This story extends from my last blog post (click, HERE, to view)....
It wasn't long before the simple models printed on my new Printerbot "Simple" did not meet my expectations. View the pictures below:
First off, the picture on the left represents a series of prints cancelled mid way through the process. What you'll notice is that the texture of, what should be a gem of a 3mm cube is all smashed together. This is the result of the Z probe (the up and down movement) not being calibrated properly. When things are working out okay, then the square on the right occurs, and you'll notice too that the texture of the square cannot really be defined as "smooth." These mediocre prints resulted in an endless series of printer bed calibrations. All to make sure the printing surface was perfectly flat and also adjusting the G-code in the Cura software so the nozzle drifts higher or lower as it drops plastic out. In the end, the perfect specimen was never achieved during the early stages of my life with the Printerbot.
One day I was sickened by the dastardly prints being produced which looked like nuggets of plastic junk. Our school "Technology Integrator" came into my room and I told him exactly what the problem was; to reiterate what the problem was it's that the 3D printer was not printing out decent 3D objects. Thus, I offered my desk up as an opportunity for him to work with the device until I returned from teaching a class. And when I did return it was to my horror that this had occurred:
To this day I don't know how the printer nozzle hovering above the bed occurred as things were never this bad before I left to my class. But if the video does not state the obvious, you'll notice that the Printerbot is printing way up above the printer bed and that can't be right. This put me into a panic because how was I supposed to produce six Pokemon models for my 6th grade advisory group. Models which had failed to print only days before as a result of becoming unglued from the printer bed (I'll get back to this in a bit).......I had promised people all sorts of trinkets....dolphins, Notre Dame figurines, monkeys, elephants and pen holders....oh the feeling of destiny delayed.
Having the Printerbot not return to printing anywhere close to the surface put me into a lonely state of mind. When I'd return to work each morning and see the piece of junk sitting on my desk I'd feel like I lost my pet cat Felix to an automobile. Felix was my favorite cat and even today, I miss him terribly.
And every single time I'd press the print model button in Cura the nozzle of the machine would move out to a location on the bed, raise up a little bit, stop for a while, then continue raising up to the ridiculously high point while dripping plastic.
I tried everything to fix the Printerbot. I even flashed the micro-controller board at the bottom of the machine per the instructions listed on the Printerbot page. Nonetheless, my valuable prize was quickly turning into a piece of metal non-sense. Poets would probably have a field day painting a picture of how useless the thing was in words....
Even as I went through every online forum I could, every Google search I could bring myself to produce, nothing changed. In the depths of my desperation, hitting rock bottom, I loaned the printer out to our school's IT technician. Anything to fix the machine at this point and he decided to take it home for the weekend this was the result:
Yes, the micro controller board is smoking! Producing the types of fumes that make you feel like your fertility is dropping with each puff. This was definitely not the kind of smoke you'd find in a Jimmy Buffet concert. Nonetheless, this was an absolute disaster for me and I was distraught. My lovely printer was failing miserably. It was at this point that I felt I had reason to request some type of product exchange so I first contact element14.com who then referred me to the Printerbot to deal with repairs. The picture below shows the point at which the damage on the board had occurred:
The video of the microcontroller board smoking was actually made for "Mike" who works at Printerbot. Mike must have woken up each morning with another of my requests to fix the thing. He probably thought I was composed of printerbot "noobness," over his Starbucks coffee- that was until I sent this video of the printer smoking. I just wanted my gem of a prize to work again, to feel the warm glow of elation each time a new Pokemon figurine was produced rather than the buzzing of the printer dropping more loads than a flock of sea gulls.
To the Printerbot people's credit they eventually sent me a new microcontroller board (upgraded to a higher revision) and also a new Z probe sensor:
I forgot to mention that the expedited shipment of the Z probe happened after a couple weeks because they were out of stock of the microcrontroller boards. Which made me ponder...were the issues I was having something others were experiencing as well? Maybe my suffering is shared; like a Jungian sort of thing?
Anyway, turns out that the board and sensor really was the issue because now my Printerbot was actually printing on the surface bed. There were two other issues though, the first was terrifying again, in that when the Z probe would lower to the printing bed there would be a loud crashing thump. Sounded like something crashing, and it turns out that this was the result of this screw being loose in the mechanism which raises and lowers the printing nozzle:
There are still times when I have to tighten up this screw which I think comes loose from having to manually re-calibrate the Z probe from time to time; this process of re-calibration involves screwing the Z probe shaft down again after raising it up 30 mm and this probably has some type of undesirable effect on the screws. Another "screw" problem which I experienced was the spool feeder not feeding the plastic filament into the extruder. Observe the following video to see what I mean:
The red mark I made on the filament with a pen is not moving so obviously plastic is not being fed through the small cog leading into the extruder. Turns out that you have to turn the screw located at the top of the cog so the filament gets locked (or rather pinched) into place and the "bite" marks on the feeder actually grip the plastic to put it in motion.
All these issues aside and once fixed, the most frustrating difficulty I had involved the things I was printing not sticking to the surface. Notice the following cancellations to prints I had to make as a result of the issue:
What an absolute waste of plastic!
I can't describe how frustrating it is to have your model print for a couple hours and then have to cancel it as a result of the bits slipping off of the surface. Half those Pokemons look like they were guillotined by Louis XVI; Pokemons probably have no necks thus why they are severed at the trunk?...In the end, we tried to use hair spray over the blue tape (as this was what was recommended online) and this worked somewhat better. Also, I adjusted the temperature at which the PLA plastic was extruded through the nozzle; but nothing worked all that well. So, my solution was to line the board with double sided duck tape to absolutely guarantee that my models would not shift during the print:
You can see that with models with a narrow small base which would otherwise have issues now stick. However, double sided tape is not ideal because:
1. It is expensive
2. Sometimes it's hard to remove from the printing bed.
Additionally: NEVER use double sided carpet tape. I found this out the hard way.....that stuff does not come off of a metal surface easily....
These days, I've figured out that you need to experiment with the brand of blue printers tape that you use. I've found one from Lowes that I like and in combination with hair spray being layered on the surface just before the print, so it hardens and becomes sticky as the first layers appear, you can finally achieve a satisfactory print. There are times though, when I want to guarantee that my model will not be messed up so I use the double sided duck tape and this also involves the additional hassle of having to re-calibrate the Z probe slightly higher to account for the tape's thickness. The prints that I make now also involve me selecting an option in Cura which is to lay down a "brim" around the model. What this is is a series of lines (think of it as a skirt) to your model which widens the base further and provides added adhesion between the structure and the bed. The drawback in having to do this is two fold:
1. Your print will take longer to produce and
2. You will use up more of your PLA plastic in the process of laying down a brim around your model
So there you have it! A plethora of problems which those with the Printerbot Metal Simple will hopefully never have to experience. Once all these issues were worked out I managed to achieve a series of wonderful prints which kick started my ideas for how to use the 3D printer as a tool for the classroom. My next blog post will explore the form factor of those prints and also how the settings within Cura have to be experimented with and manipulated depending upon the characteristics of the model you try to produce.