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Lukephos

Filament not sticking with steel nozzle.

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Since switching to a stainless steel nozzle on my UM2+ I've not had a successful print. No matter what setting I've tried the filament will immediately curl up around the tip of the nozzle, gliding over the plate without a care. I have been able to get it to stick a little with some attempts but It does lift quite a lot and more likely than not if it has to retract when it starts again it will curl up. I've not been able to get past the first layer. I really don't know what it could be, I've tried different build plate heights, different temperatures for it and the hothead. I got more success with much lower temperatures but the filaments is meant for 220 to 240 degrees c and the build plate 75 to 85. It doesn't help that this is my first time using the filament too. Before switching nozzle I was still using the ultimaker filament, I switched to colorfabb ngen. Please help, it'd bloody annoying. (Sorry this is a repost, just figured it'd be better here rather than where I put it before. When one gets answered I'll delete the other.)

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Try with a ruby nozzle. Seem pretty solid to me even though might be a bit expensive for the casual user? Or a different kind. Is there a specific reason it has to be steel?

When I was looking at videos about things like wood or metal filaments they kept saying you need a steel nozzle to handle the abrasive filament since it's made with small beads. I didn't even know there where ruby nozzles. Either way I'd rather get this nozzle working, unless there's somehow something wrong with it.

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Heat conductivity of a steel nozzle is poor. For any non abrasive material like pla or ngen don't use it, switch back to a normal nozzle.

If you regularly print abrasive stuff, like metal filled material or glow in the dark, a ruby is a good idea. If you just try abrasive stuff you can also keep a normal nozzle specially for this material, but depending on the material it will not last very long.

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Heat conductivity of a steel nozzle is poor.  For any non abrasive material like pla or ngen don't use it, switch back to a normal nozzle.

If you regularly print abrasive stuff, like metal filled material or glow in the dark, a ruby is a good idea. If you just try abrasive stuff you can also keep a normal nozzle specially for this material, but depending on the material it will not last very long.

Ok, if I really get stuck I'll switch back to the brass nozzle, but I do want to get this nozzle printing. Sure it doesn't conduct heat as well but it shouldn't be making it curl up around the nozzle like that. I can't find any videos or posts about printing with them, so I'm guessing this isn't a common issue. Also no, I'm not spending that much on a ruby nozzle, that's overkill.

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..... or glow in the dark......

Would this include glow in the dark PLA? I have not seen this mentioned before.

 

Yep, glow in the dark is also considered abrasive.

 

Well, flapdoodle.....I did not know that when I printed some glow in the dark stuff. I have not done much, mostly to test it out on a couple of prints. But when you purchase this stuff, they do not tell you. I went and looked at product pages and nothing was mentioned.

I assume it is not as abrasive as the other stuff, Carbon Fibre, Metal filled, etc?

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I'm sure there are different levels of abrasives, and some are worse than others. And I'm sure glow in the dark doesn't rank that high but still. Do a quick google search about Glow in the dark filament abrasive and the results will tell you :)

 

I did do a google search and though it is mentioned, it is not specific and I still think the manufacturers need to come up with an abrasion scale so that it can be weighed or just even mention it. I did the search after I did not get a reply for a day or two after I got a bit of a break.

The worst is that (according to the searches I did) it varies due to the type of material used and how fine it is ground.

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To prevent curling up, have you tried wiping the nozzle with a tissue moistened with silicon oil? And/or with PTFE oil?

This reduces build-up of molten filament on the nozzle, but it also reduces the tendency to curl up when priming the nozzle. So it might help during the print too?

If temp conductivity of a steel nozzle is much worse, maybe you could try increasing the temp by 10°C, and see what happens? If the filament is too cold when exiting the nozzle, it also won't stick well.

Further: did anything change on the glass plate? Different glue, different preparation or cleaning, different climate conditions (e.g. moist weather),...? In the very beginning I also had this problem in moist weather, especially after cleaning the glass plate with window cleaner: then nothing would stick. Now I only clean with pure warm tap water (no soap, no additives), and then I wipe the glass plate with a tissue moistened with salt water: this seems to increase surface tension and greatly improves bonding of PLA. For other materials (polyester, PET) gr5's method with dilluted wood glue works well.

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I think I figured it out. Remember how I said I used the recommended temperatures for the filament? Well it turns out the build plate temperature was actually pretty low for said material. Upping it (all be it to its max recommended) has fixed it. So I guess the nozzle was unrelated then... huh. One thing I do have to ask, and though I am testing with it some advice would be great, how should I tune the temperature for the best stick? The print I'm trying to has some very thin unconnected rims, and there's always some that lift and ruin the first layer. I don't know if I have things too hot or cool, so any tips would be great. Also ways to keep the pre print extrude filament out the way, that's pretty annoying.

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What kind of material did you have again?

Heat is one way of improving adhesion but there are other methods as well. Don't print too fast, print your first layer rather slow. You can also use a thin layer of glue as extra and we also have adhesion sheets, which also stimulate extra adhesion. Depending on which filament you have, applying one of these tips could help you get a solid and reliable first layer.

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The bed temp should be around the glass transition temp of the material: that is the temperature where it begins to soften and get flexible (which is very long before it is melting). For most PLA this Tg is around 55°C, if I remember well.

If you print PLA on bare glass, after wiping the glass with a tissue moistened with salt water, then the effects are as follows on my system:

- no heated bed: model does not stick at all, extruded sausages curl up and come off immediately,

- bed temp way too cold: printing starts fine, but model pops off suddenly during print,

- bed temp a bit too cold: corners lift due to insufficient bonding,

- bed temp good: no corners lifting, PLA sticks like glue (at least for Ultimaker and colorFabb PLA, some other brands stick a bit less),

- bed temp too high: whole model stays too soft, and corners lift due to the model being peeled off the glass. Also: model sags and gets severe "elephant feet".

Different bonding methods might give different optimal glass temps.

So, your best option is to design a test model, for example a ruler of 1cm x 1cm x 10cm, laying down (not vertical), and 100% filled. Then start with the bed at the Tg, and then try steps of 10°C above and below this.

If you want an even more critical test model, try an inverted prism: a small base of 5mm wide x 30mm long or so, and a wide top of 15mm x 30mm. This gives huge warping forces on a very small bonding area.

To prevent the primed "sausages" from being pulled into the print, I use a plied piece of steel wire around the priming area. It is inox spring steel (like used in bridges in the mouth), so it lasts forever. It is a metal version of the 3D-printed "filcatch" idea of another user here (I can't remember any names...).

steel_filcatch1.thumb.jpg.2b3e229fdf742ed53c4aae4fd1e2016d.jpg

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