UM2+Olsson Block : still under-extrusion problems after replacing nozzle and PTFE coupler

[Netweaver 1]

Hi,

I have an Ultimaker 2, upgraded with Olsson block and an new fan shroud.

 

I'm having for quite some time moderate-to-heavy (but consistent) under-extrusion problems which I tried to fix using cold pulls, replacements of PTFE coupler, replacement of Nozzles but for the love of my life, I can't get it fixed. And recently it gotten worse, I'm getting 1 Extruder motor skip every so minute or so.

The prints are acceptable but not 'filled up', so there are consistent gaps in between the lines.

Outer surface quality and Z layer consistency is great.

 

Attached a few images, 1st 2 images are one of the terrible looking cold pull filament strands I produced recently.

The in-nozzle part is very clean, as it's a fresh nozzle but the part above it looks terrible, like there was something inside the head gnawing at it. Why? How?

 

I did do the E step calibration test, from the 100mm requested to be extruded, only 76mm was actually extruded.

 

Also, I did try to clean out the metal coupler/heat brake and the Olsson block but to no help. Anyone has an idea what the issue could be? Currently I have a Solex3d PTFE coupler in, I also had the I2K disc in and out, made no difference.

 

The worst case is to exchange the Metal coupler and the Olsson block itself also but that would be last resort.

 

Anyone having a clue?

 

Thanks.

Edited October 2, 2020 by Netweaver
typos

[Smithy 1,144]

Two more ideas:

• Is your middle fan at the back working?
• How old is your Bowden tube, do you feel any friction there?

[Smithy 1,144]

And one more 🙂

 

Your fan shroud looks very open, so there is a big chance that the cooling fans after the first layer, cools down the Olsson block too much. 

 

But you could check that when you print something without fans at all.

[Netweaver 1]

9 minutes ago, Smithy said:

Two more ideas:

• Is your middle fan at the back working?
• How old is your Bowden tube, do you feel any friction there?

You might have a point, I replaced also replaced the back fan by a smaller (way more quiet) Sunon fan. It is working properly though, I hear the fan spinning, I can stop the fan with my finger and I feel hot air blowing out towards the back of the printer. Is that the right direction? You think the heat is creeping up the filament causing the terrible part  of the cold pull plug?

 

Do you have an idea what the temperature of the metal head/frame should be with a properly working fan? With the Olsson block/nozzle at 205 degrees, I can keep touching the bottom horizontal (closest to the nozzle) part of the metal head frame (from the inside). It's warm, hot even but not unbearable at all.

I don't have a FLIR to make correct temp readings :)

 

The Bowden tube is still original, the friction at the motor end was a bit tight indeed due to a partly damaged tube. I just now replaced the tube with a new one (probably lower quality) which I had laying around for another project. The inner diameter is slightly bigger than the original UM one, so retractions probably will suffer a bit. At least another source of possible friction should be gone now.

 

The 1st layer I always do without fans on, 100% fan as of layer 2. I just printed the extrusion test 'shackles' with no fan.

I didn't hear any extruder motor skips.

 

one can see the outside layers not connected but in terms of dimensions, they fit nicely. Not too big, not too small. Unexpected but interesting ...

 

 

[Smithy 1,144]

1 minute ago, Netweaver said:

You might have a point, I replaced also replaced the back fan by a smaller (way more quiet) Sunon fan. It is working properly though, I hear the fan spinning, I can stop the fan with my finger and I feel hot air blowing out towards the back of the printer. Is that the right direction?

Thats the wrong direction, it is supposed to blow cold air from the back to front.

So before we try other things, turn the fan in the correct position and try to print again.

[Smithy 1,144]

5 minutes ago, Netweaver said:

Do you have an idea what the temperature of the metal head/frame should be with a properly working fan? With the Olsson block/nozzle at 205 degrees, I can keep touching the bottom horizontal (closest to the nozzle) part of the metal head frame (from the inside). It's warm, hot even but not unbearable at all.

I don't have a FLIR to make correct temp readings 🙂

 

Never tried to touch or measure the temp there, but turn first the fan....

 

6 minutes ago, Netweaver said:

one can see the outside layers not connected

 

Thats another story, I have it sometimes too, it is a question of speeds and when you equalise the speeds it gets much better.

