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Pressure ? Blockage or am i just stupid ?

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Pressure ? Blockage or am i just stupid ?

Ok this is my problem I am using for the moment Cura4 and using the simple standard print defaults.

Now when I print, the printer starts, heats up to 210 with PLA.

Prints fine for about 5 minutes until i start seeing the Bowden tube life out of the print head.

I marked the Bowden tube where it was going onto the print head ontop with a black marker and now every time, i print, ever thing worls ans then that black mark springs up, i see a big spcae between the bottom print plate and the top plate.

About 30 seconds later, the print starts to fluff and you know there is no filament getting pushed into the print head.

So here are a few ideas why this is happening ?

(1) my extruder is pumping the filament way to fast, so it cannot get through the print head and so, as a counter action to that build up of pressure, the Bowden tube gets blasted backwards. there fore ending the project !

(2) The print head copper element has small amounts of residue from previes blockages and some how building a blockage wall for the new filament ?

(3) Im printing to close to the work surface and the filament doesnt have a chance to get out of the print head, and so causes the bowden tube to blast out of the box?

(4) The bowden tube is a little scratched and slows the flow of filanet, there fore allowing the extruder to pump a little to much material and after 5 minutes of build up, then bang !

(5) The Bowden tube is short and so under extreme tensiion, with the motion of the ultimaker, this tension works the Bowden tube out of the print head ?

Ok thats every idea I have at the moment.

Im going back to my office and try cleaning out the print head one more time and try printing something easy... 7 minute normal cura model ?

and hope this one doesnt crash..

recorded successful prints today.... ZERO but lots of plastic stink ;-)

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Clearly it prints something before the tube pops out so there cannot be a blockage.

Do me a favor and calibrate your E steps/mm and measure your filament diameter before starting the next print. Just FYI the method of calibrating E steps/mm is to measure the amount of filament taken in (distance to a line drawn on incoming filament) WITH the hot end still connected and at temp (you are measuring how much filament is being taken in by your extruder under operating conditions).


ever thing worls ans then that black mark springs up, i see a big spcae between the bottom print plate and the top plate.

Please expand on seeing a big space. Where do you see a space? Is it between the aluminum plate and wooden parts of the head? Are you suggesting that this space forms as a result of the bowden tube popping out?? I find that highly unlikely.

How far up does the black mark go? See this thread viewtopic.php?f=7&t=987

How short is your bowden tube? It should form a half-circle above the UM most of the time. If it is too short then yes that is bad.

What have you done after it pops out? Did you just put it back in or did you cut it off?

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thank god its not the filament.

I rechecked by E step number and by changing it to a higher number 105mm, the filament was pushed much slower through the bowden tube and has after 3 hours now printng, not caused any movement from Bowden to print head.

so fingers crossed that was the main cause.

Thanks guys for the tips and ill keep you guys posted !

Best wishes.


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