Auch... No dual extruders anymore?

[3dcase 37]

Looks like most dual extruders are dismantled?

Not much happening here..

I'm still watching it print.

Anyone wondered...

Would it be better and cleaner if the printhead only did one layer at the time.

Now it prints two layers per extruder.

At 0.12 perlayer thats. 0.24mm difference. So the shoulder of the nozzle (the area without the hole) moves the other extruded material away?

Before printing you've levelled the nozzle's with a piece of paper say, 0.1mm?

The way I see now is: as long as you print 0.05 layers you'r fine. thicker layers would give a mess?

I might be wrong.....

More opinions welcome...

 

[Dim3nsioneer 557]

I guess everybody was waiting for Daid to include the dual extruder stuff... :wink: I plan to try it next week...

 

...

Would it be better and cleaner if the printhead only did one layer at the time.

Now it prints two layers per extruder.

At 0.12 perlayer thats. 0.24mm difference. So the shoulder of the nozzle (the area without the hole) moves the other extruded material away?

Before printing you've levelled the nozzle's with a piece of paper say, 0.1mm?

The way I see now is: as long as you print 0.05 layers you'r fine. thicker layers would give a mess?

...

 

These are some very good questions / remarks, I think.

I cannot completely follow you with the two layers. As far as I see it, Cura (I refer to version 13.10 here as I did no dual extrusion so far with 13.11 or 13.11.2) starts with an extruder at one layer (let's call it no. 1) and goes with this extruder onto the next layer (no. 2). It then switches to the other extruder on layer 2 and continues until layer 3 where it switches back to the first extruder and finishes the layer 3 and goes onto layer 4 and so on... Thus, it should only see 0.12mm difference, never 0.24mm... right?

Assuming the two hotends to be positioned on the same height (which is indeed VERY tricky with the current setup, but not completely impossible), the unused hotend should have the same height as the used one and might slightly touch the printed material of the active hotend (by some microns), but it shouldn't move the material away, should it?

You're absolutely right with the leveling. It is ABSOLUTELY CRUCIAL for dual extrusion up to a level of not only 0.1mm but far more accurate. I bought myself some very thin feelers (down to 0.03mm). They give you much more information than the sheet of paper (which is absolutely ok for single extrusion, I think).

I still have the acrylic standard bed... which is a BANANA...! It's nearly impossible to get a reasonable dual extrusion leveling with this bed. People with a glass bed are far better off; they really have a chance. However, the bed is not the only influence onto the leveling quality.

What about the 6mm rails the print head runs along? Are they straight? Up to what deviation?

What about the 8mm rods the rails of the print head are mounted to?

A linear deviation is no problem as it cancels out at the end, but quadratic, cubic and so on influences do not... :sad:

This is just theoretical. As mentioned at the beginning, I plan some test next week or the week after.

 

[3dcase 37]

I cannot completely follow you with the two layers.

 

I do not know if I am wright, tried to write it as question, because it's tricky.

Let's say you print 2 towers. layers 0.1mm

With single extruder; left layer 1, right layer 1, Right layer 2, left layer 2, left layer3 etc. etc etc.

Normally, but for sure in this case, the (Theoretical) clearance is always the paper and layer thickness I started with.

But now I make 2 towers extra, 4 in a row..

The movements at least in 13.11 are the same as for 1 extruder.

So color 1 from left to right. Z down. layer 2 from right to left.

Next comes colour 2, that has to drop 2 layers down? As far as I can see it.

And for sure hits a little bit the other colour?

As I said before, I give it another try tomorrow to be sure, might be wrong.

But for now I think the clearance is 2 layerthickness(es) or none.

It would be more precise if it printed one layer at a time, so finish one layer before stating another one.

 

[Daid 306]

I think you are wrong, the material is printed A,B B,A as you see, but like this:

Layer 1, color A

Layer 1, color B

Layer 2, color B

Layer 2, color A

Layer 3, color A

Layer 3, color B

Layer 4, color B

Layer 4, color A

So every color as a layer beneath it of the proper color. There is no gap of a layer in between.

 

13.11.2 also adds this "round robin" extruder changes to dual-extrusion support material. As well as adding the experimental wipe&prime tower as the ooze-shield.

