Material change not working (anymore)

[Desperate3D 0]

On our UM3+ Model, we have the problem that on material change the printer will immediately retract the material without waiting for the nozzle to heat up. As a consequence the material will not be ejected. 

When I do manually heat up the nozzle we can retract the material. 

Anybody has a hint what went wrong (or is damaged) ? 

I have already checked the temp. sensor in "Diagnose" and they seem to work.

Michael.

 

[Cazl120 0]

I have the same problem and it still prints but I don’t know how to heat the print core. How do you heat it?

[SandervG 1,521]

Hi @Desperate3D, thank you for your post and welcome to the community. 

I assume you mean you have an Ultimaker 3, or Ultimaker 3 Extended? We don't have an Ultimaker 3+ series.

 

Regarding your question, when your print finishes normally it automatically should retract your filament a tiny bit, so it should retract easily when you change filaments. Therefore it should not have to heat up when you change material. How do you mean the material won't be rejected? Can you describe what happens when you want to change filaments?

 

Thanks,

[Desperate3D 0]

Hello SandervG,

it is an UM3 Extended. 

I mean that the filament is not being pulled back (it sticks still somewhere in the Print-core). When I do heat up the Printcore (Menu->MATERIAL->PrintCore1->Temperatur) than I am able to pull it back and change the material (but this is a very annoying procedure) It worked in the beginning more reliable but now it is not woking at all.

I am using a new Printcore because the old one got completely destroyed by the attempt to print nylon.

Generally I think it is not a good idea not heating the print core before retracting the material.

Look at the picture what happens if you try to change material and repeat this procedure 2-3 times. (at least on my printer)

 

[gr5 2,225]

I've never changed the material with the menu - at least not in the last year.  I have one of these:

https://www.youmagine.com/designs/wedgebot-for-ultimaker2

 

I just pull out one filament and push in another.

 

Anyway - to your issue - when your print finishes - the printer is supposed to let the head cool to 180C and then it retracts the filament quite a bit - almost to the top of the "trumpet" of the print core.  That is probably where the failure is occurring.  Not on filament change.  I think you can abort that step if you are in a rush to get your print out at the end of a print.  Did you force the printer to skip that step?

 

Also what material were you using when this happened?  I noticed that the UM3 always seems to use 180C no matter what material is in there (so far that I've noticed).  So what material was this?

[SandervG 1,521]

Hi Desperate3D, 

 

thank you for the extra information. That indeed looks like some serious grinding. When you are not trying to change filament but with printing in general, how does it work for you then? 

Do you ever have any grinding then?

 

Have you ever had to change anything to the tension of the feeder? 

 

Probably not related, but I'm curious anyway; that your old print core got destroyed trying to print Nylon, do you think it is related to this (since you bring it up?) What happened to it?

[Desperate3D 0]

General printing in regard of the grinding issue is ok. So I think the pressure (tension) on the feeder seems to be ok, too.

Please see a picture of the "nylon" incident. That was really terrible and happened over night during the print of a large part. I think the printer should have some sort of sensors (e.g. the camera) to prevent this kind of problems. Anyway, I managed to remove the destroyed print core and had replaced them through new ones.

The print head still seems to be intact.

P.S At the moment I am using PLA.

[Desperate3D 0]

1 hour ago, gr5 said:

I've never changed the material with the menu - at least not in the last year.  I have one of these:

https://www.youmagine.com/designs/wedgebot-for-ultimaker2

 

I just pull out one filament and push in another.

 

Anyway - to your issue - when your print finishes - the printer is supposed to let the head cool to 180C and then it retracts the filament quite a bit - almost to the top of the "trumpet" of the print core.  That is probably where the failure is occurring.  Not on filament change.  I think you can abort that step if you are in a rush to get your print out at the end of a print.  Did you force the printer to skip that step?

 

Also what material were you using when this happened?  I noticed that the UM3 always seems to use 180C no matter what material is in there (so far that I've noticed).  So what material was this?

Thanks for the hint. I'll give the wedgebot a try.

I have never forced the printer to skip this step. And I am using PLA.

[Desperate3D 0]

I think I found the cause why the filament is not being pulled back. For whatever reason the end part of the filament was thickened (see picture) and it was not possible anymore to pull the filament through the transparent plastic hose. I removed the plastic hose along with the filament and pulled it the other way around out of the tube.

What can be the reason for the thickening ?

[SandervG 1,521]

Hi @Desperate3D , thank you for sharing your photo's. 

The accident with Nylon looks bad, but I don't think it is related to your experience with retracting material. Usually, such a blob forms when your 3D print got loose from the build plate and is being dragged along with your printhead. All of the sudden, your material can't go anywhere and a blob is formed. We took precautions in the design so the plastic should not be able to find its way up in the printhead if it would happen, but unfortunately these risks could not have been eliminated completely. 

Did you get help from your reseller while putting your printhead back in working condition again?

 

Re the thicker filament, my first suggestion would be to check if your front fan is still working. Just a thin string of filament could prevent your blades from spinning and cool air actively cooling. The result is that heat can travel up and make your filament soft. With the pressure it receives from the feeder, it can get thicker and be difficult to pull back through the bowden tube. 

 

Just to make sure, when you put your feeder back together, make sure this screw is in the housing, and not sticking out as it is in this photo.

 

[Desperate3D 0]

Hi Sander,

I think the problem is the front fan, it seems that it is not working reliable anymore (starts and stops and does not run smoothly) It seems that the fan was damaged by the nylon incident.

I will replace the fan and will see if the problem is solved (most likely yes).

The reseller could not help to solve the nylon issue. They said it was due to my negligence, I need to obey the print and stop it if something strange happens which could cause damage to the printer! But I think you will agree, that it is not feasible sitting 26 hours beneath your printer and watch everything is going well. I can very well live with the fact, that the print itself is not coming out well, but the printer should not destroy himself but stop working. Since the reseller (and Ultimaker) did not accept this as a warranty case (the printer is only 4 month old) I bought new print cores and a new print heat (just in case) myself.

But I have to admit: My confidence in Ultimaker suffered a lot (using an UM2 for quit some time successfully) and with the UM3 I had only bad luck (so far).

 

 

[SandervG 1,521]

Hi @Desperate3D , thank you for your response.

I'll send you a DM to discuss some more details, in general you should be able to receive the help you need. 

 

Let's hope the fan indeed will solve this for you. 

 

[Desperate3D 0]

thank you.