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kurt

Poor extrusion only close to feed (back right)

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When printing I get a poor extrusion only in the corner of the machine near the feed mechanism. This is noticeable on all larger prints (>100mm diameter). Each layer is poor in this corner but the extrusion is fine in the others. The problem is particularly noticeable on the perimeter. Is it possible that the movement of the head is causing the material path through the bowden tube to change length causing uneven extrusion rates ? Has anyone else experienced this? Did you fix it? How?

Kurt

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This is a picture of the problem. About 1/4 from the bottom I moved the feeder to the middle of the right side of the Ultimaker. You can see that the sparse extrusion followed the feeder. I moved it back to its normal mount after about 10 layers and the sparse section of extrusion followed.

IMAG0925.jpg

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How fast are you printing? That looks a lot like my print when I got near the maximum extrusion speed. Maybe if you drop the print speed by 10-20% it will print fine.

The "curve" of the bowden tube might be causing this, putting a little bit of extra stress on your extruder. Some extra tension on the tension knob might help, some higher temperature might also help.

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Thinner layers would also help. Anything that would reduce the "mm^3 per second" would help (slower, thinner), and or anything that will increase the flow trough your nozzle (more heat)

Better temperature management (AKA PID controller in Marlin) will also help I think.

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After printing for about 30 min at 100mm/sec voids started to appear near the front left of the machine. This probably throws out my bowden tube bending theory.

I slowed to 50mm/s and completed the print successfully.

The tension has been significantly increased so that it is a little difficult to slide the tensioner lock arm down.

I am using a Marlin firmware and the PID temperature control holds within 1C whenever I check.

Any ideas for removing the gaps with faster print speeds? I attempted to use retraction_extra to force more material through after a rapid movement. my hypothesis is that a long move causes a string which drags some material out of the nozzle so the start of the next extrusion-move doesn't get enough flow. This hasn't appeared to make a difference but I only tested one setting (settings below).

Thanks for all the help thus far.

complete1.jpg

complete2.jpg

SkeinPYPY settings:

 

[profile]filament_diameter = 3.02nozzle_size = 0.5machine_center_x = 100machine_center_y = 100layer_height = 0.2wall_thickness = 0.5solid_layer_thickness = 0.8fill_density = 25skirt_line_count = 0skirt_gap = 6.0print_speed = 50print_temperature = 230support = Nonefilament_density = 1.00retraction_min_travel = 5.0retraction_speed = 30retraction_amount = 0.1retraction_extra = 0.3travel_speed = 300max_z_speed = 1.0bottom_layer_speed = 25cool_min_layer_time = 7model_scale = 1flip_x = Falseflip_y = Falseflip_z = Truemodel_rotate_base = 0model_multiply_x = 1model_multiply_y = 1extra_base_wall_thickness = 0.0sequence = Loops > Perimeter > Infillforce_first_layer_sequence = Trueinfill_type = Linesolid_top = Truefill_overlap = 18support_rate = 80support_distance = 0.5joris = False

 

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After printing for about 30 min at 100mm/sec voids started to appear near the front left of the machine.I slowed to 50mm/s and completed the print successfully.

The tension has been significantly increased so that it is a little difficult to slide the tensioner lock arm down.

Too much filament tension is counter productive, since it deforms the filament and causes other problems. also, the more tension, the smaller the effective radius of the bolt gets, and the less extrusion you get.

 

Any ideas for removing the gaps with faster print speeds? I attempted to use retraction_extra to force more material through after a rapid movement. my hypothesis is that a long move causes a string which drags some material out of the nozzle so the start of the next extrusion-move doesn't get enough flow. This hasn't appeared to make a difference but I only tested one setting (settings below).

SkeinPYPY settings:

filament_diameter = 3.02

nozzle_size = 0.5

wall_thickness = 0.5

as Dave said, 3.02 sounds a bit thick, and if your filament is thinner, you are setup for under-extrusion.

assuming your object is 1mm thick? fixing the tension and the diameter should help.

you can also do live-tuning in printrun:

type in the lower right M221 S110 and hit return. a couple of seconds later you should see a slightly thicker extrusion. if not use M221 S120 (20% extra) etc until you are there (m221 is the extruder, m220 is the overall speed adjustment. in addition, use M104 S220 (220C) to adjust the temperature (down) (takes about 10-15 sec to reach the new value, but the print will continue)

once you have satisfactory values, wright them down, and adjust your slicer settings for the next run, and don't forget to reset your printer before the next print.

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Your problem looks very similar to a problem I have. In my case it is caused by the end of the brass nozzle not being flat, but cut at an angle. I have not gotten around to fixing it yet, but I plan on sanding it , I will also need a 0.4mm plunge (such as a drill bit) in order to make sure there are no burs left inside the nozzle after sanding.

N2HVC.jpg

TsyPI.jpg

This is more easily visible with the eye. Some feed/flow settings will make the problem more or less obvious.

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MM_Build, Interesting information. I have a MK3 0.5mm nozzle with a cut down tip. It is possible that its not flat. When it extrudes material in the air the stream tends to go to one side.

At 50mm/s, 230 C and after rerunning the 100mm extrusion calibration in skeinpypy, an 8 hour build completed successfully without the holes. Thanks for all the help. Now I have to order more PLA.

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I feel it necessary to update.

I have eventually concluded that my mangled nozzle tip is my own dumb fault. When I first started I was using a pair of needle-nosed vice grips to clear excess extrusion from the tip, and I am almost certain I had grabbed the tip accidentally at least once. I would just like to clear ultimakers name in case I implied that's how they send stuff out. Newbies make mistakes they don't even realize! :)

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