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johnse

Nylon thick stringing at all temps

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Posted · Nylon thick stringing at all temps

I'm still fairly new to this but I've started printing with Nylon for some pieces. I'm using Ultimaker Nylon (natural) using the default profile--typically at .1mm, sometimes at .15mm layers (AA 0.4 printcore).

 

I get a lot of thick strings/nubs on the parts whether I'm printing with or without support material and whether using PVA or Breakaway support. I also notice occasionally a brown color to the nylon--often on the prime blob.

 

I thought I might be printing too hot, though the standard template for .1mm layers uses 245C. Last night I printed a temperature tower running from 255 - 220 in 5 degree steps. 255-240 printed successfully--but with lots of the thick strings. 235 started to print but broke off midway through the layer and then it was just a cloud of filament-on-air... So definitely cannot print below 240 degrees :)

 

The top of the anvil is where the 235 section broke off. I'm not worried about that. It's all of the thick strings throughout the tower. It's a little hard to read the temps, but they are 240, 245, 250, and 255 top-to-bottom. Also notice in the overhangs you can see some of the brown discoloration at several levels.

 

These nubs have to be cut off which is a pain especially on some threaded parts. They also often get embedded in support material and vice versa. Breakaway tends to like making little curly cues that break off or get embedded in the part material.

 

Do I need to play with retraction? More/less cooling? I keep my filament in a dry box except when printing (planning to make a print-from-dry-box setup) but as you can see from the brim, the filament goes down nice and clear. I saw some other posts talking about oozing between material changes, but I get the same issues whether I use a prime tower or not, and of course the temperature tower was printed by itself with no support.

 

nylon-tower-1.jpg

nylon-tower-2.jpg

nylon-tower-3.jpg

nylon-tower-4.jpg

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Posted · Nylon thick stringing at all temps

I don't see any stringing - or barely any.  Your retraction looks good.

 

Maybe what I call "bridging" you call "stringing"?  Bridging is where you are bridging across an air gap.  Yes your part doesn't look great there but that's probably the best you can get with Nylon alone.  If you had a dual nozzle printer, PVA works very well with Nylon.  But I can't help you on the bridge settings - PLA is the nicest material for bridging and even PLA won't get much better than what you got.  Usually.

 

Although @smartavionics has a version of Cura that lets you play with a lot of the bridge settings.  You could try that version of Cura - search for "bridge" in the settings.

https://www.dropbox.com/sh/s43vqzmi4d2bqe2/AAADdYdSu9iwcKa0Knqgurm4a?dl=0&lst=

 

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Posted (edited) · Nylon thick stringing at all temps

I'm not talking about the bridging. I'm talking about all of the little spikes protruding from the vertical parts.

 

Here are some closeups with the areas circled.

 

I noted in the tags, but didn't mention in the text that this is being printed on an Ultimaker 3. And I get this whether I'm using support material or not.

1612375726_close-upnylon1.thumb.jpg.3daaaf72316ac9736af189b1ef603211.jpg422122366_close-upnylon2.thumb.jpg.017bf085b87a5f66d244cc70f7280845.jpg1510046705_close-upnylon3.thumb.jpg.b4a570ec2b6f710c02945e6c710cad79.jpg1187298727_close-upnylon4.thumb.jpg.dcf9ad7fd3347fa1024ad5e24d69e25e.jpg

Edited by johnse
Added being printed on UM3

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Posted · Nylon thick stringing at all temps

The little "insect antennas" are when the nozzle leaks a little bit while traveling through the air. Upon arriving at the next wall, that droplet is deposited on the side of the wall. On the next layer, the drop is deposited on the previous drop, since that is now what the nozzle encounters first after flying through the air. And so on..., causing upwards tilted "insect antennas".

 

I haven't printed with nylon yet, so I can't give any recommendations. For PLA, usually printing slow and cool helps, but I don't know how that would work for nylon: it might negatively affect layer-bonding. Increasing retraction also might have other side-effects. I would first try the slow and cool approach on a test-piece, where the "slow" is to prevent excessive pressure in the nozzle, and the "cool" is to make the melt less liquid and thus less likely to leak.

 

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Posted · Nylon thick stringing at all temps

Thank you. That gives me some directions to attack these antennae.

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