I use a Taz 6 Aerostruder with an upgraded heatbreak and a 0.35 nozzleX to print NylonX for high load parts including experimental pulley driven slingshots. This is something I wouldn’t do with PLA otherwise I am asking for shrapnel if/when something fails. I am very happy with the results.
V6 nozzles for the aerostruder are available in various hardened or abrasion resistant formats. Get one or sacrifice a nozzle every time you print.
As for strength… What do we mean by strength. A 1mm thick layer of NylonX is much more flexible (that pla) but also more resistant to brittle failure modes. Nylon is not a hard material, but it has a much wider range of elastic deformation. The carbon fibers are a totally different beast than laminated carbon fiber, and can be used in a variety of ways in my experience, but none are really analogs to impregnated carbon fiber.
Ways I use NylonX that seems to yield better/tougher parts.
Force Distribution. If I run my line width wider than my nozzle, the additional “smoosh” causes the fibers to redistribute at angles to the direction of travel in the nozzle. With proper layer bonding, this causes there to be more “force lines” tangent to the layer/nozzle direction. This seems to reduce the deflection under load while not compromising the ductile nature of the Nylon. This doesn’t increase the bearing capacity directly as that is mostly a product of geometry/thickness.
“Stable but Flexible” parts. If I run my line at the nozzle size, and it’s significantly smaller than the filament bore, we start to see more aligned fibers. This allows for “weaving” of the directions of force and produces an overall shape/size stable object that is also flexible. This requires “speed” as well as too slow of printing can lead to more “smoosh”
Chopped the second image here of drone plates cause I’m new so can’t post multiple pictures.
TLDR v6 Hardened or Other Nozzle ( I use NozzleX), and don’t expect it to be super skookum unless you really pay attention to your printing directions and layer adhesion