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retraction blobs - how to minimize?


peetersm

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Posted · retraction blobs - how to minimize?

Hi, I am having some trouble getting rid of retraction blobs. UM+ cura 15.02.1 , colorFabb PLA/PHA....default retract settings (tried both z-hop on and off)

Based on my speed print I can see the blobs get larger the faster I print. But on these other two photos I think I am being conservative but still getting a lot of retraction blobs. Should I be tweaking the default settings, or try printing at 20mm/s?

SPEED PRINT

layer height 0.25mm

shell 0.4mm

fill 0%

print speed 30mm/s all to 100mm/s

temp 190

retract speed 40mm/s

retract distance 4.5mm

travel speed 150mm/s

retract blobs speed test

FINE FEATURES TEST PRINT

layer height 0.2mm

shell 0.8mm

fill 20%

print speed 50mm/s

temp 200

retract speed 40mm/s

retract distance 4.5mm

travel speed 150mm/s

retract blobs fine feature test

BALL PRINT

layer height 0.1mm

shell 0.8mm

fill 20%

print speed 60mm/s

temp 200

retract speed 40mm/s

retract distance 4.5mm

travel speed 150mm/s

retract blobs ball

 

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    Posted · retraction blobs - how to minimize?

    I am definitely not an expert but on the first and last photo these look like blobs you get during layer change. If you look at photos in this thread you will notice similar "blobs" as in your first print. Are you using Cura? I am not sure if it can do retraction during layer changes.

    The middle photo shows stringing meaning you need to play with retraction, see here for hints.

     

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    Posted · retraction blobs - how to minimize?

    Have you tried copying the quick print settings of the latest cura?

    One nice setting is to print the outer shell slowly (at 30mm/s) this will reduce the blobs.

    You can also increase the travel speed to 250mm/s it will give better results on the fine feature test print

     

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    Posted · retraction blobs - how to minimize?

    thanks. I agree the speed test (1st photo) is layer change blobs, i think i need to re-read this

    http://www.extrudable.me/2013/04/02/the-myth-of-z-speed/

    but the 2nd one is retraction blobs for sure, those towers should be squares. the stringing is not worrying me too much since it only starts when the tips are really small. but even down on the base you can see large spots where the retraction happened.

     

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    Posted · retraction blobs - how to minimize?

    OK I was able to greatly reduce the stringing by setting

    Minimal extrusion before retracting = 0

    These pictures show the blobs I think are due to retractions, current settings:

    FINE FEATURES TEST PRINT

    layer height 0.2mm

    shell 0.8mm

    fill 20%

    print speed 50mm/s

    temp 200

    retract speed 35mm/s

    retract distance 5.5mm

    travel speed 250mm/s

    retract-Minimal travel 1.5mm

    retract-enable comb=off

    retract-minimal extrusion before retracting 0mm

    retract-zhop 0mm

    retract3.1 blobs fine feature test

    retract3 blobs fine feature test

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    Posted · retraction blobs - how to minimize?

    Those blobs are quite pronounced! Almost looks like part of the model lol.

    A nice sharp Stanley Knife! :)

     

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    Posted · retraction blobs - how to minimize?

    This is where I got the file from, has anyone else printed the "Fine Positive features" file?

    https://www.youmagine.com/designs/make-2015-3d-printer-shoot-out-test-geometries

     

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    Posted · retraction blobs - how to minimize?

    My ultimaker2 prints pretty damn perfect everytime i coudlnt reproduce those blobs even if i wanted to, ive just done some 0.2 layer height stuff and now am doing 0.06. I dont get any weird stuff people complain about. I now always do my shells at 1.2 used to do them at 0.8 but it meant they were a bit to fragile for my liking. And speeds i use are 35, 50, and 70. anytime i get errors, it means i need to clean the nozzle. Dont try to print too fast and expect great results. I also wouldnt waste my time printing tests, your better off trying out new settings on the thing you want to print, rather than some bunch of cubes and weird shapes meant to test the printers capabilities. Just my opinion.