It also adds retraction when printing the support material, so that also helps.

The wipe&prime tower still needs some tuning I think.

 

[3dcase 37]

I think you are wrong, the material is printed A,B B,A as you see, but like this:

 

You right, me wrong, daid.!

Watched it print again, and indeed no extra gaps.

Not sure about Round Robin, I'll try that one out when my dual support is up and running.

My tilburgse Google came up with obesitas birds?

But I guess you refer to the Algorithm or sequence scheduling...

Ooze shield checked, and approved!

Ooze shield works cleaner then the tower i guess, wipes from every direction.

 

[Daid 306]

The advantage of the wipe tower is that it also primes the extruder, so that helps in if one of the extruders leaked a lot. I actually managed to make quite good prints at 220C with both the ooze-shield and wipe tower enabled.

 

[Dim3nsioneer 557]

Hey Daid

I'm very sorry but I think I found a bug in the dual extrusion of Cura. To me it looks as if Cura takes the filament diameter no. 1 for both filaments even when filament diameter 2 is filled in with a non-zero value.

I just tried to do some dual extrusion print with filament 1 being 2.9mm in diameter and filament 2 being 2.8mm in diameter... and I got a mess for material 2 (too much material, which I never got when printing this material alone).

I then checked some lines of the gcode and .... yes, as I said, I'm sorry... it seems to go back even to Cura 13.06.4 (first Cura version I used).

Please let me know if there is a work-around....

 

[3dcase 37]

The advantage of the wipe tower is that it also primes the extruder, so that helps in if one of the extruders leaked a lot. I actually managed to make quite good prints at 220C with both the ooze-shield and wipe tower enabled.

 

Used Primetower and ooze shield together, looked good!

Pretty clean on the bed.

Even better after just breaking away the ooze shield, no further cleaning done.

 

[Dim3nsioneer 557]

I would like to see some dual extruder prints where the idle extruder has to cross already printed material. I'm currently trying this: https://www.youmagine.com/designs/target-dual-extrusion-test. I usually scale it down to half its size. Although the ooze shield certainly helps, I still get a mess... The problem is the idle extruder oozing while over the print (no ooze shield of the world can help with this...).

I'm especially surprised to read about printing at 220°C. I'm currently working at 194°C and the oozing is still awful. Daid, did you do your 220°C-prints with Ultimaker PLA? At which speed?

 

[Daid 306]

I would like to see some dual extruder prints where the idle extruder has to cross already printed material. I'm currently trying this: https://www.youmagine.com/designs/target-dual-extrusion-test. I usually scale it down to half its size. Although the ooze shield certainly helps, I still get a mess... The problem is the idle extruder oozing while over the print (no ooze shield of the world can help with this...).

I'm especially surprised to read about printing at 220°C. I'm currently working at 194°C and the oozing is still awful. Daid, did you do your 220°C-prints with Ultimaker PLA? At which speed?

 

I used Ultimaker silver, Ultimaker red and Ultimaker blue. It does ooze a bit. But, the UM2 hotend oozes less then the UM-Original hotend, so that helped for me.

(But, the UM2 hotend in dual-extrusion still has some cooling issues right now. So it jams quite easy)

 

[Dim3nsioneer 557]

I used Ultimaker silver, Ultimaker red and Ultimaker blue. It does ooze a bit. But, the UM2 hotend oozes less then the UM-Original hotend, so that helped for me.

(But, the UM2 hotend in dual-extrusion still has some cooling issues right now. So it jams quite easy)

 

I don't know what you're talking about... there is no UM2 dual extruder... :wink:

Is the Ultimaker PLA pure PLA or also PLA/PHA mixture as the Colorfabb stuff?

Could you say something about the speed?

 

[Dim3nsioneer 557]

As promised here some feedback on the Dual Extruder Aids in Cura 13.11.2.

My goal was to achieve a dual extrusion print without any traces of the 'wrong' color if the idle extruder has to cross both materials while the active extruder printing. I built myself a test design (https://www.youmagine.com/designs/target-dual-extrusion-test) which I scaled down to half in x and y and for testing to 0.5mm thickness.

The prints were made with PLA at 25 mm/s.

