Rough nylon prints

[Travis7s 25]

Hello all,

I am pretty much a 3D printing novice but I am in charge of an UM3 for my work. We just received it this week and we primarily want to print in nylon but I have never really got a print to the point that I like. The prints are very "scabby" and rough. I thought it may have been a levelling issue so i disabled active leveling and tweaked it manually. This seemed to work great for the first half of my print but then it went back to its scabby ways. (see photos)

Cura 3.2.1 with default setting for UM Transparent Nylon and 0.2mm layer. I updated the firmware yesterday as well although I can't recall the version off the top of my head. I also have the Printed Solid enclosure/door kit installed.

The other thing I am worried about is the nylon-moisture issues, is that something that could cause this type of issue? I opened the nylon filament on Monday and have not taken any steps to dry it out. (humidity is quite low here in Saskatoon right now however)

Any help would be appreciated, thanks.

Edited April 5, 2018 by Travis7s

[Coalwater 1]

I'm also having issues with nylon. It gets all smudgy and I can't seem to print a clean part, especially small ones like 2mm diameter pins. I also have the Printed Solid enclosure. At first I thought the enclosure made the ambient air too hot but I'm, not sure yet. To me it looks like I can't get the nylon to cool fast enough between layers. how big is your part? You should be able to do something by playing around with print speed, minimum layer time, etc...

 

Here's how my latest test turned out...

 

[kmanstudios 1,120]

4 hours ago, Coalwater said:

I'm also having issues with nylon. It gets all smudgy and I can't seem to print a clean part, especially small ones like 2mm diameter pins. I also have the Printed Solid enclosure. At first I thought the enclosure made the ambient air too hot but I'm, not sure yet. To me it looks like I can't get the nylon to cool fast enough between layers. how big is your part? You should be able to do something by playing around with print speed, minimum layer time, etc...

 

Here's how my latest test turned out...

 

This will usually happen when the print does not stick properly and gets wound around the nozzle. Also, Nylon is very moisture sensitive. Not PVA sensitive, but you should always keep an eye out for cracks, pops and sizzles.

 

9 hours ago, Travis7s said:

Hello all,

I am pretty much a 3D printing novice but I am in charge of an UM3 for my work. We just received it this week and we primarily want to print in nylon but I have never really got a print to the point that I like. The prints are very "scabby" and rough. I thought it may have been a levelling issue so i disabled active leveling and tweaked it manually. This seemed to work great for the first half of my print but then it went back to its scabby ways. (see photos)

Cura 3.2.1 with default setting for UM Transparent Nylon and 0.2mm layer. I updated the firmware yesterday as well although I can't recall the version off the top of my head. I also have the Printed Solid enclosure/door kit installed.

The other thing I am worried about is the nylon-moisture issues, is that something that could cause this type of issue? I opened the nylon filament on Monday and have not taken any steps to dry it out. (humidity is quite low here in Saskatoon right now however)

Any help would be appreciated, thanks.

Moisture was addressed above. But you can always change your layer thickness from the defaults. Also, adjust temps, speeds, etc. I suggest making a series of small cylinders and cubes just to do this as quickly as possible. Also, remember, not all nylon is the same. For nylon, so far, I have enjoyed the UM Nylon the most.

 

For long term drying issues, you may want to build a drybox or get the Polybox. This will be very important as your humidity builds up and may be using PVA (Much more moisture sensitive) and Nylon.

 

The dry box builds are aplenty out there on youmagine and thingiverse.

[yellowshark 153]

Yes as @kmanstudios says nylon is very hygroscopic; this is one of the key features of getting a decent print. It is a bit like bed-levelling, you think it is level but it is not. If it is really wet you will see/hear steam and hissing coming from the nozzle, but... (it has been a couple of years since I printed it) but I think I nearly always put it in the oven to dry it first. This is not recommend (by me) unless you know what your are doing with temperatures. I once put two different nylons in the oven and wrecked one because it had a lower melting temp. And I always stored my nylon, with desiccant, in what we call the "airing cupboard" i.e. housing the hot water tank.

 

Again as @kmanstudios says all nylons are different but two other key aspects are print slow and print hot (i.e. hotter than PLA). I used to print my Taulman nylon at 20mm/s to 30mm/s and up to 245 plus depending on layer thickness. BUT you need to do some simple testing to determine the correct settings for you and your nylon; otherwise you are going to waste a heap of time and material! Oh and unless you at printing a very small piece you should try turning your fans off; this is a Taulman recommendation but whether that is best for all nylons I know not.

[geert_2 557]

I have no experience printing nylon. But from the specs it is known that in only 3 hours it can soak up enough water to make it unsuitable for injection moulding. So, the same will probably apply to 3D-printing. If you look at a printed nylon sausage under a microscope, you may see bubbles inside the material, or craters on the surface (=popped open bubbles). So using a method to keep it dry even while printing, is best. (One of the drying boxes available.)

 

But if you are totally new to 3D-printing, I would recommend that you first print a few weeks in an easy material like PLA. Just to get to know the machine and the whole process. And only when you know these quite well, switch to a difficult material like nylon.

 

It's like driving: you don't want your first driving lesson in rush hour in the center of Paris, in a big truck. You want a calm moment on a safe calm street, in an easy car. And gently progress to more difficult situations, as you master the easier ones. 

 

[yellowshark 153]

Lol yes you probably never want to drive in Paris with a big truck! I had been printing for about 2 years before trying nylon and it certainly came as a shock after all those nice and easy PLA prints! I always struggled to some degree although I believe the some of the newer nylons such as Bridge are much easier.

[Coalwater 1]

9 hours ago, kmanstudios said:

This will usually happen when the print does not stick properly and gets wound around the nozzle. Also, Nylon is very moisture sensitive. Not PVA sensitive, but you should always keep an eye out for cracks, pops and sizzles.

 

Yes, I read about that. I've been keeping the reel in a resealable bag with a desiccant pouch in it but I'm building a dry box now... Is the oozing because of moisture also? I was able to get something decent with an ooze shield, but I had to print 2 parts with 2 different materials for it to work.

 

Edited April 6, 2018 by Coalwater

[kmanstudios 1,120]

21 minutes ago, Coalwater said:

Is the oozing because of moisture also?

That sounds more like a temp issue to me. Start off with quick objects as mentioned to fine tune those settings.

[Coalwater 1]

I suck at forums... I don't want to hijack this thread, should I start a new one about nylon printing issues in general?

[kmanstudios 1,120]

Why? This is will create a larger thread count about the same issues. And, you may help the OP too. I am not a Mod though, so my opinion merits little consideration....just throwing it out there.

[Travis7s 25]

My print is relatively small, its 1" tall for reference.  I am making some progress by tinkering with settings but I was hoping the UM3 would have been a lot more hassle free. My CR-10 mni at home has worked a lot better although I have only been doing PLA. My UM3 crashed the plate right out of the box with its active leveling and I already had a major glitch where the printer "froze" at the beginning where it moves to the front left side and deposits a  bunch of filament to clear the nozzle. It ended up stuck there flooding its nozzle with a puddle of filament, couldn't even abort the print with the display, had to kill it with the power switch.

I'm going to try some more prints today so we will see how it goes. I don't mind if you use this thread for your own problems.

[gr5 2,167]

It took me about 100 prints to get really good at PLA.  It took me another 50 to get good at Nylon.  There's a lot of lessons to learn.  Nylon is even harder to print than ABS.  But it's very rewarding as it has great properties.

 

All of the photos above look great as far as water absorption - I don't think that's the problem.  If it is you will know it - for one thing, you can hear it sizzling and popping as the water boils.  Also, the clear filament looks snowier and the black will look more matte.

 

The person printing those small black things - enclosure is good for nylon.  Use it.  But you *might* have a cooling issue. Maybe. In fact, if everything you print will be under 5mm tall you don't need the enclosure as the air there is fine that close to the glass.  The best way to print a part that small is to print 3 of them at a time.  That way one can be cooling while you print a layer on the other two.   Print them lined up on the x-axis so the fans reach them better.  This is "pla" advice and I'm not sure it applies to nylon as I haven't printed things that small in nylon.  

 

Also, your black parts aren't sticking well it looks like.  You might want to raise the temp of your glass.  80C should be enough.  100C should be fine.  The most likely problem is you didn't squish the bottom layer enough.  I am not a fan of active leveling - if you do normal manual leveling and then turn the 3 leveling screws about 1/3 turn looser (glass closer to nozzle) you'll probably get about the right amount of squish so your part sticks to the bed.  And use an extremely thin layer of glue - this video shows you how to apply glue.  And how much to squish your filament to get it to stick well:

 

[Travis7s 25]

I will say I am using the supplied glue stick with my nylon and it works great. Without it I would get warping and sometimes the print would break loose. My glass has always been set at 60C.

 

 

[Coalwater 1]

All good points, thanks!

 

If I can solve the oozing problem, I think I'll get what I need. The best success I've had so far is with an ooze shield but since it's only available in dual extrusion I had to print 2 parts, like you suggested, but the only material I have on hand is PLA and it don't mix with nylon so the ooze shield eventually collapses.

 

50 minutes ago, Travis7s said:

I will say I am using the supplied glue stick with my nylon and it works great. Without it I would get warping and sometimes the print would break loose. My glass has always been set at 60C.

 

I've been using 3D lac instead oF the glue stick and nylon sticks well most of the time at 60C. It depends on the shape of the part. I'm trying it at 80C now.

Edited April 6, 2018 by Coalwater

[yellowshark 153]

Lol you see we are all different. I print PLA with a bed temp of 65 but I go lower with my Nylon not higher, about 50.

 

To both of you, just to stress this but it has been mentioned. You are both printing very small pieces. Do you have your minimum layer time set to say 10 seconds? I know I said above possibly not to use fan with nylon but your stuff is so small maybe you have no choice. As @gr5 says the normal solution will be to print multiple copies "all at once", an odd number and the middle one will be the best. You must get your last layer cool before printing the next one and that is not always easy on stuff this small

[Coalwater 1]

14 minutes ago, yellowshark said:

Do you have your minimum layer time set to say 10 seconds? I know I said above possibly not to use fan with nylon but your stuff is so small maybe you have no choice.

 

I tried. The print head moved away from the part and the nylon strings between the nozzle and the part. It makes quite a mess... I also tried reducing the print speed a lot. It didn't help.

Edited April 6, 2018 by Coalwater

[Travis7s 25]

 I am already seeing drastically better results today. I have been playing with the wall thickness settings to better match my 0.4mm nozzle. It seems a big problem is if the printer has to rapidly jog back and forth to fill gaps, if I eliminate this the blobs go away.

[yellowshark 153]

Well I would leave it at 10 seconds and add more copies - once it stops moving away you know you have enough copies on the bed. If it was PLA I would say the filament should not string when it moves away, i.e. if it does you have a setting wrong somewhere, but I have never printed that small with nylon and so would not like to make a similar comment as I have never experienced it.

[yellowshark 153]

1 minute ago, Travis7s said:

 I am already seeing drastically better results today. I have been playing with the wall thickness settings to better match my 0.4mm nozzle. It seems a big problem is if the printer has to rapidly jog back and forth to fill gaps, if I eliminate this the blobs go away.

Well fwiw in my book and I know others disagree!, but if you do not match your nozzle size you are just asking for trouble so why do it.

[Travis7s 25]

I guess I mean I am tweaking the actual mechanical design, but I don't always have control of these. If someone design a part with 1mm thick wall the slicer will have to make compromises to get it right with a 0.4mm or 0.8mm nozzle.

[yellowshark 153]

11 minutes ago, Coalwater said:

 

I tried. The print head moved away from the part and the nylon strings between the nozzle and the part. It makes quite a mess... I also tried reducing the print speed a lot. It didn't help.

 

Your filament supplier should have published recommended settings somewhere - if not find another supplier! Everything I have read has nylon printing at lower speeds- but this will be filament dependent to a certain extent - it may be that printing really small stuff with nylon is incompatible. I do not print small stuff normally (and never with nylon) and I think I read that with small you may need to go faster otherwise the heat of the extruder dawdling over the small dimensions can cause problems. This is why getting the recommendations is important because my comments come from only experience with Taulman.

[Travis7s 25]

What kind of speeds are considered "lower"? By default Cura sets UM nylon at 70mm. I also tried at 35mm but didn't really see any difference.

[yellowshark 153]

3 minutes ago, Travis7s said:

I guess I mean I am tweaking the actual mechanical design, but I don't always have control of these. If someone design a part with 1mm thick wall the slicer will have to make compromises to get it right with a 0.4mm or 0.8mm nozzle.

Well I normally print my own designs and they are designed to a .4mm nozzle but If I were printing somebody else's I would still set the line width to 0.4mm and let the slicer use infill. But each to their own 

[Travis7s 25]

Yeah, it just seems like thats the problem for me right now. Infilling thin gaps with nylon seems to cause it blob over the edge.

[yellowshark 153]

Just now, Travis7s said:

What kind of speeds are considered "lower"? By default Cura sets UM nylon at 70mm. I also tried at 35mm but didn't really see any difference.

Depends on who you are talking to! I would consider 35mm/s to be on the borderline but maybe UM have designed their nylon to be printed at 75mm/s.  Do you have any recommendations from them on the packet or the web. Not that I use them but I have seen UM standard settings that amaze me - not in a good way. Lol I have never printed anything at  75mm/s let alone with nylon. And imho 75mm/s is too fast for something that small, in terms of getting a decent finish. The rule for good small stuff is slow and cool; as I said earlier it could be that really small and nylon are incompatible, although Taulman recommend 25mm/s maybe slower for their older nylons.