Extruding Nylon

for the warping issues...

try a lower temp in extrusion and bed temp. nylon Glass transition temperature: 50C. [www.polymerprocessing.com]

abs glass transition temp 100C-110C (from memory no web link, sorry)


IMHO
so the reason the part is warping, is it is folding not warping. try a heated bed temp of 40-60C and lowering extruder temp. the base of the plastic is folding from all the pressure and weight of the top and the extrusion head. it is OK for first layer to be in a glass transition state but the layers above, must cool and become hardened below 50C

Edited 2 time(s). Last edit at 05/25/2011 05:24AM by jamesdanielv.

The reason for warping is because hot plastic is being laid down on top of cold plastic. As the hot plastic cools down, it shrinks and in the process pulls the cold plastic below it. By heating the bed, we keep the plastic in the base layers above the glass transition temperature (Tg) to prevent them from shrinking before the upper layers. This only partially solves the problem since the heated bed can't keep the whole part above the Tg as the part gets taller. When the part gets tall enough, the bed is no longer effective in keeping all the layers above the Tg and it now starts to warp. But if the base layers are stuck to the heated bed, it minimizes the effect of the shrinkage. The pulling force concentrates on sharp corners so it usually comes off the bed in those areas first. The pulling force is also larger as the part gets larger in the x-y direction, so larger parts will warp more than smaller parts. The full solution is to heat the build chamber to ensure that the whole part stays above Tg during the build process and then cooled down uniformly.

The bed ./ chamber keeps the plastic just below Tg, not above it. I.e. low enough to make it hard, but not contract further. The contraction from Tm to Tg then does not cause warping because the solid layer below is rigid compared to plastic above Tg.

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[www.hydraraptor.blogspot.com]

Just a thought on this subject with every one talking about re-use of Gardening nylon from garden strimmers/weed wackers.

I have not seen any mention of using Monofilament (Nylon) fishing line which acording to this link is extruded [en.wikipedia.org]..

This could be mean very low presure extruders with Nylon fishing line being avalible Like this:-

Favourable nylon monofilament fishing line diameter from 0.1mm to 0.5mm ,100meters

With Nylon fishing line being this diamiter alredy it could be dryed prior to printing in a small in line drying box.

I think the extyruder drive could be as simple as compressed rubber rollers feeding into a very small heated extruder tip.

Looking through the various diffrent types of fishing line it may be some of the many other polymer combinations used as fishing line could also be printed.

I guess that 3D printing has not yet got much of a following within the fishing comunity yet else some one who has fishing as a hobby would have sugested this as a posibble print material.

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I'm not sure you could force .5mm filament into the extruder without it buckling.

Hi I have just stumbled upon your thread. I have been using ABS on my rapman, but it is not an engineering plastic, and the ABS parts wear out very quickly when used for wheels, etc.

But printing any one of the nylon grades or PBT will most definately crack rapid prototyping into the rapid production game. Nylon absorbs moisture and has to be dried even prior to injection moulding. If it is not dried before moulding the moisture simply boils into steam that reacts to form bubbles, but it also reacts with the Nylon to significantly degrade its properties.

One benefit is that nylon is Crystaline and has a relatively sharp solidifying curve, which means that if it were to be printed in a oven that is held relatively close to to the extruder temperature, the part warpage would be 10 to 50 times less than that found with ABS. The same would apply to Acetal which is a very stable and also a crystaline plastic.

Nylon is currently being printed in EOS laser sintering machines, and they definitely don't wait 1.5 minutes between layers, and the cooling requirement is similar to extruding and cooling the melted filament. But FDM could very different... for some unknown reasons.

How is it going with your nylon extruding experiments, and where could I get more information on it?

I think Nylon is the next big material or at least the material that could move FDM from prototypes to production parts, if needs be, I will set up a mini extruder with 2nd hand parts to make filaments.

There are currently no 'real' heated chambers in reprap that I know of, and Nylon has dismal warping using current practices used for ABS and PLA.

I think Polycarb is the next material step the community will take, since it has more similar printing properties to ABS.

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www.Fablicator.com

Just wanted to update this thread. I just saw an instructable on how to print with Nylon here:
[www.instructables.com]
The results look amazing. I hope more people try this as it looks extremely useful.

