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Issues with first prints

Posted by matrix4721 
Issues with first prints
October 14, 2013 06:19AM
Hi all, ive just completed building my prusa i3 and have started printing, hurray, printed a cube and it came out fine so i thought i would be more adventurous and printed an owl, however there are afew print quality issues that need addressing. As you can see from the pictures there are blobs on the weathers and on the head and sagging under the chin, any ideas on how an i fix this? ive already calibrated the extruder steps so that should be fine. Kind regards, Chris
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Re: Issues with first prints
October 14, 2013 09:07AM
I have things like this too.. Filing/'wedging' them off leaves makes it visually look bad.(The latter less so i think it turns much lighter because of much more granular surfaces when you file)

According to this,("Your object has lots of beads on the sides") it could be due to overextrusion, but i am not sure. It seems that changing my extrusion width to 0.3mm improved things, but not totally.. (The shop says i have a 0.5mm extrusion hole, (note that it seems the value in the slicer doesnt have to be the same) Earlier i used `--extrusion-width` the default. (It doesnt say what it is, well it says '0' but that means it uses some factor of layer height i think)

Sometimes it seems due to speed changes.

Anyway, interested in what others say.
woo
Re: Issues with first prints
October 14, 2013 09:19AM
check your retract value, if there is everything ok, check if stepper motor maybe skip steps due to high retraction acceleration.

also its ok to check fillament diameter and also if extruder is calibrated good...
Re: Issues with first prints
October 14, 2013 10:57AM
Thanks for your answers, heres my marlin settings regarding retraction

#define DEFAULT_MAX_FEEDRATE {500, 500, 2, 45} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {9000,9000,100,300} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

#define DEFAULT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 300 // X, Y, Z and E max acceleration in mm/s^2 for r retracts

Not sure if there okay or not as im not sure what they are supposed to be, the extruder is nearly smack on, i tell it to extrude 100mm and it extruders 100.3mm. The only other thing i can think of is temperature. I have mine set at 240 degrees C while using abs, i have it at this is reduce the amount of back pressure as i use a direct drive bowden extruder, could this be affecting it?

In regards to the filament diameter, im using 1.75mm filament and it is set as 1.75mm in the settings however, it actually measures 1.79mm, should i change it in the settings or doesnt it matter? thanks, Chris
woo
Re: Issues with first prints
October 14, 2013 12:11PM
yes, it matters. change it to 1.79. you are giving your printer more material then he thinks....
Re: Issues with first prints
October 14, 2013 05:51PM
Okay, ive changed the filament diameter in the settings and reprinted the owl but the blobs and tatty head still remain. Could it be the retraction? If so how would i change it to make it better? is it the retraction acceleration?
woo
Re: Issues with first prints
October 14, 2013 06:39PM
i have max acceleration for extruder set to 15 000. works for me confused smiley
Re: Issues with first prints
October 14, 2013 09:02PM
I realized that some of the issues I am seeing is due to this.. Probably doesnt explain matrix4721 issue. All i have got on that is, try changing extruder width? No signs of ooze, right?
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