    Also maybe try different filament. Ive have a great time with ultimaker blue pla and black colorfabb pla also. But i see you have an um1 whilst i have a 2. Not sure it matters though as ive heard great things about the um1 that beat eventhe results of the um2

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    Posted · retraction blobs - how to minimize?

    glad your UM2 is working so good. and I agree that printing slower normally gives better quality on surfaces.

    I bet you'll have a different opinion about test prints if you should ever find yourself trying to dial in settings to get a better print quality for a certain model. Test prints use less plastic and in a short amount of time (low print time) they let you focus on the behavior you're trying to correct.

    My printer has been down for a while waiting for replacement parts but I'm hoping to get it running again soon. I think next I will try printing slower than 50mm/s and explore modifying the z speeds.

     

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    Posted · retraction blobs - how to minimize?

    I personally know i am not going to get 'perfect results' but from past experience have realised that its more the materials i use that change things like overhang quality, and things like that as well as temperature. Thats it. I NEVER dial in settings. And i find it truly fruitless printing test pieces. i use the same settings for EVERYTHING i print, and i have high standards, so if i can do it i find it puzzling that other people have so many issues? The only thing i cant seem to totally eliminate are the ringing lines, but i can minimise them in post, and are kind of bound to happen with fdm so i have slowly grown to live with them, but other than that and the occasional nozzle jam thats it.

    I truly see no reason at all for test pieces. I just adjust the temp and speed, usually on the fly during the first print, when i get to what i want ill just stop the print and start fresh after a few layers. Problem solved.

    I wish you the best with your issues, and hope i wont need any replacement parts anytime soon!!!

    I use cura btw and only use the basic settings page. like this. i play around with heat settings on the fly its a lot easier that way.

    Screen_Shot_2015_04_06_at_17_21_14.png

    upload pictures free

     

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    Posted · retraction blobs - how to minimize?

    OK finally got time to look at this again. I'm thinking my issues are resulting from how CURA generates retractions. Some where after CURA 14.12.1 this must have been changed. see the images below of the same object with same settings.

    5a330fab4c9d0_boxsideviews.thumb.jpg.4ea92f4d24169035fe03d1f5942b2fad.jpg

    5a330fab8505c_boxtopviews-4.thumb.jpg.4f8833152c3ed306514a4998b6d07f32.jpg

    5a330fab09ed8_boxtopviews-2.thumb.jpg.059d8bc6152311b7f66d7b589fb42022.jpg

    So I guess my solution is to stick with CURA 14.12.1 for now.

    5a330fab4c9d0_boxsideviews.thumb.jpg.4ea92f4d24169035fe03d1f5942b2fad.jpg

    5a330fab8505c_boxtopviews-4.thumb.jpg.4f8833152c3ed306514a4998b6d07f32.jpg

    5a330fab09ed8_boxtopviews-2.thumb.jpg.059d8bc6152311b7f66d7b589fb42022.jpg

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    Posted · retraction blobs - how to minimize?

    Have you tried copying the quick print settings of the latest cura?

    One nice setting is to print the outer shell slowly (at 30mm/s) this will reduce the blobs.

    You can also increase the travel speed to 250mm/s it will give better results on the fine feature test print

     

    Pardon me, but I respectful ask ,,, How was this set as the best answer? I thought I was supposed to be able to pick the answer for the questions I post? Another strange issue (kind funny) is that I did not even get a notification that this question was answered? Please unflag your post as the best answer. I think the answer may be my most recent post 7-22-15. thanks

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    Posted · retraction blobs - how to minimize?

    The author of the subject can set the best answer and moderators too. We have to go through "old" unanswered questions once in a while and try to figure out the best answer if the post looks like it's answered but the author forgot. This is for future users that run in the same problem.

    Your recent post is now set as the best answer ;)

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