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braddock

Ultimaker blue PLA, not great?

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I'm calling this print successful, simply because it finished, unlike any of my prints in the past few days.

This print didn't exhibit any under extruding signs such as the feeder skipping, all the base layers were nice and smooth, and the impressions from the gear wheel on the filament suggest to me the tension is fine.

However, almost all the way through, you can see the surface quality is slightly porous. I'm going to change back to the orange PLA I have on my next print, but does anyone else have issues with the ultimaker blue PLA?

blue Pla 02

blue Pla 01

 

 

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Hmnn, I know (guess) that this will vary between material manufacturers/brands but your temperatures just seem too high to me. Most of the PLA specs I have seen from various people set the upper limit at 220 degrees.

I use Faberdashery and Colourfabb products and at speeds up to 80m/s have not needed to go above 210 degrees. At 60m/s Colourfabb seems quite happy at 205 degrees (they test on Ultimakers) although I accept theirs is not pure PLA, being mixed with PHA.

I do wonder if you are masking some other problem with extrusion by using such high temperatures?

 

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I agree it shouldn't be that high, when I first got my U2 I was able to print at 190 using the orange PLA, I really don't know what's going on.

 

 

Hmnn, I know (guess) that this will vary between material manufacturers/brands but your temperatures just seem too high to me. Most of the PLA specs I have seen from various people set the upper limit at 220 degrees.

I use Faberdashery and Colourfabb products and at speeds up to 80m/s have not needed to go above 210 degrees. At 60m/s Colourfabb seems quite happy at 205 degrees (they test on Ultimakers) although I accept theirs is not pure PLA, being mixed with PHA.

I do wonder if you are masking some other problem with extrusion by using such high temperatures?

 

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Ulti-blue requires a slightly higher temperature then most of the other colors, however not 245°C high.

Have you tried different materials beside the blue?

If you release the bowden tube from the feeder mechanism, how does the PLA slide through the bowden tube?

When your hot end is hot, and your bowden tube is still free from the feeder, can you manually create a constant flow?

Can you upload a picture of your filament, what does it look like after it went through your feeding mechanism?

Thanks! :)

 

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I suspect that either:

1) Your feeder isn't as strong as it should be or

2) You have a partial clog in the head (maybe some old PLA has turned to gunk on the inner wall of the nozzle).

I forget - have you played with extruder spring tension lately?

Also all you guys who talk about temperature and speed keep leaving out layer height. There's a huge difference between 50mm/sec at 220C with .2mm layer height versus .1mm layer height. In fact it's a 2X difference.

But I agree that this sounds like the UM2 should be able to do a little better.

 

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When you say the feeder isn't as strong as it should be, do you mean it may be defective? I have played with the tension quite a bit, it's back up to where it was originally now, just slightly tighter. It leaves fairly prominent teeth marks in the material, but it's a fine line between this, and grinding the material flat during many retractions.

I've cleaned the nozzle 100 times in the past few weeks as best I can. How do you actually pull the nozzle apart though?

Thanks, it'll end up faux bronze.

 

 

I suspect that either:

1) Your feeder isn't as strong as it should be or

2) You have a partial clog in the head (maybe some old PLA has turned to gunk on the inner wall of the nozzle).

I forget - have you played with extruder spring tension lately?

Also all you guys who talk about temperature and speed keep leaving out layer height. There's a huge difference between 50mm/sec at 220C with .2mm layer height versus .1mm layer height. In fact it's a 2X difference.

But I agree that this sounds like the UM2 should be able to do a little better.

 

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Well I'm not certain you've got a thin layer of gunk inside your nozzle but that seems most likely. If it were me I would just print at a slow speed but if you really want to see if cleaning out the nozzle helps...

 

How do you actually pull the nozzle apart though?

 

Very carefully. See? I'm so helpful :)

I haven't done it yet. The nozzle is integrated with the heat chamber so you'll also have to remove the heater and thermocouple. Better to do it now before the whole thing is fused I suppose.

Read post #18 and look at picture:

http://umforum.ultimaker.com/index.php?/topic/3037-ultimaker-2-printing-issue/?p=22333

And post #8 has a very important note:

http://umforum.ultimaker.com/index.php?/topic/3971-more-clogging-issues/?p=31744

More notes:

http://umforum.ultimaker.com/index.php?/topic/3749-clogged-um2/?p=30178

 

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By the way - please explain how I would grind the filament to dust if I *wanted* to do this (more that I want to avoid!). Do I make it tighter or looser to make it grind more? Right now it is as it came from factory which is *almost* all the way loose (white square tension indicator at the top).

 

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I think for me it happens if I have too much tension, and a print with many retractions. Slowing down the retraction speed and distance seems to help.

I'm sure there's other factors, but it doesn't seem to affect everyone?

