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evilgrass

Hello from Utrecht, Netherlands

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Hello all,

I received the Ultimaker as a gift. Assembled it without problems - the wiki documentation was extremely clear, thanks! The printer printed excellently already without any calibration (and without me knowing anything about calibration too...). I just opened Cura, did the wizard, after which it sent me to that Ultimaker robot model and I just hit "print", that's it.

There's only one problem, not a very serious one, but still: it seems that before (when heating up) and after printing (when the head is still hot), filament comes out of the head without the extruder moving. As a consequence, often my prints have random filament blobs, consisting of filament that came out of the head while it was heating up, attached to them. Moreover, it seems that because of this filament loss during the heating and cooling phase, there's too little pressure when the actual print starts, such that the first line it tries to print is often very thin or nonexistant. Again, it's not a serious issue; it seems to usually solve itself during the print, and any random filament sticking out I can easily remove afterwards, but I'd still like to solve it if possible. Any advice?

 

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Hi,

I know this issue as my printer also start "printing with hot air". Honestly I have alo no idea why. I already tried to add a few mm in the start.gcode but that was also not the perfect solution.

My startup code now looks like this - how looks yours?

;Sliced at: {day} {date} {time}

;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}

;Print time: {print_time}

;Filament used: {filament_amount}m {filament_weight}g

;Filament cost: {filament_cost}

G21 ;metric values

G90 ;absolute positioning

M107 ;start with the fan off

G28 X0 Y0 ;move X/Y to min endstops

G28 Z0 ;move Z to min endstops

G1 Z15.0 F{travel_speed} ;move the platform down 15mm

G92 E0 ;zero the extruded length

G1 F200 E5 ;extrude 5mm of feed stock

G92 E0 ;zero the extruded length again

G1 F{travel_speed}

M117 ;Printing...

Maybe someone of the experienced users could assist here too?

 

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You can prime the print head manually before starting a print by turning the big gear by hand until you get a consistent extrusion. When I do this, I try to cut the oozing stringer off at the nozzle as the print head traverses to the start point of the print. I use an opened scissor or screw driver or exacto knife - whatever is handy. Just stay out of the way.

Another thing you could try is to enable the skirt function. If you have skirt turned on, priming the extruder manually is maybe redundant. Skirt will print a single layer thickness 'border' around the bottom of your print at width you define. This will normally be 6 or more concentric loops starting away from and ending at the outside shape of your part. Since its the first layer, it prints the skirt on slow speed and give ample time to establish a properly primed head (and properly adjusted Z screw) before the part is started.

 

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I underscribe Mastory's method. It's not sophisticated, but trust me on this, hardly anyone starts a print and walks away. There are several suggestions and idea's to solve this matter.

If it gives you (all) some comfort, at work we have a €30.000,= Rapid prototyping machine, containing two heads (a Dimension) which does excactly the same. Therefore there is a steel brush with a container screwed in the backside of the machine, were it always starts tot wiggle for a few seconds, while extruding both filaments.

If there is a certain amount of time passed between changing filament, it will repeat this procedure. Hopefully, there will be a sort of solution for this problem, but in the mean time you should use the Brim feature. In the older versions of cura it was called skirt with a slightly different behaviour. If you are planning a large object, you should take in conideration to lower the value in Expert settings, otherwise Cura will not slice it.

Welcome here, especially residing in Utrecht:-D

 

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like the above posters. I ususally preheat, and then turn the gear that says extrude-> in the direction of the arrow until you get a nice stream and just take off the excess with tweesers right before the bed starts moving. That, combined with a 1 line skirt seems to make everything go smoothly.

I usually watch the first layer. If it's perfect you can usually walk away assuming there are no tricky parts on your print. If the first layer is iffy, Ill watch 2 and 3. and stop if required.

It's almost like a print ritual now..

 

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Hello all,

Thanks for your replies! I tried extruding using the Jog fuction in Cura, but that didn't help too much I think. The skirt function is on, I think, because before starting to print, it prints a line around the model. Maybe I should make it print more of those. I mean: I don't really mind wasting so little material if that makes the blobbing go away...One thing though: in my version of Cura I have both Skirt and Brim. Which one should I use, and what's the difference between the two?

and @drayson: I haven't changed the default code at all. So it's just the same code as when I opened up Cura for the first time:

 


;Sliced at: {day} {date} {time}
;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
;Print time: {print_time}
;Filament used: {filament_amount}m {filament_weight}g
;Filament cost: {filament_cost}
G21 ;metric values
G90 ;absolute positioning
M107 ;start with the fan off
G28 X0 Y0 ;move X/Y to min endstops
G28 Z0 ;move Z to min endstops
G1 Z15.0 F{travel_speed} ;move the platform down 15mm
G92 E0 ;zero the extruded length
G1 F200 E3 ;extrude 3mm of feed stock
G92 E0 ;zero the extruded length again
G1 F{travel_speed}
M117 Printing...

I could indeed tell it to extrude more than the 3mm it already seems to extrude in the beginning.

Thanks for all your tips! I'll start experimenting a bit and report back if I get good results!

 

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skirt just shows you, there's plastic coming from your nozzle and sticking to your bed. Excellent moment to adjust your Z-axis one or two clicks if nescesary.

Brim does the same thing, untill almost at your oblect, clamping to it, so you'll help the object not to warp sharp corners or edges. If you have the choice, I'll stick to the brim.

 

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