Printing with nylon is hard, messy, stringy, warpy, and extremely rewarding.

Nylon is slick, in any aspect you look at it.

In fact is so slick your extruder will skate on it instead of pushing it in the nozzle.

I am printing with difficult to print filaments for years now, if you think ABS is hard to print with... think again.

So how do I print with nylon, ABS, PPS, or PEKK, PEI, PEEk?

I do what I have to do to make my machines compatible.

Warping, it occurs due to uneven cooling of the printed object, since most polymers (or metals for what is worth) grow in size (swell) with temperature rising (water shrinks, but that is an exception) towards transition from solid to liquid, the opposite is also true, they shrink with temperature lowering accordingly.

Here you have a printed object maintained in temperature at the base by the hot platter, molten on top by the nozzle and cooled in between by any air draft happening around, hence it shrinks in the colder parts accordingly remaining hot at the base, dimensions within the said objects change and the shrinking part will try to coerce the non shrinking part to follow, resulting in bending it up from the platter, peeling it off.

The rest is a mess.

In order to prevent this you need the whole environment hot enough to prevent shrinking anywhere in the object before is printed 100%, rule of thumb, around 30% to 50% of the melting point, most materials are happy with 30%.

Hence full enclosure of the machine is required, sometimes an extra hand with heating it up too (a bathroom fan does the job up to nylon, above that you need hotter air, so maybe an industrial little fan used to peel off paint might be a cheap and good enough solution)

The simple way to enclose it is to throw a large cardboard box upside down over the printer after the first layer is done, but if said box is transparent is better for you since you can inspect visually without raising said box and inducing air drafts in mid printing.

So if the box is transparent good, if it has doors; one on the filament path side just in case you need to mess with it, and another one where you have access to the platter is even better.

Also fighting warping mechanically proved invaluable for me. Fro this I use large brims, 20 mm around, plenty of glue stick, and once the brim is layed and a few layers are printed, I put some 2 mm thick 30mm wide Aluminium plates as long as the whole bed on the brim left and right touching the printed part base for as much as possible, and clamp them down with paper clips, large ones made of spring metal sheet. Cheap and efficient, should warping peel off my brim after a few layers, I have the metals to hold everything down.



Extruding:

Your regular Bowden extruder here is not going to be of much help. First you need to place a stronger stepper motor, so buy one and slap it on the machine (keep the extruder mechanism, most of them are OK) Same Nema 17 but with more amps drawing, and tune accordingly the stepper driver.

Now that you have double the horse power, you need to press more against the filament, so you need to replace your extruder tensioning spring with one that can push some double to triple, or the gears will slip against the filament all the time resulting in under-extrusion. If you are quite there but not yet, a method to make the spring pushing more is to cut some washers a channel so you can sneak them under the spring, I piled up 4 washers to help the stronger spring make it.

Is called fine tuning... lol.

Your direct drive extruder cannot be beefed up like this, so you ad an extra Bowden extruder to help with pushing, buy a Y split stepper driver cable adapter, and take the motor cable commands to both motors, make sure the Bowden motor is as above, make sure the number of steps per rotations is the same as your direct drive extruder and that it rotates accordingly at the same imput.

Do NOT forget to fine tune the stepper motor driver on the motherboard to cope with the extra amps load.





Dry your filament thoroughly.

Nylon and most high temperature filaments are like vacuum cleaners when it comes to moist in the air (and to moist in the water too).

If there is any, be sure the Nylon magnet will drag it in it's molecules from a mile away.

And will not easily let go of it.

PLA, ABS, HTPS, PETG, you can dry at 40C minimum 50C maximum in a cheap food dryer, ventilated, in 24 hours or 48 hours tops. Even a few 1Kg spools in the same time.

Nylon, PEEK, PEKK, PEI, PPS and similar... I sometimes keep them a whole week or two, at 80C, and it still pops in printing a bit. Those filaments even if completely dried when you throw them in the printer, will suck humidity while printing, and in mid print you find your hot end puffing like a bong of dope.

So keep them in the drier while printing, make a Bowden Teflon tube connection to the printer, put a filament spool aider (holder) in the drier, drill a hole in the side wall and bring the Teflon tube in, this is how you minimise your moisture intake while printing.

Remember: Filament in the food drier, passing straight to the extruder through a Teflon tube helps, a lot.

My drier temp for Nylon and above is 80C day in and day out, even when not printing, my printing chamber is 80C or 100C when printing, depends on the filament requirements, my platter is 80C or 100C, or 120C, depending on filament. Yes I know; in the winter sounds great, no other heating method is needed in that room, is at 30C all time, I can stay in my trunks there no problem. In the summer thou... windows wide open or I boil in my own juice.



And that induces one other problem, your heat sink takes hot air from the heated chamber to cool the filament path. And it does not cool it anymore, so your filament jamms all the time. This is why I swapped all my heatsinks to water cooled blocks, and besides the printers I have a water jar, pump, radiator circuit to cool down the water coming from the heat sink before sending it back in to refresh my filament path.