YouTube – 3 Tips for the Prusa i3 MK2

I decided to try something completely new recently: I created a YouTube channel! So far, I have a few videos showing my new foray into the maker movement. My latest video, which was just released, gives tips for anyone new to 3D printing or with a new Prusa i3 MK2.

I recently received my new Prusa 3D printer, which is the first 3D printer I have ever owned! With my history with 3D modeling, animation, and electronics, I thought this was a great next step. And it has been a lot of fun!

But the first few days with my new 3D printer were a bit troublesome, because I ran into some basic problems that were caused by a lack of knowledge. So I wanted to share some of what I learned, in the hopes that it saves other people time and frustration with their 3D printers.

Tip 1 – Get calipers

Calipers are an essential tool for 3D printing. Using your calipers, you can measure and verify the size of your prints. And anytime you design a new piece that needs to fit into an existing space, your calipers give you precise measurements for your design. 3D printers work with tolerances measured in fractions of a millimeter (the Prusa can print at .05mm precision), so you often need the precision that a good set of calipers can give.

Fortunately, you don’t normally need a very expensive set. You can get away with an inexpensive set from Amazon, which currently costs $11 at full price. I bought a slightly nicer set and it only cost about $25.

If you don’t already have a set of calipers, buy them immediately. Just consider it part of the cost of owning  your 3D printer.

Tip 2 – Set your first layer height correctly

Failed 3DBenchy Print
The first layer height was set too high, so the model detached from the build plate during printing (click for full size).

The first layer will make or break the final print. If the first layer does not print at the right height, the print will either have a little squash at the bottom of the model (known as “elephant’s foot”) or it might not stick to the build plate (which is disastrous – see the image to the right).

Calibrating the first height varies by model, but with the Prusa you can use the “Live Adjust Z” setting. Unfortunately, I found the instructions to be a little vague, especially for someone that is brand new to 3D printing, so I wasted a lot of time trying to get it right and I still ended up with a setting that was too high.

I wasn’t even really sure what was the goal of the calibration! After doing some research online, I found that the final “Live Adjust Z” height should be slightly lower than the height of the first layer. Since the default settings in the Prusa Slic3r set the first layer to .20mm, the nozzle should be at about .18mm when it prints.

Fortunately, I also found a fairly easy way to get the nozzle close to that value:

  1. Find a piece of paper or card stock that is about .2 millimeters thick (use your calipers to measure!). I found that the two pieces of paper that shipped with my printer together measured .19 mm, so I used those.
  2. Set the “Live Adjust Z” to 0.00. This is important: the next step ignores the current “Live Adjust Z” setting, so you will end up with a bad setting if you skip this step.
  3. Tell the Prusa to go to the Home position (Calibration->Auto Home).
  4. With the paper under the extruder, play with the “Live Adjust Z” setting until the nozzle is slightly catching on the paper. Now you know that the nozzle is about .2mm from the print bed!

You will still need to tweak the settings to get it perfect, but at least now you know you’re close. Just run the Z-Calibration G-code a few times until your print looks good.

Tip 3 – Calibrate your extruder motor

During my research for the first layer height, I found out how to check and calibrate the printer’s extruder motor. The extruder motor pulls in filament and pushes it into the hot end. If the motor is pulling in too much or too little filament, your final print will suffer.

Fortunately, identifying and fixing this problem is easy. I quickly tested my printer with the silver filament from Prusa and found that it was under-extruding by about 6%.

Here is how I tested my printer to get this value:

  1. Using a marker, measure and mark your filament 150mm above where it goes into the extruder assembly.
  2. Make sure that the extruder is away from the print bed and pre-heated, then tell it to extrude 100mm of filament (in the Settings->Move Axis->Extruder menu).
  3. After the printer is finished extruding, measure from the extruder assembly to the mark you made in step 1. Subtract that measurement from 150 to find out how much filament was actually extruded.
Slic3r Extrusion Multiplier
Example Slic3r settings for the Extrusion Multiplier (click for full size image).

If the value wasn’t 100mm (or very close), then your printer needs calibration. Fortunately, this is easy through Slic3r:

  1. Calculate the multiplier you will use by dividing 100 by the amount of filament that was actually extruded. For example, my silver filament only used 96mm, so the multiplier is 100/96 = 1.04.
  2. In Slic3r, go to the Filament Settings section.
  3. Enter the muliplier from step 1 into the “Extrusion multiplier” value.
  4. Reslice your model and use the new G-code to print your model.

I recommend testing any new filament you buy. Once you figure out a multiplier for the filament, you should save it as a filament preset so you can easily switch between filaments.


