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Re: over extrusion on first layer

Posted: November 27th, 2017, 11:33 pm
by newjeeper369
I apologize if it seems like i am asking for a "magic answer" or "one size fits all settings" i really do appreciate any suggestions or guidance. The truth is im am very busy lately and dont have much time to play with my printer as i would like, so when i do have the time i like to have some ideas of my own and or suggestions from you guys to efficiently use my time when i encounter issues.

Re: over extrusion on first layer

Posted: November 28th, 2017, 7:58 am
by Roberts_Clif

I had a problem like this once and found that the PTFE tubing in the throat had deformed.
If you have PTFE lined throats you may check that?

Re: over extrusion on first layer

Posted: November 29th, 2017, 11:32 am
by Roberts_Clif
GrueMaster wrote:
November 27th, 2017, 11:09 pm
AFAIK, based on the specs of these two printers, other than one shipping with an auto level sensor, they are the same. I do know they use the same extruder and print head. The fact is, they print with very different settings.
Other than Blu with a 24V supply and T8-8 lead-screw (8mm pitch per turn) and Red with a 12V supply and T8-2 lead-screw (2mm pitch per turn) both printers are upgraded exactly the same. Both running on a single APC UPS 725.

Not sure how to help if your 3D printer prints one day perfect, then the next day over extrudes. Not much to troubleshoot with.
Do you have an external source of air blowing on the machine, Do you have 120v AC power that varies high one day the lower the next?
Here at the Hanford Reservation power can vary one minute from 90vac to 120vac the next minute.

Do you have more information you can give us in order for us to help you with.

Re: over extrusion on first layer

Posted: November 30th, 2017, 7:22 pm
by newjeeper369
I think it might have something to do with the nozzle, throat or heating element. I heated the hot end to 210c and feed a good bit filament through and then removed the filament and reinstalled it. tried a test print and it seemed to be printing okay so i stopped the print, then i started a new print and the issue returned.

I then continued by taking the hot end assembly apart and i found the set screw holding the heating element in wasn't tight at all. i inspected the throat and i didn't see any clogs or issues with the PTFE tube. i cleaned the nozzle out the best i can with out the proper cleaning tools.

during reassembly while tightening the throat or Extruder tube it broke in half, i have new tubes, nozzles and cleaning tools arriving tomorrow.

I will update hopefully tomorrow, i am mildly confident the new nozzle, throat tube and tightening the heating element will fix the issue.

Re: over extrusion on first layer

Posted: December 6th, 2017, 8:15 am
by newjeeper369
Sorry for the delay.

i installed a new .4 nozzle and extruder tube, unfortunately the issue still exist.

I had a few hour late one night to look into to the issue and im not totally sure it is over extrusion as a previously claimed.

It seems like the Z isnt increasing enough while printing. As a result during infills, especially in smaller sections of the print where the extruder is making very short movements. i believe it is giving the appearance of over extrusion but with closer inspection it appears the nozzle or Z height is the issue.

In a attempt to prove its a Z issue i lowered the flow to ~54 percent via the print GUI and started a test print of a 20mm test cube with xyz letters on the corresponding faces. the result was the first layer was okay, under extruded but still usable, the second about the same as the first, the third you can start to see the Z issue too low giving the appearance of over extrution. then the in fill started, i believe i had it set to 25 or 30 percent infill. the infill lines were thin but again you can see the Z was too low causing the infill and wall lines to be smashed down a bit by the nozzle.

finally the last 3 layers consist of the same issues above, except the top has the letter Y. while doing the infills in the latter is were this issue really showed its ugly head. during the as described above while "the extruder is making very short movements" the nozzle was too close to the print and knocked the print off the build plate.

My thoughts:

first layer height. --- my fisrt layer height is .3, as i learned this is typically wrong and could be problematic, although this setting was working for me before as stated early in this thread. i do plan on trying lower heights.

extruder Cal.--- i did spot check and it seemed okay, possibly a few mm off, but like i said the printer was working great before. and this is a setting in the firmware so i cant imagine it changing on its own or accidentally for some reason. I will do a proper cal. to zero it in.

mechanical stiction of the Z assembly--- my x axis is level and maintaining level through travel of the Z axis. so im am not sure what could cause the Z to have stiction.

incorrect z motor stepping--- (same as extruder Cal.)

bed level, nozzle height or homing issue--- this is pretty straight forward but i am open to suggestions or thoughts. what nozzle height do you guys use when leveling your bed and setting the nozzle bed distance?