help! my UM3 has material fill up on its head

[fzqxfzqx 0]

Hi Forum user. 

 

I have an ultimaker 3 that for an unknown reason the Z axis doesn't seem to be moving down as it prints, it has caused the material PLA and PVA build up on the print head compartment and damaged the bed significantly. before I start the print I always do active levelling and the first few layer is fine, it only happens when I walk away and let it run.

 

Does anyone has the similar problem or know what I have done wrong? I have attached the image of the printer and the cura project file and g code I used for printing. Really appreciate anyone can shine some light on this. as this has happened to me twice now after some costly replacement of the print heads. 

 

 

 

 

cover_1.3mf

cover_1.gcode

[Nicolinux 288]

I'll print your .gcode on my UM3 and see what happens.

[fzqxfzqx 0]

Thank you NIcolinux, please do let me know.

[gr5 2,192]

I never heard of this.  This is new.

 

I looked at your gcode file and the Z should be moving - it goes to 11mm - your part should be about 11mm tall, right? 

 

So this is strange that the Z axis works fine when you home it but when you go to print it doesn't move?  That doesn't seem likely.  Maybe the homing is way off such that it is squishing hard into the plate and even after moving the bed down 3mm the nozzle is still touching the glass.  That I could believe.

[fzqxfzqx 0]

Hi gr5, 

 

yes that is correct. the model is about 11mm thick, 

 

In regards to the z-axis, I have turned on the active levelling for UM3 for each print and I watched it print ok for the first few layer before I left it to do its job. so I believe the bed levelling was correct at the start of the print. 

 

 

[gr5 2,192]

Then I suspect nothing is wrong with z.  What happened is your part came loose after a while and was carried around on the bed for hours while the filament slowly squished back into the head.

 

The trick is to learn to get your parts to stick better.  I have a video about this buy am traveling today and can't help you.

[CatG 0]

This also happened to our Ultimaker 3 within a few months of getting it - it was so bad that we had to completely replace the machine. The first time, one of the screws on the base of the glass plate had also popped completely off (it looks from your pictures that the screw on the left is also close to coming off - this may make it appear as though the Z axis hasn't moved when in fact the glass plate is just pushed up)

 

gr5 is right, it was an issue with the part coming loose from the bed, then being left to print. I always use glue with our UM3 and make sure that large prints are started in the morning so that if I am leaving them overnight I would notice any major problems before I left it alone. 

 

I don't bother with active levelling before each print but this may just be because I am used to manually levelling all of our machines, tweaking by hand as they start printing to make sure they are getting good adhesion.

[geert_2 558]

That white plastic cover in front of the nozzles, is it needed for technical reasons? Or is it just for aesthetics? Because, if it would not be needed and if it would be left out, any build-up of molten filament would have more room to escape to the front? So maybe it wouldn't go up? Or am I missing something? (I don't have an UM3, so no personal experience.)

[Nicolinux 288]

Weird, I printed your .gcode file. I had TPU loaded in the first print (AA 0.4) core and nothing in the second (BB 0.4) print core. I did override the warning that the filament does not match. And it really looks like the z doesn't move. I let it print for several layers and the first print core just printed layer over layer. I only heard the sound of the z-screw when the head moved about with PVA (z-hop).

[Nicolinux 288]

Don't know what to make of it. I have the latest firmware as of Feb. 2018.

[fzqxfzqx 0]

Hi gr5 and catg, 

 

I think that might be one potential fault with it, I have some experience with the failed print come out of the bed and stick on the print head. my rationale to rule out this possibility, in this case, was that although it might stick on the print head, the z axis will be moving down, the print will just be drag around the bed, but it shouldn't fill itself up all the way back into the compartment where the cores are as shown in the picture I posted in the first thread. 

[fzqxfzqx 0]

Hi Nicolinux, 

 

Thank you for giving it a try, as something similar has happened to you, I am guessing maybe it is the program. I also use the Feb edition of Cura and the Gcode generated by it without further modification. ( as I send the print directly from Cura to the printer via ethernet cable) 

 

As my knowledge is very limited on the GCode, Would you or does anyone noticed anything unusual about the Gcode attached in the first thread?

 

 

 

[fzqxfzqx 0]

gert 2

 

I think the fan and the bracket is a standard thing come of UM3, i think it is there to help with cooling. it is part of the UM3 design.