Yes I asked him a couple of questions but he didn't answer:
What exactly is a four orifice extruder?.[www.thingiverse.com]
How does he manage to use PTFE at 420C.

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[www.hydraraptor.blogspot.com]

The warping and curling issues with Nylon can be fixed by printing with a brim!

Check out my post on printing with a "brim" here: [forums.reprap.org]

I print with a 1.7mm filament and have a 0.3mm nozzel.

I am in the middle of moving right now, but I would love a sample of the "printable nylon" filament. I bet I can print with it and defeat warping with the material as well!

Would anyone be willing to send me some once I am in my new home in California? (one month from now)

I bet I can come up with a mostly software solution to make the nylon printable

No one mentions toxicity of melted nylon off gassing?

@idol
You can get some very cheap at your local hardware store. The equivalent size is 0.105 in, which is pretty common. If you want bulk, go to

[www.amazon.com]

I just got a roll and I am trying to get it to stop warping myself. I think I will need to print with a brim on perfboard. That might be enough to hold it down. Either that or I print on a sheet of Nylon, but I think that will weld right to it. Maybe a different type of plastic will only semi-stick to it. I will keep trying. It would be nice to have someone else working on it.

@wild

If you keep the trimmer line below 300 C, there will be no off gassing. I am printing the weed trimmer line at 230 C currently. It doesn't actually weld together, but the adhesion is so strong that it might as well be welded. The parts I make with Nylon are much stronger than ABS, albeit warped.

galaxyman please stop spreading nonsense. There is nylon off gassing even at 230C. What you are doing is extremely dangerous and your misinformation is putting others at risk.

On the contrary, here is the MSDS sheet for Nylon. It states that thermal decomposition occurs at >300 C

[www.directplasticsonline.co.uk]

Not taking any sides as I am interested in Nylon myself but if it is melting wouldn't a gas also be released?

Edited 1 time(s). Last edit at 07/24/2012 08:04PM by Dark Alchemist.

Dark Alchemist Wrote:
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> Not taking any sides as I am interested in Nylon
> myself but if it is melting wouldn't a gas also be
> released?

Possibly, but not necessarily decomposed gasses, which are the problem. Hydrogen cyanide is not an ingredient in nylon, but can be produced if it is heated excessively. Assuming that MSDS is correct, and that the nylon formulation you are using matches it, I don't see an issue with printing nylon as long as you are sure it does not get above 300*C.

Personally I would use some form of fume extractor though, and use it in a well-ventilated area until it is known for sure what the by-products of extrusion are.

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No reliable sources with MSDS data to match their product.

Dark Alchemist Wrote:
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> No reliable sources with MSDS data to match their
> product.

That's the problem.

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As I lay there dead in a heap the Ambulance crew will take my corpse to the hospital but before I am fully loaded on the gurney one EMT will look at my table and say 'Damn, that is one nice print he made before the gas got to him.'

Yeah, on my Tombstone you could print that.

The msds for hydrogen cyanide says that it produces throat and eye irritation. So first of all, if I experience those symptoms I will definetly be more careful, and second, it is only toxic in very large doses, like when firefighters go into a burning building. I am not saying it's not bad stuff, just that you are not likely to be affected by it in such small doses, and there are plenty of warning signs. If you want to be careful, just have a fan that blows the fumes out the window or something.

There are risks with nylon that are not present with the other plastics. The concern expressed here is simply to ensure you've educated yourself (which you obviously have), and are sufficiently safe. The concern is also expressed for others who might be reading this thread. The last thing any of us want to hear, is that someone hurt themselves because they weren't even aware there were additional risks with extruding nylon and therefore didn't take proper precautions.

That said, you really don't want to wait until symptoms manifest as your way to measure exposure. Damage may (will?) already be done. You might not die, but you might never fully recover either. So, error on the side of caution and stay safe while you push this technology. Personally, I'd need some sort of fume containment and removal (e.g. a fume hood equivalent) to feel safe.


'nuff said.

Well I found a solution to the warping . What I did is put a square of sheet metal over my heated bed, then I used the "brim" setting in slic3r with 15 loops. I then placed small magnets all around the "brim" after the first layer finished. This keeps the part nice and flat, with no warping evident, even with large parts . Now I just need to work out the oozing problem. On long travels, the ooze makes a big difference, and makes a bunch of nasty globs all over the side of the part. I have my travel speed set at 600 mm/s, so that the nozzle will ooze less while traveling, and I have a retract of 1 mm. If I turn up the retract, the nozzle stays in the same spot for too long and creates a blob. Is there a way to make the extruder retract while it is traveling? I am using pronterface with slic3r.

