Tips and Tricks
As the title says here are my tips and tricks:
Proto-Pasta Carbon Fiber - This is a great filament (currently my favorite) and many users have success with using a standard PLA profile. But why not make your prints better? Here are my tips and tricks based on my experience.
Reduce your printing speeds especially on the first layer. For the first layer I print at 20mm/sec, anything that will be visible is printed at 50mm/s max and infill is 80mm/sec. Use a brim, I use a 4mm brim on all prints.
Reduce the volumetric speed. The MK3s by default is set at 15mm3/s. Filled filaments in general and carbon pasta in particular don't like to move this fast. I use 7.5mm3/s.
Increase layer height. I print at 0.25mm or higher. The vertical optics of this filament are great and I don't notice any difference between 0.20mm and 0.25mm except now I don't get any clogs. The carbon fiber pieces can be up to 0.15mm thick so give your printer some margin to push that pasta out.
Use a hardened nozzle such as the E3d Nozzle X or MicroSwiss A2 hardened steel. The carbon fiber is stronger than brass and abrasive so it will wear out a standard brass nozzle in no time. If you need to get a new nozzle, consider also increasing Nozzle Diameter. I have no problems printing this with a 0.40 hardened nozzle without issue but a larger diameter nozzle (even 0.5) will decrease clogging and increase printing speed and the only negative is less resolution on the XY plane.
Increase your extrusion width on interior functions. This increases strength of the model and reduces print time.
Don't be afraid to use as many supports as you need or want. Support material is incredibly easy to remove after a print is complete due to the brittle nature of this product. I often don't need to use any tools other than my fingernails to remove everything and rarely find a need for any post processing.
As mentioned this stuff is brittle and extra care is needed when handling. Make sure your filament path is as straight as possible as this stuff does not like to bend and if there are any tangles or twists in the spool it will break. I found that taking the filament completely off the spool and let it hang loose on the spool holder minimizes tangles and improves the filament path as the extruder moves across the X axis.
Another word on how brittle this pasta is. If you are making anything that needs to be able to withstand an impact on the vertical axis use a lot of perimeters, I use 5 minimum. This stuff doesn't bend before it breaks, it just snaps clean. Also choose an infill pattern that will give the strength where you want, I use a rectilinear pattern with 50% infill, and in my tests was stronger than using 100% infill.
Finally a note on slicing, post-processing and finishing. In my humble opinion the vertical plane is amazing looking and does not require any post processing. The way this stuff reflects light is awesome. Try printing a two part model with different vertical planes, even though the two parts are exactly the same color (or shade of grey) it will look like the parts are different shades making for a very photogenic model. On the build plate I use blue painters tape, it gives a really nice texture and is the perfect amount of sticky. I have also had good results using a PEI coated sheet which gives a glassy smooth look. Without any post processing models have the texture and feel and warmth of smooth cardboard. Sanding is very easy, I started with 80 grit and progressed to 600 grit and obtained a silky matte finish similar to very expensive writing paper. To get excellent top layers you should run some tests and adjust your slicer for extrusion width and interface between infill and perimeters, and mind your top infill pattern.