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Huge PLA leak above heater block UM2+

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Having used my Ultimaker 2+ purchased form you in December quite successfully for many weeks, I had a major problem develop with it during a print yesterday.  I left the machine running for a few hours and came back to it to find this.


The first photo shows the hot end after I partially disassembled it quickly to avoid it all sticking together with hot PLA.

The PLA has leaked above the Olsson block and formed a large block of PLA around the Olsson heating element and the temperature sensor.
By heating the block carefully after disassembly I have managed to free the PLA block and isolate all the components.
I am not sure how this could have happened other than perhaps a mis-manufactured Olsson block causing a leak to due the flat plane onto which the nozzle sits not being perfect.
The 0.4mm nozzle in use had been in use for several weeks with no problems and daily prints.  The nozzle was tight and checked while cold after being inserted and tightened whilst the block was still hot.  The PLA definitely leaked out above the Olsson block.  The metal feed collar and the PTFE feed collar are in good undamaged condition.  However the metal collar has solidified PLA around its threads.
The PLA is Innofil blue purchased from your company and not previously caused any problems.  Never had any leaks before!
The issue i have now is that the heating element and temperature sensor have hardened PLA on them.  The Olsson block, although I have tried to clean it off, is coated in a layer of PLA and therefore I cannot re-use it as it will burn onto the block.  All fans and the other hot end components are fine.
Can anyone suggest how to rectify the problem of the PLA coating components?  I think I will need a new wiring loom back to the mother board due to the PLA on the heater and sensor, a new Olsson block and a new metal feed collar to screw into the Olsson block.  Also probably a new nozzle due to bad burn in of the nozzle after the leak encased it.
Edited by itserve

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Managed to completely clean the block in a glass dish of boiling water.  Did the same with the nozzle external thread.


Then went back to the printer, raised the bed and placed the dish of water on the bed to immerse the heater and temp sensor (with temp set to zero).  This enabled me to then carefully pick off the PLA from those.  reassembled, heated to 260 degrees to tighten the nozzle and now I'm doing a test print.  Will post the result!

Edited by itserve

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This usually happens when your part is wider than tall and then when it comes loose from the bed.  At that point the nozzle is dragging around your print like a hockey puck and filament is still coming out and it has to go somewhere so it goes "up".


The solution is to keep your part sticking to the glass.  I could tell you how to get your part to stick to the glass but it's better to also know why the techniques work because then you can modify the techniques.  So to become an instant expert you should really watch this entire video (sorry it's so long but it contains the results of many experiments and I tried to keep it short):


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Thanks for all your responses.  I use hairspray to get things to stick and usually it's absolutely fine.  I was having a few issues with this large based bowl though - some lines just weren't laying down properly.  Then the problems happened!  I guess it could have gone up past the shield and above the print nozzle - now its all fine though and my test print worked fine.  I will be watching the video to see what more I can do to get the larger based pieces to stick.  I had thought perhaps a higher bed temperature.  The lump of PLA made the metal shields of the fan enclosures bend too, and scratch the side  of the printer. All bent back no problems and looks fine again, just a few scratches.


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Hairspray is excellent.  The next of a few tricks you need to do is to squish th bottom layer more.  Maybe.  although that print I see there looks like the skirt is transparent so you probably squished it quite well.  The next trick would be brim or rounded corners which you got on most corners but the top branch of this part not so much.

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