Underextrusion

[shnick 0]

Hello,

I have an Ultimaker 2 which for the past 2 months I cannot get it to print anything from to bottom without a single underextrusion.

First I would like to ask if, after atomic method performed once or twice, is it normal that during changing the filament procedure at the part where the new filament has to be inserted the feeding system to go back and forth once it gets near the tip of the extruder.

Then I start printing and depending on the size of the object the printer underextrudes aprox. once or twice per each layer.

I check the feeder system and it appears to work just fine. Here I have to add that position of the hex screw on top of the feeding system is set to the first indicating line from top to bottom.

Then the bowden tube seems to be OK. Maybe some small particles of dust on the inside but I don't think that this could block the extruder.

Next the extruder on which I performed as I mentioned earlier that I tried to clean several times with the atomic method after which it seemed to be clean.

In the past I used some poor quality filament which was not good at all, but now I'm using Faberdashery of whom I heard only good feedback.

I tried different printing parameters with temperatures from 200 to 235 degrees and speeds around 50mm/s, layers around 0.15mm.

On the same printer a few month ago I was printing pretty well with 80-100mm/s and a temperature of 215 degrees with Innofill filament.

I have the printer for almost a year, but I printed only 180hrs.

Please let me now if anyone has some ideas on this because I'm out of them.

 

[kris 29]

Hi Shnick,

I use two UM2's, one purely for PLA and one for ABS. Both PLA and ABS from Innofil.

For PLA: Going any higher then 50mm/s and 0.1mm layer thickness will always cause underextrusion for me as well. I usually stick below these values. If the dimensions are not critical I even raise the temperature to 240°C.

ABS is a totally different story: 75mm/s and 0.25mm layer thickness are no problem at all, I even lower the temperature from 260°C to 240°C usually without any signs of underextrusion for >20h prints.

Seems to me that at least the Innofil PLA is a lot harder to extrude. I'll change to colorfabb hoping it will get better.

Cheers,

Kris

 

[personal-drones 44]

Hello Shnick, what apparently worked for me in a similar situation of chronic underextrusion on the UM2, getting worse and worse over time, was to change the teflon spacer, see http://umforum.ultimaker.com/index.php?/topic/9320-is-this-teflon-coupler-gone/

Not sure this will apply to your problem, but it might be worth a try.

Up to now I was never able to get a decent print with PLA if the layer height was over 0.1, because of underextrusion. 0.1 and speeds around 30-50 work well for me right now. The slower, the better quality.

 

[tinydancer 0]

Depending on the hours you have on them, the teflon spacer is likely the culprit. Especially if you're printing PLA constantly at 240. Personally I have yet to go above 210 except when I did the extrusion test at 230. Take the spacer out and see what it looks like.

 

[shnick 0]

Hi Shnick,

I use two UM2's, one purely for PLA and one for ABS. Both PLA and ABS from Innofil.

For PLA: Going any higher then 50mm/s and 0.1mm layer thickness will always cause underextrusion for me as well. I usually stick below these values. If the dimensions are not critical I even raise the temperature to 240°C.

ABS is a totally different story: 75mm/s and 0.25mm layer thickness are no problem at all, I even lower the temperature from 260°C to 240°C usually without any signs of underextrusion for >20h prints.

Seems to me that at least the Innofil PLA is a lot harder to extrude. I'll change to colorfabb hoping it will get better.

Cheers,

Kris

 

Kris I printed white Innofil with 210 temperature and it printed just nice. When I started to experience underextrusion on and on I tried to increase the temperature to see if this helps because I also changed the filament provider. Now, as I sad, I bought some filament from Faberdashery which has an amazing colour it feels pretty nice when printed.

Unfortunately, I couldn't complete any print perfectly by now.

 

[shnick 0]

Hello Shnick, what apparently worked for me in a similar situation of chronic underextrusion on the UM2, getting worse and worse over time, was to change the teflon spacer, see http://umforum.ultimaker.com/index.php?/topic/9320-is-this-teflon-coupler-gone/

Not sure this will apply to your problem, but it might be worth a try.

Up to now I was never able to get a decent print with PLA if the layer height was over 0.1, because of underextrusion. 0.1 and speeds around 30-50 work well for me right now. The slower, the better quality.

 

Thanks very much for your advice. It's a good idea as I didn't think by now to inspect this piece.

I will check it tomorrow and let you know.