Ok I have the retract at 7 mm, and it seems to print quite well. There are still small strings, but those can be burnt off with a lighter or cut off. I turned the bed temperature up to the max my bed could handle, 120 C, and that reduced warping quite a bit. I also added the brim plus the magnets ect.

I did find out something interesting while printing with the stuff. If you have even a small amount of water absorbed into the line, it will create pockets of steam that disrupt the flow of filament. If this creates even one defect, it will ruin a couple layers above that too, so the part will snap at that point very easily. This is especially true for thin walls. Before I thought that the layer adhesion was just weak and I needed to turn up the temperature, but it turns out it is actually these defects causing the weakness in the part. Therefore I would need to keep the filament very dry, with a tube for the filament to the extruder.

The other option is to purposley allow the filament to absorb water, so that the extruded material is foamy. This happens when you print at around 30 mm/s or up. The speed of extrusion doesn't allow the steam to escape the filament. However, this will ultimately lead to more inconsistent prints with poor surface finish. However this means I don't have to keep the filament in an airtight container with dessicant. It also means that the prints will use less plastic due to the plastic expanding so much.

I will try soaking some line in water and see if that gives me a consistent foamy extrusion.

so no matter dry the nylon? but even it you get immersed in the water?

Ok I tried soaking the filament in water, and that pretty much came out like expected, a total mess. The print was super inconsistent and weak.

I dried the filament for another hour and that seemed to make it work much better. I also stored it in a bag with some dessicant you can get for keeping closets dry and I think that is helping too. Now I am getting perfectly smooth prints with no defects that make it weaker. One down, two more to go.

I have a couple more problems that need sorting out:

1. The blue tape I use on the heated bed isn't sticking well enough at 120 C. I think the temperature is making the tape not adhere. I am wondering if kapton tape will stick better at high temperatures and if Nylon will stick to it. One interesting thing about Nylon is that it sticks like glue to printer paper, so if I could find some cheap tape that sticks well at high temperatures and has a similar backing, that would solve my warping problems.

2. The nozzle drags through the print. I think this is actually what is causing the strings. It could be because of the nozzle shape that I have, or that the first layer is overfilled, which makes a bunch of blobs stick to the nozzle and screw up the rest of the print.

So far I have had great results, which are getting better every day. The layer adhesion is getting better with higher printing temperatures and drier filament. I will post some pics soon.

Ok, so I have some weird results. I measured the trimmer line, and it was 2.65 mm consistently. However, when I extrude it, I have to use an extrusion ratio of 0.5 or the part is way too overfilled. I don't know if this is a glitch in slic3r or pronterface or if Nylon just expands a lot. Anyways, with the ratio set at 0.5 it is printing very high quality with no stringing.

I still need to find something with a paper like backing to use as a bed. I could use squares of cardboard, or cardstock, cut to size and inserted underneath the heated bed screws. I am not sure how well this will prevent warping. I guess it depends on how stiff the cardstock is. Also, it is a little costly to keep replacing. Maybe Nylon will stick just as well to wood, possibly MDF. Not sure how easily that will transfer heat though.

If anyone has any ideas for a permanent solution, that would be great

what temperature do you extrude?

When extruding HDPE, which is similar to nylon in that it is slippery and very hard to glue, I found that the only thing it would stick to was itself, or other types of PE. See [hydraraptor.blogspot.co.uk]

Perhaps you could use a sheet of nylon as a bed. Extrude the first layer a little high to make a weak weld that can be peeled.

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[www.hydraraptor.blogspot.com]

@ifala
I extrude at 245 C, which is the limit for my PEEK insulator. My bed temperature is 120 C.

@nophead
I have tried that, and I ended up welding a part right to the bed. It was very hard to get it at a height where the Nylon would stick the right amount.

I tried printing on cardboard, and that worked quite well. I tested a long skinny piece and saw no warping at all. I am not sure how long the cardboard will last, but it is looking good after 1 print. I will try some more and post some pics.

I bet the cardboard is acting like a sponge and helping.