 

By the way - please explain how I would grind the filament to dust if I *wanted* to do this (more that I want to avoid!). Do I make it tighter or looser to make it grind more? Right now it is as it came from factory which is *almost* all the way loose (white square tension indicator at the top).

 

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I followed what someone else posted, and pulled out the bowden tube, heated the nozzle to 220, manually inserted a stick of PLA, mushed it down and pushed out all the gunk I could, let it cool to 90 degrees, then pulled it out. I was surprised to see some blue goo, considering i've just done 6 hours of printing with orange, so I'm pretty confident its clear now. Also, when I pulled it out, the little nub of PLA that was poking out the end of the nozzle came with it, so it's gotta be clear.

 

Well I'm not certain you've got a thin layer of gunk inside your nozzle but that seems most likely. If it were me I would just print at a slow speed but if you really want to see if cleaning out the nozzle helps...

Very carefully. See? I'm so helpful :)

I haven't done it yet. The nozzle is integrated with the heat chamber so you'll also have to remove the heater and thermocouple. Better to do it now before the whole thing is fused I suppose.

Read post #18 and look at picture:

http://umforum.ultimaker.com/index.php?/topic/3037-ultimaker-2-printing-issue/?p=22333

And post #8 has a very important note:

http://umforum.ultimaker.com/index.php?/topic/3971-more-clogging-issues/?p=31744

More notes:

http://umforum.ultimaker.com/index.php?/topic/3749-clogged-um2/?p=30178

 

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What is the maximum retraction speed you have tried so far? And what is the speed you use now?

 

I think by default, its 25mm/s so I just turned it down to 18. I know some guys are running 35 though.

Also changed the distance from 4.5mm to 3.00mm though I'm not sure how much difference that makes.

 

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By the way - please explain how I would grind the filament to dust if I *wanted* to do this (more that I want to avoid!). Do I make it tighter or looser to make it grind more? Right now it is as it came from factory which is *almost* all the way loose (white square tension indicator at the top).

 

Hi gr5!

The only way I've found to "grind" the filament is to apply too much pressure at the extruder stepper. If you adjust the screw such that the tension indicator moves down, you're effectively increasing the spring rate on the arm of the roller bearing, thus applying a greater normal force on the filament. If I tighten the screw all the way (the indicator is at the bottom), the knurl on the filament is pressed so deep that it's forming small pyramids of plastic that fairly easily separate from the filament itself when the extruder begins to rotate. More rotation = more pyramids = grinding.

That being said, I leave my tension at the minimum, and don't have any skipping between the knurl and the filament. My extruder stepper will miss steps far before the knurl and the filament skip (and is does so frequently unless I'm running at 235C-245C for 0.2mm layers at 50 mm/s).

 

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The issue of filament grinding in general is a big issue on the UM1, for sure - more than on the UM2. However, it's hard to adjust the spring on the UM1 to be too tight, as I think there's a hard stop on it before it gets to that point.

The spring on the back of the feeder should be about 11-12mm long when the filament is loaded. The main things to check for on the UM1 are:

1) that the filament is loaded and locked properly (with the lever all the way at the bottom of the slot)

2) that the delrin pressure wheel can rotate freely and isn't deformed

3) that the drive bolt is properly positioned so that the most pronounced teeth are the ones engaging the filament.

 

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Yes, retraction speed is only set on the machine on a UM2 - at least if you are using Cura and its ultigcode setting. If you use a different slicer, or put Cura into UM1/Reprap mode, then you can - indeed have to - specify the distance in the slicer. But that's less flexible at print time, so I don't recommend it.

 

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Clearly there's some work to be done to define the parameters for the extruder - it seems like maybe the tension range for the extruder is not optimal. From most of what of heard, it seems like the lowest setting for the extruder tension is the best one - anything higher seems likely to cause stripping, and trying anything lower can result in the tensioner stopping working. So it's adjustable, but the useful range of the adjustment seems to be pretty low.

Retraction should not need to cause filament damage at all. I think I was one of the first to propose faster and longer retractions: I use 5.5mm/s at 35mm/s. And I've done prints which retracted on average more than once a second, non-stop for almost 48 hours - and without the slightest damage to the filament. So something else is going on which might be exacerbated by retractions; but that's not the primary cause.

 

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Yes, definitely... I have the spool on the floor a couple of feet below, and three feet or so behind the printer, on a turntable, so that there is several meters of loosely coiled filament hanging in space that the printer can easily feed on. Generally speaking the gradual tug on the filament will rotate the spool and unwind more, but I can check on it every few hours just to make sure there is still plenty of loose filament, and undo any tangles that do happen before they impact the printer.

 

I think the location of the spool, and tension of the material, and the force required to pull it along also causes issues for the feeder. I read that you place yours on the floor?

 

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