 

[shnick 0]

Depending on the hours you have on them, the teflon spacer is likely the culprit. Especially if you're printing PLA constantly at 240. Personally I have yet to go above 210 except when I did the extrusion test at 230. Take the spacer out and see what it looks like.

 

Well I never printed the PLA at 240 by now. I tried as much as 235 to be honest. But I will definately check the teflon spacer.

 

[personal-drones 44]

Thanks for posting a follow up, definitely interested in your investigation.

> I will check it tomorrow and let you know.

 

[shnick 0]

Hello guys,

So I disassembled the extruder and took out the teflon spacer which seems to have experienced some deformation where it touches the hot end isolator.

Now, can someone confirm that the filament should pass through the teflon spacer without any obstruction or friction? Because I tried to put in a piece of filament to see if it comes out on the other side and it doesn't.

I tried to make some pictures but I don't have a professional camera in hand so I made them with my phone hope it helps to tell me something.

https://drive.google.com/file/d/0B-hqmWaCQjV9bjZOeFlQa1llYUE/view?usp=sharing

https://drive.google.com/file/d/0B-hqmWaCQjV9OVdEQTdMbHIzNTQ/view?usp=sharing

 

[shnick 0]

I decided to take the problem into my both hands and restored the inner diameter of the teflon spacer with the help of a power drill. After that I checked if the filament passes through the object and it went nice and smooth.

I reassembled the parts (here I had some problems because the spacing between parts was a little bit different before, but I double checked everything. Then I calibrated the bed inserted some material and started to print something small to see how it goes. Surprise surprise everything went very good. The problem is solved hopefully for a long time from now.

I still have a question though, anyone knows what kind of material is the teflon spacer made of? I am thinking to remake this part out of a textolite to see if it works better and doesn't change its shape due temperature.

To conclude, thank you all for your advice and especially to Personal Drones.

 

[personal-drones 44]

Shnick very glad we nailed it down so quickly.

Also good to hear drilling worked, thank you for the update.

I decided to take the problem into my both hands and restored the inner diameter of the teflon spacer with the help of a power drill. After that I checked if the filament passes through the object and it went nice and smooth.

I reassembled the parts (here I had some problems because the spacing between parts was a little bit different before, but I double checked everything. Then I calibrated the bed inserted some material and started to print something small to see how it goes. Surprise surprise everything went very good. The problem is solved hopefully for a long time from now.

I still have a question though, anyone knows what kind of material is the teflon spacer made of? I am thinking to remake this part out of a textolite to see if it works better and doesn't change its shape due temperature.

To conclude, thank you all for your advice and especially to Personal Drones.

[vany-chaotic 0]

I still have a question though, anyone knows what kind of material is the teflon spacer made of? I am thinking to remake this part out of a textolite to see if it works better and doesn't change its shape due temperature.

To conclude, thank you all for your advice and especially to Personal Drones.

 

Well, if I am not too mistaken I guess the teflon spacer is made out of teflon

[Polytetrafluoroethylene - known for its awesome heat resistance]

 

[shnick 0]

Well, if I am not too mistaken I guess the teflon spacer is made out of teflon

[Polytetrafluoroethylene - known for its awesome heat resistance]

 

:smile: Good to know. I was thinking trying to rebuild this part from a textolite. Any thoughts about this?

 

[DidierKlein 729]

If it's a new UM2 it's PTFE with 25% glassfill, if it's an older UM2 then it's only PTFE

There's an interesting discussion on the forum for alternatives:

http://umforum.ultimaker.com/index.php?/topic/7024-teflon-spacer-replacement/

This particular part of the printer is being tested in other materials too from what i know

 

[gr5 2,172]

Be careful what material you choose. You want something that is low friction for both solid PLA, solid ABS, solid Nylon and also doesn't stick too much to melted PLA, melted ABS and melted Nylon. PTFE is very good at this. Other materials (e.g. steel) not so good.

Also the material needs to not melt at temps up to about 280C (in fact this is the key part that limits head temperature.

Some people have put a very thin disk of polyimide or other materials (about 1mm thick) between the isolator and the heater block and have had very good luck printing this way. The PTFE stays more than 50C cooler than the heater block.

 

[shnick 0]

I'll make some research on materials properties and will let you guys know if I find something worthy enough to try replacing the PTFE.

Also, a question came to my mind just now. Does anyone know if this part can be replaced on warranty by Ultimaker?