PRILINE Superhard Carbon Fiber Polycarbonate 3D Printer Filament 1.75mm - High Strength Glass Fiber Reinforced Filament 2.5kg Spool (Black) for Industrial Prototyping, Automotive Parts & Durable Functional Prints

After some initial frustrations dialing in this filament, I contacted the manufacturer who provided some tips and an MSDS sheet. The manufacturer was really quite responsive and helpful, clearly interested in ensuring that I had a successful experience. I've updated my review with my observations after more experimentation with this filament.Throughout this review I'm going to be comparing this material to PETG, even though it's a PC blend. This is because my primary printing experience has been with PETG, and my goal with this filament was to achieve better precision, better durability, and better temperature resistance than my PETG experiences.Hot end. I'm using a E3D V6 Hot End with Copper Heater Block, Titanium Heat Break, and 0.4mm Nozzle X. The Nozzle X is a hardened nozzle, suitable for printing abrasive filaments. It also has a nonstick coating, and I'm happy to report that this filament easily wipes off the Nozzle X at temperature.Bed surface. I'm using the Prusa PEI sheet, the regular one, not the fancy new powder coated one. My surface prep is exactly the same as I do for my PETG prints, using windex as a release agent. In general this has worked well, though I did tear out a 1mm square chunk of PEI from the sheet by getting impatient and pulling a print off before the sheet fully cooled. Make sure to let your sheet cool before removing the print.Filament diameter. I measured the filament diameter to range from 1.69mm to 1.72mm. This tolerance is fine but make sure to adjust your Slic3r settings accordingly.No Cooling Fan. I'm attaching a picture of a SirLayersalot that I printed at 60% scale with Slic3r's default "Prusament PETG" profile (while this filament is PC, not PETG, I found the settings of this profile to produce cosmetically acceptable prints). This profile included the cooling fan enabled with an auto fan setting of 30-50% and a bridge fan of 50%. Temperature was 240/85 for the first layer and 250/90 for subsequent layers. As you can see in the picture, this yielded a cosmetically nice print. However, and this is the important part, layer adhesion tests using a layer adhesion test model on Thingiverse showed that prints with the cooling fan enabled had compromised layer adhesion. With the fan enabled, I was easily able to break the layer adhesion test by hand. Prints made without a fan yielded a layer adhesion test that I could not break by hand. The manufacturer recommends printing without cooling fan. I second this recommendation -- you've paid for this expensive filament, it's worth taking the time to get a fan-less (or "fan-minimal") profile to ensure the best layer adhesion.Warping. I do not print with an enclosure, and I found warping to be minimal on the size prints that I do. I did have one very wide (from one side of the bed to the other) print pull up on a corner on me, but I've had that same problem with PETG on very wide models. Adding a brim probably would have prevented the issue.Carbon Fibers. After printing with this filament, I usually run a clear cleaning filament through my hot end. Putting that extruded cleaning filament under a microscope, carbon fibers cleaned out of the hot end are clearly visible. They are small hair-like strands.Heat deformation test. I performed a test using this filament together with PETG as a baseline reference, heating a rectangular print up at 5 degree increments, applying some load stress, until I noticed deformation. This filament began to deform at about 100C. The PETG reference began to deform at about 90C.Developing a fan-less profile. I began with the Prusament PETG profile that I used to print the SirLayersalot, and made several changes. First, I increased retraction distance to 2mm, lift-z 1mm, and retraction speed to 50mm/s. The filament does tend to ooze a bit, and the retraction will help prevent ooze artifacts on your prints. Next, I brought the temperature down to 235C. I set the extrusion multiplier to 0.98, to prevent material accumulation on the nozzle. I disabled the "fan always on" setting, and changed the fan speed to vary from 1% to 5%, instead of 30%-50%. These fan speeds I chose not to achieve any cooling, as 5% should be negligible, but rather to enable Slic3r's "slow down if layer print time is below" setting to slow down the print speed for very small layers (more on that in a moment). I set the bridging fan speed to 30%, as I think bridging is one case where some fan is acceptable and useful to achieve decent bridges. You can get the filament to bridge without a fan, but the first layer of bridge will sag a little. It's probably something to evaluate on a print-by-print basis depending on how much bridging you have. I turned on the "detect bridging perimeters" setting.I'm also attaching a picture of a "Prusa Mk3 Nozzle Fan" print that I made with this filament. It took me about a dozen attempts to dial this part in using my fan-less profile described above. The biggest issue was the small mounting tab with the countersunk bolt hole on the top of the print. This tab is a small feature, with small fast layers, and without a fan it is possible to overheat this tab and cause it to sag and deform. The solution, recommended to me on the prusa forum, was to print something else a few inches away on the bed. This technique causes the print head to move away just long enough to keep from overheating and deforming the print. So I printed two of them at a time. After the dozen attempts, I did end up with a nozzle fan good enough to install on my printer. I'm now printing the Mk3S version.The third picture I'm attaching are some large rectangular prints. These are the aforementioned prints that went from one side of the print bed to the other. These are part of a COB LED light bracket that I'm making, where I wanted a bit of additional temperature resistance beyond what I would normally get with PETG. The prints turned out at least as good as my PETG versions, are stiffer, more opaque, more matte, and should have a higher temperature resistance.The final verdict. It took some persistence getting this filament to print well, but I feel the experience was worthwhile. The resulting print is: 1) More rigid than PETG, 2) Has a higher temperature resistance than PETG, and 3) Has a nice matte finish. Plan to invest some time dialing in your settings and try to reduce fan usage to a minimum to achieve the best layer adhesion and part strength. Avoid the fan altogether if you can.