makeSEA Knowledge - Printing Magnetic PLA from Proto Pasta with Replicator 2X
Printing Magnetic PLA from Proto Pasta with Replicator 2X
There are nice new 3D-printable materials. How cool would it be to design objects which contain materials with different properties, different than just colors. So I ordered a Replicator 2+ and some spools of filament from Proto Pasta. When it was finally delivered, I couldn't wait to try the magnetic PLA (actually it should say “ferromagnetic” because the material is not a permanent magnet, but it can be attracted by a magnetic field).
This is the result, when I was using the Makerbot Slicer with default PLA values (230°C) and the magnetic PLA from Proto Pasta:
The printing worked well on the first layers, but all of a sudden it stopped. The feeder motor was skipping steps.
The test-object has a shape of a short cylindrical tube with some sort of flange and screw-holes. Diameter is 40 mm and height is 15 mm.
With blue ABS the printing had succeeded:
I played with different temperatures from 190° to 230°, but it still stopped after a few layers with the feeder sometimes grinding, sometimes skipping steps.
Earlier, I also tried with regular PLA, which worked at 230°C, but not fully satisfactory. The result was a very wavy surface—the temperature was by far too high, but lower temperatures also resulted in a clogged nozzle (it’s a bit difficult on the picture to recognize the mediocre printing quality with the black color).
I asked Makerbot support for help, but their response was that the Replicator 2x is only designed to print ABS and nothing else. Searching Google and YouTube wasn’t much more helpful, because there were too many unspecific results: people were printing with ABS on the R2+ and PLA on the fifth generation Replicator. Others were printing both materials with highly modded wooden pioneer Replicators, and it was not clear what makes the difference.
So, I started my own investigations. I started printing again with the magnetic PLA, and waited until it clogged in the nozzle. Even though the nozzle was still hot, it was very difficult to pull the filament back by hand (luckily the new print head allows you to easily release the feeder pulley). The filament looked normal. It only had a small bulge between the cold and the hot part:
I then disassembled the whole print head, fixed it in a small vice, and heated up the nozzle (using “pre-heat” from the printer menu). Without feeder motors, I pushed the filament manually into the nozzle, but it never got stuck. Everything worked: normal PLA, magnetic PLA, conductive PLA, ABS, and even PETG. It wasn’t possible to reproduce the clogging. I was using the vice, because I didn’t want to burn my hands when holding the main mounting block with my fingers, but I touched it anyway—it was surprisingly cold, somewhere around body temperature. Strange…when printing, this block gets much hotter…
Thus, I next installed a hair dryer and heated it until the main block was feeling really hot. While still pushing the filament through the nozzle by hand, I found it needed more and more force with the increasing temperature. It seems that the friction inside the thermocoupler is increasing. So I was wondering, where does the heat come from during printing? My guess is the feeder stepper motors. The are both always turned on while printing.
When reassembling the printer, I added a sheet of paper as a thermal isolator between the motors and the main mounting block. I also placed a strong fan on top of the printer in order to sufficiently cool the motors (and the thermocoupler).
This setup had a positive effect, but still needed improvements: it was now possible to print many more layers until it clogged. Still no success, but at least I learned where the problem is located, and I was able to Google for the right terms.
I finally found several providers of different types of nozzle and thermocoupler—some with special coated surfaces. I contacted http://www.micro-swiss.com/ and got really honest and feasable explanations. The problem is named “cold end clog." A different nozzle itself is not sufficient to resolve the problem—also the thermal barrier tube needs to be much more efficient and with less friction. Unfortunately, there are no compatible replacement parts for the R2+.
In various forums people were also discussing lubrification of the filament. For me this seemed the last solution, because I didn’t want to contaminate the nozzles with some vaporizing oil. It’s unclear where the oil finally goes. Encouraged by Chris Stavros I gave it a try: I designed a filament cleaner, which holds a sponge soaked with silica oil. My cleaner box can be removed and added to a filament without unloading the filament from the extruder.
In addition to lubrication, I removed the side covers of the printer and positioned the fan in order to create stronger ventilation on both extruders, the feeder motors, and the printed object.
The effect of lubrication was amazing. Magnetic PLA prints without clogging at 220°C:
The nozzle, however, is oozing quite a lot, but at least it was possible to do a first successful print with magnetic PLA on the R2+. Finally, I reduced the temperature to 210°C and was using Simpify3D (the software does much less travel moves over empty areas). I’m very satisfied with the final result.
Magnetic PLA used in this test purchased from: