Acceptable Level of Filament Grinding

[Sukey 2]

Hello Ultimaker Experts,

We're trying to fine-tune our new Ultimaker 2 and have a question (or 10).

First up: Should the feeder be putting little nicks in the filament? It isn't grinding major divots, but is texturizing it for the full length. I read up on filament grinding and can't figure out if this denting is normal. The visual troubleshooting guide http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#grinding identifies the major divots as a problem, but isn't clear as to whether we should be expecting the small ongoing pattern, similar to what it shows before getting to the major divot.

We're having some difficulties printing, particularly with ABS, and so I'm working my way through possible problems/solutions.

Thanks for any and all help!

-S

[gr5 2,172]

ABS is much harder to print - you usually get very weak layer bonding and also it's common to have problems with the part not sticking to the glass. Also when you switch back to PLA it will really suck. I don't recommend switching very often but sticking with one material for all of your prints forever if possible. However many people switch back and forth but this adds more things you have to learn about if you switch often. The UM2 can print perfect ABS prints every time but there are some key things you need to know.

If you print only ABS then I recommend getting the IPM coupler from 3dsolex.com otherwise your teflon isolator probably won't last more than 200 hours of printing.

Anyway to get to your question - the filament on the left has insufficient spring tension. The filament on the right is perfect.

[IRobertI 520]

edit: George beat me And we disagree a bit about the image it looks like. Take the middle road of our replies

"Bite marks" in the filament is normal and expected. Without seeing a picture it's difficult to tell you if they are too big or not though but I doubt they are. Here's an image showing some bite marks:

The ones on the left are fine, maybe a bit too shallow. The ones on the right are a bit too aggressive. As you can see the feeder is almost flattening the filament, this can cause feed issues as the filament might become to fat to fit through the system.

Edited September 1, 2015 by Guest

[neotko 1,417]

If the filament make 'bites' and the cylinder form changes, doesn't that affect the effective mm/s of filament mm3 moved? There's room on the bowden for deformation but also there might be a point where the 2.85 diameter changes to something bigger since it deforms to an oval and. Doesn't that make trouble when going to the ptfe and scratching the ptfe? Just wondering out loud.

And to stay on topic I like very much the opinion on https://0x7d.com/2015/01/a-guide-to-high-quality-3d-prints/ about the filament extruder and filament bites.

Edited September 1, 2015 by Guest

[ultiarjan 1,223]

And regarding the switching between ABS/PLA, I guess it doesn't hurt to use the "olssonblock" so you can change nozzles, and keep separate nozzles for ABS and PLA ...

[Sukey 2]

Thank you all so much! It looks like the problem isn't in the feeder, given your guidance.

Here is what is happening: When using ABS, when we stop a print (pause OR finish one print and move on to another with cooling in between OR finish one item on the print bed and move to another item on the print bed without cooling in between), the nozzle clogs when printing the next item or resuming printing. Sometimes it is a total clog (no filament extruding), sometimes a partial clog (a bit of filament sort of extruding willy nilly usually sideways). Going through the filament replacement process solves the problem (sometimes supplemented by cleaning off the nozzle if it was a total mess). However, when it prints again, the first few minutes will print yellow (burnt). Even when you replace with the exact same filament that was in there before, and the filament is white going in, it still extrudes burnt for a bit. And the area right above the print nozzle also smokes a bit during printing, so I'm guessing it has something to do with heat.

Question 1: Any suggestions?

Question 2: We had hoped to move between filaments (part of the reason for purchasing the Ultimaker). You seem pretty adamant that I shouldn't move back from ABS to PLA, at least not with the same nozzle. Why? What are you anticipating/suggesting?

Note that we have access to a MakerBot, so can print PLA elsewhere if needed, but one of the reasons for getting the Ultimaker was to have ABS and HIPS as an option.

Thanks

[neotko 1,417]

If you change from a plastic (abs) to other (pla) you must (really must) do Atomic pulls to clean the nozze of that fiament before going to other because they work at different temperatures and work different. PLA burns (brown) at 240ish (or if not moving for sometime at 230+) and that burned pla will clog the nozzle hard if not cleaned. ABS don't flows at PLA temperature so it will also clog the nozzle if traces of abs remain there when doing pla. Etc etc. this happens on any 3D printer.