When I fixed the first layer height and extrusion calibration, my print quality dramatically improved. Check out this comparison:

The left print was before I fixed my layer height and extrusion calibration. The right print has a much better, filled-in first layer.
The left print was before I fixed my layer height and extrusion calibration. The right print has a much better, filled-in first layer.

The 3DBenchy on the left was my original print, before I fixed anything. You can see that the bottom layer isn’t fully filled in. And the center of the “D” text actually fell off after printing!

After fixing my settings, the 3DBenchy on the right has a solid bottom layer with no gaps and barely any print lines.

Thanks for following along and I hope this helps you get started with 3D printing! If you have any other tips for people that are new to 3D printing, please put them in the comments below; I appreciate any help in improving my prints.

And let me know what you think of the YouTube video!

  • Awesome – looks solid! Can’t wait to hear the details involved in creating the videos.

  • BobTheBuilder

    To get the red benchy, did you have to lower your Z adjust (make it more negative)? I used the silver PLA that comes with the MK2, and while my bottom layer is smooth to the touch and looks filled in, there are still very prominent layer lines. Lowering the Z axis (benchy on the left) didn’t seem to make much of a difference in terms of layer lines, but it did cause the edge near the z to be a little ragged. Thanks!

    • No, once I set the original Z-adjust, I haven’t changed it for any of of the PLA filaments I’ve used (3 so far). It’s tough to tell for sure in the photo, but the side near the “C” looks a little smoother than than the side near the “z” — maybe you need to use the advanced bed level correction settings to tweak one or two sides, so the bed is perfectly level. I ended up using that feature to get the best bed adjustment. It took some trial and error, but it was worth the up-front time investment. Even a small adjustment to one quadrant of the bed can make a noticeable improvement to that first layer. Good luck!

      • BobTheBuilder

        Oh, interesting, will look into that. Thanks! So the main difference between your silver benchy and your red benchy was extrusion motor calibration?

        • Oh, sorry, it’s been a while. Yes, the silver benchy in my picture did have the Z-adjust a little higher. The print lines are too pronounced in that print and not squished enough — you can clearly see it in the outline of the letters.

          Your print looks pretty close to being good, if you can get both sides of the print to look the same.

  • Jack

    in the instructions on how to run the XYZ calibration it says to place a piece of paper on the print bed when the calibration is running. then it says to turn off the printer immediately if the nozzle snags on the print bed because failing to do so can harm the printer.

    Why is using paper to calibrate The nozzle height different from using the paper in XYZ calibration?

    • When you’re using paper to calibrate the nozzle height, you are controlling the nozzle movement — so you won’t dig the metal nozzle into the print bed and do any damage (presumably). But when the XYZ calibration is running, if the bed isn’t level and the nozzle height is too low, that calibration could cause the metal nozzle to hit the print bed and then keep going, scoring some damage into the print bed. So the paper is there to let you know if the nozzle gets too close, so you can turn off the printer before anything bad happens.

  • Paul Gan Sher King

    for your calibration extruder under part 1. your wrote “Calculate the multiplier you will use by dividing 100 by the amount of
    filament that was actually extruded. For example, my silver filament
    only used 94mm, so the multiplier is 100/96 = 1.06” was the the 96 just a typo? it should be 100/94 = 1.04 right?

    • Hi, Paul, thanks for pointing out that typo! I actually measured the filament at 96mm, so the multiplier is 100/96 = 1.04. I fixed it in the article! (Sorry for such a late response — I was on vacation and away from my computer).

  • Tonio Bugeja

    I am a cnc machinist with 25 years of experiencing in running VMC`s 5 axis turning centers, eroders… this should have been a piece of cake but I found it tough following the instructions was not any help… I have found a way to set the nozzle and the sensor which is what really counts. I set them 1.15mm with a feelerguage with the live adjust turned at zero.
    I have another problem…
    The extruder is jamming….The nozzzle is hot (i just touch it with a piece of filament and it melts) but the filament can neither be fed down by hand (it should be easy to do so when hot) and neither comes out. I dismantled it several times. (The parts are very very fragile and are not made to withstand dismantling and re-assembly over and over and I was thinking of producing an extruder housing from aluminum. on one of my cnc machines.)
    I am suspecting that some molten material is being pushed up and there is a gap somewhere and the melt is forming a grip. I found that with patience and heating the extruder for quite some time I can push the filament and work, but I have ruined many prints…
    maybe somebody found a fix for this…
    One other thing maybe somebody thinks about it is an external control- hard wired – of the facility to pause the print which I need to go active when I have a need to stop the print without having to restart from scratch.

    I intend to manufacture a printer with double the sizes but will make some serious design…