Weird TPU95A tearing problem (Ultimaker S5)

[covers911 0]

Hi,

 

As can be seen in the photo, I'm experiencing a weird problem when printing Ultimaker-brand TPU95A with my S5 (using Cura). The print just tears off when I attempt to remove it from the glass plate - and it's not because the adhesive is too strong. There is a strange stippling to the third or fourth layer of the print, as if there are tiny holes in it, and it is weak BEFORE I remove it. The rest of the structure is perfect!

 

This is driving me up the wall. I have never experienced this before. Has anyone any idea what's going on?

 

Thanks.

[Smithy 1,141]

Do you also see this "strange" layer in the preview?

[covers911 0]

11 hours ago, Smithy said:

Do you also see this "strange" layer in the preview?

No, I see nothing different about this layer in the slice preview. This is so confusing.

[Torgeir 228]

This look very strange, seems to happened just after first or second layer(?).

 

I've put a little more brightness and zoomed in some here:

Put in some lines to mark some issues.

The line at the bottom shows "much under extrusion", the tree lines above; -is this something to be there "in this object"?

 

 

 

 

I'll think you need to tell us a little more how this happened(?).

Did it occur after some change to the printer, -or in the Cura slicer, -or profiles?

Do you use the same core for more than one type of filaments (PLA , TPU95A etc.)?

Did this happen with other kind of print object (known good from before)?

 

Edit: Just come to think about if this could be an issue because of some high nozzle pressure during first layers (with soft filament), this condition might lead to grinding some and low flow when pressure decrease. Actually, this might be easy to see if you study this printing in the beginning by monitoring the feed.. 

Hmm.. Just a shot..

 

Thanks

Torgeir

 

 

 

Edited November 4, 2020 by Torgeir
More info.

[covers911 0]

Hi Torgeir,

 

Originally, I started to experience under-extrusion problems when printing TPU. I tried various things to solve the problem, including: using both feeders for TPU, cleaning out the feeders, adjusting the tension of the feeders, switching the flow sensor on/off. The S5 now does at least complete the print (without the 'One material appears to be empty' error) with the flow sensor on, but I can't get rid of this problem.

 

Attached is another image showing what a print looks like before I remove it from the glass. You can see that there is over-extrusion of the first(?) layer, and then layers 2 and 3(?) have the stippled appearance with holes. What do you think?

 

 

Edited November 5, 2020 by covers911

[Torgeir 228]

Well, soft filament is really a demanding task for bowden tube printers.

The art is to print with as lo resistance as possible needed for proper feeding of this kind of filaments..

Ultimaker advice to dry TPU95A before printing, -did you perform this recommendation?

The TPU 95A profiles are "optimised to print on a cold build plate on the Ultimaker S5", so in order to validate this you'll need to deselect core 2, -if not the heat bed will go to default 70 deg. C.

 

Use glue, then reduce first layer width to 100% (default is 120%). Reducing nozzle pressure during first layer printing.

Do not use high printing speed, around 30 mm/sec. You may test a little to find the best speed.

Retraction, here use a little as possible..

 

Well, this is my 5p.

Good luck

 

Thanks

Torgeir

[covers911 0]

I still cannot solve this. I used to have no problem with TPU, and now it ruins every print. For the life of me, I don't understand what suddenly changed. This problem did not gradually develop. It was sudden.

 

I've tried everything I can think of, including calibrating the leveling, trying a different reel of TPU, taking the feeder apart, adjusting the width of the first layer... nothing works.

 

What's the next stage? Should I buy a new feeder mechanism perhaps?

[Torgeir 228]

Sorry to hear this.

 

This is strange, -so do you print other filaments using the same print core?

A clean print core is important for printing with this "soft" filament..

Also for all the "exotic" special filaments I have found that, it is advantageous to use a nozzle or print core only for that type of filament.  Soft filaments and high temp filament's require some "special attention" - for the nozzle/print core you're using -and is often in the "experimental" class of 3D printing.

 

So, if you're printing different material it's important to make sure that the nozzle/print core is clean.

 

The most important thing when printing "filaments" known to be humidity sensitive is to STORE the filaments properly.

Most of the high sensitive filaments will be contaminated on the outermost part of the beginning of the roll, so unwinding this part "say one meter" and cut it off.

 

The cleaning procedure is here: https://support.ultimaker.com/hc/en-us/articles/360011652559-Print-core-cleaning-maintenance-schedule

 

IMO., the above is the most common problem we'll see in our FDM 3D printing.

 

Hope this help you somehow.

 

Thanks

Torgeir

 

[covers911 0]

Hi Torgeir,

 

I'm quite convinced that something must be wrong with the Z axis mechanism (i.e. the leadscrew). Perhaps a great deal of force was used to pull a print off the plate.

[Torgeir 228]

Is not this happen only when you're printing TPU95A?

A problem with Z axe will be visible with "any" type of filament..

 

Torgeir