It's not an issue not to change nozzles, but if you do you can avoid the atomic pull and if you get use to it save time. But it's time non the less.

Edited September 1, 2015 by Guest

[Sukey 2]

@neotke - I did not do Atomic pulls (https://ultimaker.com/en/support/view/149-atomic-method) when I moved from PLA to ABS, so thanks for the guidance. The atomic method info says to heat the nozzle to 260, but that would burn PLA, so if I was moving from PLA to ABS, should I have cleaned it by using PLA still for the atomic pulls even at this high temperature? And, now that I have already screwed thing up a bit, having run ABS and had problems, I am assuming that I should go in and clean with ABS (not PLA), is this accurate?

Appreciatively, - S

[neotko 1,417]

True the guide at http://support.3dverkstan.se/article/10-the says that. Personally Inuse what they call 'the lazy way or another method not described on the guide that consist on pushing in a ptfe of 3mm dia but that's overcomplicated for you atm'. I suppose that 250-260 must be why some people use Nylon filament for the atomic. Anyhow, just push some filament of the last one you used, heat to 220 - cooldown - atomic. I don't think that going too hot will help like you say if you might have some pla from before. ABS doesn't flows 'fast' at pla temps but indeed it will melt enough so it can be capture when cooling/pulling. You might just need to do it a few more times that the next time.

[Sukey 2]

 

@neotko I am very appreciative. This is a much more useful reference for the atomic method with info that applies more readily to my situation. Thank you! I'm off now to pull to see if that improves things.

[gr5 2,172]

I've seen some people recommend 260 for the heat phase of the atomic pull. I don't know why. For PLA 180c is plenty hot for that stage - the more important temperature is the low end temperature which varies depending on filament type and nozzle shape.

If you leave ABS at 260C for a while it will get extra sticky/gunky and it's harder to get it out. "a while" being like 10 minutes should be plenty of time but 1 minute should be safe. But if you print cooler than 250C it's hard to get strong layer adhesion unless you keep the fans off. To make things worse about 1 in 10 temp sensors is off by 10C (could be either way). So it's tricky to get the right printing temp.

There are many reasons not to switch a lot - the "leftover" in the bowden, feeder, and nozzle is only one of the reasons (some dust in the feeder can end up in the nozzle an hour after you switch). Another reason is that the higher temps of ABS make the white teflon isolator get softer and you won't care much with ABS but when you switch back to PLA the isolator is too soft and you can either get underextrusion or you can get clogs when the head cools down and some PLA flows into areas it shouldn't be and solidifies into a mushroom clog thing.

[gr5 2,172]

Another reason is it takes many hours and many prints to dial your printer in to get really good prints and as soon as you change materials all that effort doesn't apply to the new material. PLA is a bit easier to print so there's not as much to learn. To get good looking ABS prints you need a heated chamber.

[zoev89 73]

To my experience it is not only the hotend that needs cleaning when going from ABS to PLA. In my printer small ABS particles travel from the feeder into the bowden tube. So when I switch I atomic pull with PLA a couple of times until it pulls clean. Then I clean the feeder with a brush and the bowden tube. If small flakes get into your PLA it can cause a clogged nozzle at PLA print temperatures.

[cloakfiend 995]

When doing atomic pulls you may as well get an air duster (which usually comes with a straw) then pop that in the bowden tube and spray it to clear it, some people say they run the filament through pipe cleaners to rid it of dust as it enters the bowdentube, but this adds friction in my opinion so i just keep it clean after every print and print off the roll and that reduces the pull the feeder has to do hence no skipping and grinding. dust and fine particles of filament can build up over time and cause clogs too. i air dust everything, and its also great at taking large flat objects off the glass plate easily by holding it upside down and spraying it getting inbetween the glss and model. This basically releases the glue by supercooling it and the model just pops off as long as you get it inbetween the glass.

Edited September 7, 2015 by Guest