[Netweaver 1]

fan direction flow changed, to the touch the metal is a bit cooler so that's a good sign already !

 

Next ? :)

[Smithy 1,144]

27 minutes ago, Netweaver said:

Next ? 🙂

Reprint 🙂 

[tinkergnome 927]

The PTFE coupler looks funny.... or wrong... or... at least quite different to those that i know? Is this a DIY solution or has the shape changed nowadays? Where does the bowden tube ends?

 

 

 

It should look like this, as far as i remember....?

https://fbrc8.com/collections/ultimaker-2-spare-parts/products/tfm-isolator-coupler-um2-um2-go-ext-plus

 

[Netweaver 1]

1 minute ago, tinkergnome said:

The PTFE coupler looks funny.... or wrong... or... at least quite different to those that i know? Is this a DIY solution or has the shape changed nowadays? Where does the bowden tube ends?

 

 

 

It should look like this, as far as i remember....?

https://fbrc8.com/collections/ultimaker-2-spare-parts/products/tfm-isolator-coupler-um2-um2-go-ext-plus

 

 

This is the 3DSolex version : https://3dsolex.com/product/tf2k/

Now using it without the I2K coupler to reduced the number of variables while troubleshooting. But if I get the normal PLA prints back 100% ok, then I'll put that I2K ring back in, to go allow higher temps without squeezing my coupler.

 

It was discussend (amongst other places) here : 

Btw, great firmware you made, using it with pleasure on mu UM2 for years already !

[Netweaver 1]

31 minutes ago, Smithy said:

Reprint 🙂 

Just did, maybe slightly better top layer, still very clearly walls separated. This was sliced in draft mode, 4 walls and Equalize filament flow on:

[Smithy 1,144]

Don't use the draft mode, if you don't want a "draft" as result 🙂

 

Use the normal profile and important equalise all the speeds. Set Outer wall , inner wall, and so on to 40mm and try it again. The separation you see is a result of different speeds and printing too fast. 

[tinkergnome 927]

7 minutes ago, Netweaver said:

This is the 3DSolex version

 

Ok, but... it still looks very different...? This can't be the part from your link - even if there is a huge camera distortion....?

I never saw a conical coupler... this can't be correct. 🤷‍♂️

 

 

Besides of the spring (instead of a spacer) it should look like this:

https://fbrc8.zendesk.com/hc/en-us/articles/115004703983-Printhead-Diagram-Ultimaker-2-

 

 

 

 

[Netweaver 1]

4 minutes ago, tinkergnome said:

 

Ok, but... it still looks very different...? This can't be the part from your link - even if there is a huge camera distortion....?

I never saw a conical coupler... this can't be correct. 🤷‍♂️

 

 

Besides of the spring (instead of a spacer) it should look like this:

https://fbrc8.zendesk.com/hc/en-us/articles/115004703983-Printhead-Diagram-Ultimaker-2-

 

 

 

 

 

It is, I even have 2 of them. Identical. Carl (3DSOLEX owner) sent me one extra. And on the arty drawing on the left (from the website) you can see (somehow) it's not straight down, there is a 'gap'on each side at the top.

[Netweaver 1]

5 hours ago, Smithy said:

Don't use the draft mode, if you don't want a "draft" as result 🙂

 

Use the normal profile and important equalise all the speeds. Set Outer wall , inner wall, and so on to 40mm and try it again. The separation you see is a result of different speeds and printing too fast. 

 

All fine now. So I guess the original problem was the extra friction of the slightly damaged Bowden tube + the extra friction of the too hot/mushy filament above the metal coupler/heatbrake due to the insufficient airflow, due to the wrong direction of the hot end fan. Phew ...

 

And for the rest, I'll try with my Race nozzle to see if I can get better results at higher speeds. It might be the Olsson block can only melt so much plastic/s, that higher speeds are not feasible with good quality.

Maybe the Race block is also needed for that. And a better feeder, as I'm not very happy with the feeder in general. 

And I'll get the I2K chip back in and see if I can get some play with some real higher temp materials.

 

Thanks for all the support and thinking along, I was not suspecting the bowden tube at all. 

 

A day one hasn't learned anything, is a wasted day  :)

Edited October 2, 2020 by Netweaver
typos

[Smithy 1,144]

I am glad I could help. 😎