Okay, so from our last blog post (Adventures with our Prusa – Part 1) we went through a trial by fire getting things setup and if I can do anything to help others avoid such horrific sadness and burns I will. Did we learn a whole bunch in a short amount of time? Sure. Would I ever want to learn that way in the future? Nope!
So my first advice is to ignore all the stuff they say in the booklet about “squish” and “flatness” when trying to set your Z height. For noobs, I think it’s too confusing because we don’t have a good idea what “good” looks like and were super eager to just get to printing dinosaurs that we can hardly stand it. Plus there are already so many variables to go wrong up to this point, this “gut feel” solution to how squishy your filament should be is never a good one.
So we stumbled across this blog post, he argued for a simple solution: print a square. He utilized two cool features of printing. The first was a tone which would make the printer beep after a certain point during the print, for the one we selected, it would beep at the ½ way mark. This allowed you to live-ajust (aka lower or raise) the print head while the printer was printing in order to compare two different z-height settings. The second was the size of the print. These took maybe 5 minutes to print and you could even get more creative and do what we did was raise/lower the head every ¼ of the way across the square. This allowed us to test 4 different settings of the Z (head) height in as little as 5 minutes.
Our first result, clearly illustrated that our height was too high, because each line was not flat (squishy) enough to stick to the next. So we knew we needed to lower it down a bit. So down it went. Here you can see how the bottom right, was still too high, so we lowered it at the halfway mark, and it got noticeably improved!
More lower. Still. But getting closer. You can still see a bit of the bed showing through, even though the layers are adhering together nicely. Now we start decreasing the amount of Z-height we drop by. Instead of dropping say 0.2 mm down each time. We start doing 0.05 or so each. This is done to prevent dragging the nozzle across the bed (like last time…. ) and ruining things. (see we’re learnding!)
Eventually we reached a max point where the nozzle starts to begin to drag along the print and creates waves. Had we continued our larger drops. The next drop would have put the nozzle INTO the print bed, but because we are doing smaller drops of the nozzle we easily realized this in time, and could raise it back up.
As we narrowed in on our “perfect” height, we started marking increments on the squares after printing. This allowed us to easily compare each square with the previous for feel and look to see which we liked best.
Lastly we read somewhere that holding it up the light helps you easily see any issues like scraping where the filament is stretched too thin as more light shines through. Here’s that same marked filament held up to the light. If the waves weren’t identified before, it’s a lot easier to see that held up to the light.
Here 1.020 or 1.025 would be ideal to me.
Smooth to the touch. And no light shining through.
So we eventually found our Z Height = -1.025mm. What does this mean to you? Absolutely nothing. It’s our magic number. For our printer. Yours will and should be completely different. But you can still use the above process to identify your magical number. So let’s get on to making that dragon right?!?!?!
No. Walk before you can run. Young Padawan.
There’s a lot of crazy things you’re about to learn. Let’s focus on one skill at a time. That way you know if things are go horribly wonky (a technical term) it’s only because you’re done one thing wrong or instead of it being any number of twelve different things wrong and you have no idea where to even start…
Step 1) Determine Z Height. Check!
Step 2) Print something that’s already been compiled by someone smarter than you (aka translated from a 3d Model (STL) into the code the machine needs in order to know how and what to print (GCODE)).
Okay, that’s fairly easy. We selected a few of the tried and true default models that came installed already on the Prusa. Printing these successfully, tells us even more so that we have all the components of the printer configured and setup correctly. These prints are specifically designed for the Prusa and require no more work from you then a click of the “go” button.
Step 3) Find a VERY EASY model (STL) which has NO requirement for supports.
Supports are needed in prints whenever a layer is going to be printed on air. Think for example on overhangs. We want to avoid these for our next print. We want something basic and simple. I highly recommend the Prusa Slicer 2.0 for the software you use to compile STL files to GCode. It offers a Beginner/Intermediate/Advanced setting and is very well setup to help us noobs learn the basics without exposing us to the million of settings and tweaks like other programs (CURA!) might do so. Plus it’s designed FOR the Prusa making it super easy and user friendly, much like their printer!
We selected Toothless for our first print (From the movie How to Train Your Dragon). He was marked as an easy, no support needed print. And super cute. Plus it got us to our goal of printing a dragon. So wins all around.
Step 4) Print something with super a super basic support.
Have Prusa Slicer auto generate support or find a print that already has supports built in. Seriously there is no shame in not being able to figure out where and how to put supports. Prusa has a built in feature where it will automatically identify any overhang that is too steep and built up a support column to hold that area in place. Does it use more material than it needs to. Yup. Does it oftentimes put support where you don’t really need it? Yup! Do you have more successful prints because it knows more than you do (at this point)? YUP!
Step 5) Add your own supports
This time pick a model which does require supports but you manually put them in yourself. Use the layer viewer to preview each layer as it prints and identify any that might print over air. Then prevent this by adding a support column underneath it.
Step 6) Print something with Joints or hinges
Printing joints or hinges in place is seriously one of the most satisfying things to watch and even more fun to play with. Since each layer is added horizontally. It’s fun to print movable items as a single layer and even more fun to watch your friends brains explode when you tell them it’s one solid piece 😉
Step 7) Play around with print settings/filament/slicers and more!
There is no “mastering” 3D Printing. I’m fairly convinced of that. Even now, having over 150 hours on our printer, we still feel we are learning new things with each print. I plan on writing more of our adventures down as we figure things out and get more experienced. Currently we’re playing around with making a full D&D tile dungeon set (unrelated: did I mention we were nerds?) as well as more buildings from the City of Tarok kickstarter. We’re also gearing up for christmas and will have a super fun blog post (post gift giving on some awesome family gifts we’re making – but can only tease as our family reads this blog 😉 )
Hope you all have a wonderful holiday season with family and friends and we’ll see you soon with more of our crazy adventures!