Nylon Problem

[darkglove 3]

Hi,

Still a noob.

I recently got a sample of Nylon to try out. I've been printing with PLA no problems but the Mrs hates the smell. I found a few settings that people have used for Nylon and none of them seem to give me a good result.

Everyone seems to recommend turning the fan off but I've found that if the fan is off then my print ends up being a bubbling molten mess.

If I turn the fan on then it starts to print perfectly until it gets to about 8mm high (I'm just printing a test vertical cylinder) and then it seems to just stop extruding.

So if the print is fine for, approx 10 mins, what could cause the element to stop?

Is it under-extruding a small amount and it's gradually getting to the point where it runs out?

Or under-extruding so the heat gradually works it's way upwards creating too much gunk in the head?

My rubberduck debugging seems to be leading me to under-extrusion.....

[ignatius 22]

Hi!

The reason why you get under-extrusion with the fans on, could be because Nylon gets cold faster than PLA. If you have the fans on, it could clogg inside the nozzle because the Nylon gets to cold to go through, that's why is better to print with fans off.

The bubbling you have is because of moisture. Moisture is a very critical issue printing with nylon because every bubble is a spot you get on your printing, making the printed object much weeker and fragile.

If you keep the filament dry, you could get nice prints with nylon, incredible strong and still flexible, depending of the infill %.

Which kind of Nylon do you use?

Edited November 8, 2015 by Guest

[danilius 117]

I use Taulman Bridge, and have so far failed to share my findings, so I'm going to make up for that now.

First of all, as @Ignatius pointed out, nylon is aggressively hydrophilic, so I have a kilo of silica beads, which I split into two. One stays with the nylon in a plastic bag, the other is kept dry in order to swap it out when the first lot is wet. I then dry the wet silica in the microwave (2 - 4 minutes until steaming hot, never, ever, ever, ever touch hot silica).

Secondly, I dry the nylon with silica in a plastic bag for at least two hours on a hot radiator.

When printing, nylon will bubble up even if completely dry, because it is very temperature sensitive. So, even though Taulman recommends 242C as a printing temperature, I print as low as 200C. I gauge the temperature by watching the nylon as it is extruded and listening for crackling. If it starts to turn into white foam and crackles, the temp is way too high.

Retractions are fine provided your feeder is really tight, so I use Robert's feeder and tighten the bolt up considerably.

Finally, I simply do not use the fan. When printing really small parts, I print several in one go, and keep them close to each other to reduce dribbling. Both 100 and 200 microns work well with Bridge, provided you up the temperature at 200 microns of course.

Like all filaments, it takes some experimentation to get it producing the results you want.

To get an idea of what you can expect from nylon, here is a part I printed at 100 microns:

Edited November 8, 2015 by Guest

[darkglove 3]

Thanks for replies.

I'm using Nylon 6 NYL-BLA 3mm

Maybe I should get some bridge as although I don't mind experimenting to get good results, I'm getting bored of printing failed test prints...

Sounds like I deffinitely do need to dry it out as it's been out of the packet and on my spool for a few days.

I'm not actually getting a lot of popping though, one or two here and there but not a lot at all. The reason I went with turning the fan on was that it just wasn't setting, could that be a moisture thing?

I have managed to get better prints by slowing the print down and increasing the extrusion amount (just a little) but I feel I am putting a sticky plaster on a broken leg.

My best effort so far of printing a vertical cylinder! Fail

[danilius 117]

Ouch, that look horrible. Drop the temperature considerably.

[darkglove 3]

I've dropped the material for now.

Worryingly I decided to try something else (I got some samples) but it's done something similar...

HD Glass with the temp down to 218.

Again, it starts off fine but around the same height as my first Nylon prints it's become a dribble twister!

[darkglove 3]

Yep, a temp drop really nailed the HD Glass print. I think I'm starting to get a better understanding of how the temperature effects the print.

Will look at that when I next do a Nylon print too.

I'll add to this post when I do.

Thanks

[danilius 117]

Here is a tip: when running into problems, print slowly (30mm/s) and sit by the printer and watch what happens. This will usually help to solve a lot of such problems.

[darkglove 3]

Thanks, that's what I have been but they always seem to spanner just as I leave the room!

Got some fantastic prints now using HD Glass... Not sure I need to go down the Nylon route for now.