The present result is this:

I also made a 4mm thick version of it:

The results are not perfect but somehow ok. I've intentionally chosen two colors with large contrast in order to see spills.

And this is what I learned and a few questions that rose up:

- First things first: Both, Wipe tower and Ooze shield, did their job quite well (it's great to have both of these options, thx Daid, please keep them!)

- As printing on Kapton tape, adhesion was an issue at the chosen temperature of 190°C. The ooze shield being a single line had not the slightest chance of sticking to the Kapton tape. Therefore I had to use a brim. Unfortunately the Brim does not include the Wipe tower which led to its delamination in the thick version as visible on the lower picture.

On my wishlist for the next Cura version: please let the brim include the Wipe tower in the brim (nice to have: a connections between the two brims if not large enough to connect anyway... but no need-to-have)

- I printed with combing disabled as with it enabled the print head just prints over the 'wrong' color leaving a very strong line. The blue lines visible in both pictures on the white area originate from G0-movements while the filament was retracted. It's simple oozing. This effect is especially strong on layers where the blue is the second color to printed (as the gap to the already printed white surface is (theoretically) zero there). However, I'm pretty sure I can tweak the GCODE to get rid of this.

- I had the impression, that on each layer two lines were printed for the ooze shield on top of each other; one for each material. This led to an increased pressure inside the hotend of the second material and some subsequent splotching. Something seems not ideal there. It's the same thing with the ooze shield line of the second material on the brim (layer zero).

- I already reported the filament diamenter bug in Cura in a post above. A bugfix for this is also on my wishlist for the next Cura version.

 

...

The wipe&prime tower still needs some tuning I think.

 

My conclusion:

The Dual Extruder on the Original Ultimaker has already come very close to the point where it is not anymore 'experimental' with some tweaking...

 

[LePaul 322]

Great to see some progress with this

 

[3dcase 37]

Hi Daid,

Will addressing it help?

because Ooze shields where discussed in this topic, I dump it here.

 

Strange effect in the ooze shield, it starts halfway on the inside as well.

Have n't printed it yet, might attach to the insidewall, but it looks strange....

 

[Dim3nsioneer 557]

Quick update to post no. http://umforum.ultimaker.com/index.php?/topic/3511-auch-no-dual-extruders-anymore/&do=findComment&comment=27453: Finally, I got rid of the last few 'transfer lines'. A quite delicate tuning of the flow is necessary in order to prevent first signs of overextrusion (it gets messy then immediately) and clear evidence of underextrusion.

 

[Daid 306]

I've put up a quick test build at http://software.ultimaker.com/Cura_closed_beta/

It contains a few fixes related to retraction and the wipe tower, so it might be of interest.

 

[Dim3nsioneer 557]

Hi Daid

Thanks for the test version. I just had a look into it and this is what I have (not) found:

- Retract seems to work properly now with combing (great!).

- What happens if (for a large dual extruder print) the wipe&prime tower is placed beyond the border of the print area? I had the impression (maybe I'm wrong) that the w&p tower is not included in the 'outside of print area'-check.

- What is the idea behind definining the size of the wipe&prime tower as a volume and not as a surface (mm2) or even a line length (mm)? I found it hard to get the right size. For priming the the extruder, the surface (actually the corresponding line length) is the important parameter...b.t.w.: the surface stays the same for a given volume independent of the height of the print...so, isn't it actually the area which is set (wrong labeling?)?

- The brim around wipe&prime tower is still missing

- Filament diameter2 is not yet implemented

I hope this helps for finishing Cura 13.12...

 

[Daid 306]

The wipe tower size is done in volume, as you want to extrude a certain amount of volume to get the extrusion going. If you put in thinner layers the wipe tower needs to be bigger to extrude the same amount of material. This setting does this without needing to adjust the setting.

Note, this is the volume of material per layer, so 15mm^3 volume on 0.1mm layers results in a square_root( 15mm^3 / 0.1 ) ~= 12.25mm, 12.25mm x 12.25mm wipe tower.

The wipe tower is indeed not yet calculated in the print area yet, I still need to fix this.

 

[Dim3nsioneer 557]

OK, now I understand. It's the volume per layer... then it's clear it's independent of height... well, I may have understood in the first time if a had a second coffee... thx for the explanation!