UM Original Hot End Problem

[onkelgeorg 36]

Hi all,

since a couple of weeks I have a strange problem on my UMO hotend.

When the filament cooled down after a print and is re-heated I have massive problems to remove it from the print head. There is massive pull required to remove the filament.

If I leave the filament in the hotend and start a new print there will be no material flow until I remove the filament, cut off the slightly thicker end (with a small rim at the end) and re-install the filament. After this procedure the print runs without problems.

This problem haven't occured within the first 6 months of printing. So I think something must be wrong inside of the hotend. There are no leaks or broken parts visible...

Any help is appreciated

Cheers,

Joerg

 

[peggyb 169]

I guess this has to do with the teflon part. Yes, this also happens to the UMO… at the connection with the peek a little bit of material disappears. When you take the hot end apart the teflon has a brown brim.

Or there could be a little gap between the hot end parts bowden-teflon-peek-brass, not necessarily ending up with leeks.

Evidence can be seen when you pull the pla and see a thicker part at the end.

 

[onkelgeorg 36]

Hi Peggy,

thanks for your reply. That is exactly what I was afraid of.

Shouldn't this part last longer than 9 months?

 

 

[IRobertI 516]

First check that it isn't simply that the parts have separated slightly. Take the hotend apart and re-assemble, making sure each part is mating properly to the others and try again.

 

[peggyb 169]

here is a picture of the old teflon part, normal use-a few times a month, about one year old.

and a before and after changing the teflon

 

[onkelgeorg 36]

@Robert: Thanks for your answer, I will check it this weekend. Hopefully it's just a loose connection, but...

@Peggy: Thanks for the images. After seeing the second image I am almost sure that the Teflon is damaged. My last prints looked pretty similar to your "before" image

 

[onkelgeorg 36]

btw: I am considering to ask a friend with a lathe to produce some of this parts. But unfortunately the measurements in the technical drawing of this part #1055A2P-B are not complete.

Does some have the complete measurements of this part?

 

[IRobertI 516]

There's a STEP file provided, import that into your CAD software of choice and you can get the measurements that way.