiped away by the paper.

Use a thin piece of paper for stiffer beds (about 90g per m2 or 0.1mm thickness) and a thicker paper for springy beds (about 300g per m2 or 0.25mm thickness, e.g. a business card).

Adjust the endstop or sensor offset until you can feel a slight resistance from sliding the card around when the printer is at the zero position for the Z-axis. Most printers have a semi-automatic mode, by which the print head travels to several defined spots on the print surface and you must set up the nozzle height manually. If not, start in the centre of the bed for a first rough adjustment, make your way around the bed and repeat for each adjustment point. Move the print head as close as possible to the adjusters and tweak them until you get an even resistance with the calibration cards at each of them.