How to 3D print nylon and trimmer line reliably: do not dry it too much and glue your bed!

How to 3D print Nylon reliably, cleanly and hassle-free.

A well-printed and robust dual-head Nylon mount (check it here).

Nylon is flexible, slippery and incredibly tough when it is printed correctly.

For me, it is a cheap and very useful material to 3D print. It is my best choice whenever PLA is not possible, and the very reason I never use ABS (more about the materials in this post).

But the nice properties of Nylon are the ones that precisely make it difficult to print ! By the way, Nylon also produces toxic fumes when heated, just like ABS, so it better be used in well-ventilated rooms.

I tried many known and unknown techniques to print reliably, and it is time I share my experience because I am happy with what I found.  Read on for more!

Nylon sometimes warps a lot!

According to the nature of the Nylon filament you are printing, the layers may shrink significantly when they cool down. And since Nylon is very flexible (not really elastic), it drags the former layer inwards, which in turn warps the whole object up, until the part pops off the bed.
Warping is easy to see on the corners and it depends a lot on the object geometry.

See how Nylon warped a bit and pulled the useful raft on the corner?

This is mostly fixed though, by asking the slicer to add a raft, or a fat brim around the object. I found that 20 lines for a brim is usually more than enough, but it depends on the object geometry. A brim or a raft considerably increases the surface in contact with the bed which counteract the tendency of Nylon to warp upwards.

But still, a Nylon brim will not stick to a regular bed... we will address this further below.

Dry Nylon filament (as steam makes bubbles!)

Nylon does like moisture, and moisture converts to steam when heated in a 3D printer nozzle for sure. It can be heard at the end of my video of a 10-year old trimmer line being printed, or with the one below : hissing and bubbling.

Too much moisture in the Nylon filament creates a lot of bubble and a frosted-like surface that does not look like the slick one in the top image of this post. Just leaving the roll on a rainy day for a few hours is enough for it to absorb a lot of nasty ambient moisture!


There are different solutions to dry a Nylon roll, but I stopped using my kitchen oven. It may work well for an entire day at about 100°C, but I cannot stand more than half an hour as it sucks so much energy, and heated Nylon is certainly not a good idea for a cake!

Actually, just wait for a sunny day and store your spool in a transparent sealed plastic box with moisture absorbent stuff (eg. the silica gel that is found with many electronic appliances or photo gear). Place a black surface at the bottom of the box to heat it further, and expose the closed box to the sun for a day. As for me it works very well, for free, and it does not dry the spool too much.

Drying Nylon: in a box under the sun for a day with silica gel and a black layer of neoprene to heat it further. It really was enough for this big spool of trimmer line, I then keep it in a sealed bag (with the silica gel)

Still, keep some moisture to fight off delamination

Now, this is an interesting finding: it may not be so well to dry the Nylon too much. People keep telling that Nylon should be kept totally free of moisture to print well, but I do completely agree and I explain why here.

First, you get a frosted look when Nylon contains moisture, versus a slick surface. Some people may like it. But this is secondary, or even completely useless since Nylon is mostly used for strain-resistant mechanical parts.

More importantly is how sturdy is the printed part.

Just try it: print some Nylon fast, eg. at over 70mm/s and you will usually get an unusable print due to delamination, where the layers do not bond well to each other. See the box below? As far as I remember, it was printed with very well dried Taulman Nylon, at 50-60mm/s. You can see how brittle it gets, even before I removed the part from the bed!

Delaminated bottom of a box. Layers are OK but they did not stick well to the previous one. When the Nylon is very dry, it needs to be printed much slower... But I like some moisture to be left because it improves a lot bonding between the layers as the exploding steam bubbles add some texture to the layers.

Now, looking at non-dry Nylon with a magnifier while it gets printed shows how bubbles pop and tear the filament beam that gets deposited (see the video above). This results in a layer with many tiny spikes, which in turn gives an excellent ground for the next layer to bond. Otherwise, the deposited Nylon may not have enough time to melt and fuse properly with the former layer.

So here is the interesting conclusion: I can print much faster and/or with lower temperatures and still get a sturdier print when I let my filament keep some moisture! I dry my filament completely only when I want to avoid the rough surface, but I then have to print very slowly, or use thinner layers, or use higher temperatures, to let the heat fuse the deposited materiel properly with the existing previous layer.

Nylon printed parts keeps popping off my bed!

Now this is the most common and most annoying issue with Nylon. The usual tricks just fails systematically : higher bed or nozzle temperature, Kapton tape, painter tape, etc. No way.