PLA? No Way!

Today’s blog topic is back to 3D printing. I am still mulling over what my next Unity post topic will be.

So my 3D printer has been acting up for the last few weeks. The problem I was experiencing before has gotten worse: The plastic just stops extruding mid-print.

After some exaustive research, my problem could be any one of the following:

Print bed not level.
Print bed messy, with non-flat parts.
Extruder clogged a little bit.
Filament getting caught on the way to the extruder.
Gear pulling filament in slipping / grinding.
Temperature too high, causing plastic to burn and clog the nozzle as I print. This would be most noticeable during slower extrusion, which I believe would be the heavy fill where I was having problems.
Laptop not able to push commands to the 3D printer at the speed the 3D printer runs, causing fluctuations in behavior.
I was using ABS plastic. I heard some people prefered PLA for a few reasons, and I wondered if it would help fix things.

First thing I did was level the print bed. Mine was noticably off, especially in the part of the bed I was printing. So close it was smooshing the plastic against the bed in one location, and high enough a few inches to the right that the plastic was not touching the print bed when it extruder. The Solidoodle has three places you can use an allen wrench to manipulate the print bed height. I fiddled with these until my nozzle was the same height from the print bed at all locations, and have a flat print bed again.
Next up was my messy print bed. The center of my print bed where I had done a lot of prints has gotten pretty messy from the kapton tape scraping up. I ordered a roll of kapton tape, but it is tough to get to stick properly without little bits bumping up. I am working around this problem right now by printing in a clean part of the print bed. I should get an 8″x8″ piece of glass, I heard a lot of people use that clamped onto their print bed. It conducts heat well and is easier to clean off.
After that, I investigated my extruder to see if it was clogged. I looked up instructions on the way to completely clean it out, and removing the hot end was a complicated number of steps. My hot end seemed to have a bit of a clog, plastic was extruding very unevenly. I decided to run a lot of plastic through the hot end, hoping it would fix itself. It eventually did, the clogged bit of plastic finally came out and I had a stable extrustion from the hot end again.
The filament feed to the extruder is a tricky process. I had moved my plastic above my printer, which meant I had had to cut a hole in the roof of the cardboard house I built around the printer. I cut the hole a little bigger, and it does not seem to be getting caught on anything.
The gear that pulls in the filament on this printer is super finnicky. The swing arm pushes a bearing against the gear to keep the plastic pushed against the gear. If this swing arm is too loose, then the plastic has nothing forcing it against the gear. If the swing arm is too tight, then bearing pushes the plastic too hard against the gear, causing it to get stuck. I fiddled with this a while, removing the spring from the swing arm and reseating it, while running endless plastic out of my printer until it seemed to run stable for a long extrusion amount.
The next step was investigating the temperature. I thought I had been setting my temperature properly, but I discovered that the “custom code” step in the printer settings was overriding whatever I set the temperature to in the filament settings. I was able to adjust this, and can now set my printer to print at different temperatures.
I did not test the different temperatures too much with ABS, as I had decided at this point to try out PLA plastic. Now that I could adjust the temperature, I ran the PLA through and set the printer to a much lower temperature, 175 degrees, as PLA melts lower.
PLA did not treat me well. I will cover the problems I encountered after I finish going through my above debugging steps.
I ordered some cheap USB extension cables off Amazon a month or so ago, I heard they were extremely useful to have around, and this turned out to be true. I grabbed one and plugged my printer into my PC to try and test the performance differences. I also decided to switch to back to ABS plastic. Unforunately, when I tried to remove the PLA, the PLA snapped off right above the top of the entrance to the hot end, and my printer is now truely jammed.

So where am I now? Things are even worse, hah! My hot end is now fine and jammed up. No problem though, when I have time to work on this it’s super fun and exciting to face these challenges. My fiance does give me a lot of shit for how few prints I’ve actually done the last couple weeks, though.

So now I have a new problem: I need to remove the jammed plastic from my hot end.

My ideas for resolving this are:
Find out if there is an eyedropper that is acetone safe. At the very least for a few uses, if it degrades after a few uses then I can just toss it if it’s cheap.
Find out if it is safe to use an eyedropper to drop some acetone into the top of my hot end, and hopefully melt enough of the plastic that I can push it down with other plastic.
If I can’t do that, then I can run these steps for removing the hot end, and I know that people often leave their hot ends in acetone to clean them out: http://wiki.solidoodle.com/hot-end-replacement

My fiance insists I go with her to Metrix in Seattle to see if I can get help there this Thursday, maybe even bringing with my printer. I have put it onto my schedule, hopefully I can get some help there.

Now for my notes on PLA.

So far I don’t like PLA plastic. When melted, it is a very sticky plastic. This is probably why it sticks to build platforms very well, and has become popular for cheaper 3D printers that skip on the heated build platform. I find that because it gets so sticky, it just becomes a giant pain in the ass to work with if it messes up, such as when I tried to retract it, and it became stuck in the hot end. It also sticks a lot to the bottom of the hot end, it’s a little tricky for me to make sure it comes out without getting all gunked up. This also means that when there is a problem and it fails, the whole area just guess all gross and covered in melted plastic.

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About

Joseph Stankowicz is a software engineer who has worked in the video games industry for over eight years. The last two years have had a heavy focus on Unity development, where he helped ship over eleven titles to iOS and Android platforms. He also is really excited about 3D printing, and keeps his Solidoodle 3 printing out stuff as often as possible. You can view his LinkedIn profile here http://www.linkedin.com/pub/joseph-stankowicz/60/294/420

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Posted in 3D Printing
One comment on “PLA? No Way!
  1. Dragonhill says:

    i switched to PLA… i use 179 and 60 for hot end and bed.. i also use glass…
    i’ll never go back to abs for the solid doodle.

    I also slowed down the print speed… i’m getting near perfect prints every time..

    Oh yea.. leveling the bed is a must. i think i used a feeler gauge to get mine near perfect.

    as for drilling out,, I bought 1.8mm brass rod from hobby store..then attached to a dremmil… cut the end of the rod with a sharp wire cutter to create a cutting edge,,, the speed and heat will allow the rod to drive down into the PLA.. push and pull a little to bring it up..continue until the rod breaks through to inner heat chamber.. Do this while the hot end is around 190 or 200.. then use ABS to plunger the rest out the end,,but gennerally you have already gotten through the blockage

    ~Dragonhill

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