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Printing issues ->dripping
#1
Hello,

My first print after repetier 0.91 install and manual calibration I get this kind of chrismas ornament print. I set 0.2 layer with 40% in fill.

Honestly I think the first inch is amazing, look at the picture, then suddenly molten abs started to drip and I finally stopped it. I noticed that the extruder header was not anymore over the last layer but in fact little bit lower and this was putting pressure on the bed. its like the print head was pushing the object from the top an causing the drip.



Anyone could explain?

thanks[Image: 20141210_142705.jpg]
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#2
I'm no expert and I haven't used repetier, ever. So what ever I say, I may be totally wrong Smile

It looks to me that your steps per mm for the z axis is slightly out. i.e. too low. This has a cumulative effect, the nozzle gets closer and closer to the previous layer. So you start at 0.2mm between layers and gradually get to 0.1mm (or something like that) but still extruding an amount of ABS for 0.2mm. The ABS squeezes out around the nozzle and the nozzle just moves it around. At the edges it droops (drips) over the side.
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#3
Have a look at this thread Repetier X/Y/Z Axis Stepping - calibration. It might help.
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#4
Thanks for your answer,

I have made the measurement as per calibration thread and i get 2560 but it was already set to that microstep.

Very strange I can build a simple cylinder of 10CM high and it is perfect but for complex shape it always drips...

must be something else.....
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#5
I have found that it has to do with the extruder hotend. The Da Vinci extruder keeps so much of the heat near the print while printing that it keeps the plastic molten for quite some time after it has been laid. As you have found though this isn't an issue for simple parts with no over hang, but as soon as any over hang > 20-30 degrees is introduced the prints come out horrible. I have tried everything I can think of to correct this but haven't found a solution that is acceptable so I am ditching the stock hotend in favor of an e3d v6.

The thing that made the biggest improvement for me though was to run the extruder at 230 C and the bed at 95 C, do layers of .3mm, add a z retract of .5mm on rapid moves, and speed up the print significantly. This brought the best results on complex parts with overhangs like the one you are trying to print.
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#6
what is the size of the object ? it is small enough that you can print 4 at once ?
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#7
Diameter is about 2.5 inch, If I understand, you are proposing to make 4 at one layer would have time to dry. Interesting.
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#8
Yep thats it. a rule of thumb for things this small is the longer you can let the layers cool before the next the better.
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#9
If you're using slic3r you can add this code under Printer Settings tab->Custom G-code->Layer change G-code

G1 E-1 ; retract filament to stop drips from extruder
G4 P1000 ; (dwell) pause for 1 second
G1 E1 ; unretract filament

Slic3r will add these 3 lines on each layer after the Z has been moved ready for the next layer. So the printer will finish a layer, move Z by 1 layer height, pause for 1 second, start printing the layer. It will mean the print will take longer but it may stop the drips.
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#10
cura and slic3r have a setting for minimum time layer, which slow down the speed and even do a pause if time is too short

but i always found print several copies give better results as it does not slow down the flow
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