Rounded Overhang

Hi everyone, new to the forums here, and I have a problem that i'm hoping someone might be able to help with.

I'm trying to print the popular Baby Groot model found here.
http://www.thingiverse.com/thing:2014307/#made

when I try and print the head the rounded overhang of his chin prints are horrible.
http://i64.tinypic.com/23t3u4m.jpg
http://i64.tinypic.com/2r4opjl.jpg
(black is with supports - Grey without)

I've tried all sorts of things, changing the infill, adding supports, adding denser supports etc, all with the same results. Any time I print say a sphere, the bottom half prints like garbage and the top prints mint.

Anybody know what I'm doing wrong?


I'm printing on a Dreammaker Overlord Pro with hatchbox PLA

Thanks everyone hope someone knows what my issue is.

You could try lowering layer height to 0.1 mm or even lower if possible. Also if you print with more than one perimeter, print outer perimeter last, it should produce better results.

If you use Simplify3D, here's some tips to get better supports: https://www.youtube.com/watch?v=piwKAOOaPKc. Personally I found that lowering the support resolution works better.

Quote:

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Originally Posted by spegelius

You could try lowering layer height to 0.1 mm or even lower if possible. Also if you print with more than one perimeter, print outer perimeter last, it should produce better results.

If you use Simplify3D, here's some tips to get better supports: https://www.youtube.com/watch?v=piwKAOOaPKc. Personally I found that lowering the support resolution works better.

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Thanks for the reply. I tried lowering the resolution to .1 and used 3 layer shell, made everythign worse. Most of the filament just ended up a stringy mess.

I'm not using supports preferably, as I shouldnt have to, this print doesnt require supports, people use supports and infill like a crutch. I did however make sure infill was high enough to print the top of the head, definiitely needs a dense net for that.

When I printed the one with support, the supports werent even touching the model like the whole time, it was a complete waste of filament. got not time for supports.

Quote:

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Originally Posted by VonKlutch

Thanks for the reply. I tried lowering the resolution to .1 and used 3 layer shell, made everythign worse. Most of the filament just ended up a stringy mess.

I'm not using supports preferably, as I shouldnt have to, this print doesnt require supports, people use supports and infill like a crutch. I did however make sure infill was high enough to print the top of the head, definiitely needs a dense net for that.

When I printed the one with support, the supports werent even touching the model like the whole time, it was a complete waste of filament. got not time for supports.

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Is the whole print a stringy mess? If so, sounds weird because lowering the layer height should improve quality. Then again not every printer and their settings behave similarly...

Stringy mess might be result of lower layer height throwing the feed rate off; half the material = less force needed to push filament and with extruders that normally slip, might cause too much material to be output. So lowering the extrusion multiplier could help.

I've bee meaning to print this model too, I'll see how Prusa MK2 handles that part.

It doesn't work for all filaments, but setting the temperature at the lower end of the permitted range, say 195C for PLA, with the right amount of cooling, will improve these parts as well.
But mostly this is a matter of good support building. The best supports are peelable structures such as zigzag supports in Cura. Also Craftware has great support options: https://craftunique.com/craftware
Let me know how it works out.

I'm going to grab the low hanging fruit here and say try supports. Just because you shouldn't have to use them doesn't mean you don't.

And saying People use supports like a crutch seems quite elitist to me. There are many different ways to skin a cat, and if it works, it works. If this was a production/commercial setting, getting the initial run to work using supports, management wouldn't care, as you had a working product. If you then refined the process to not use supports, they would be even happier as you are now saving them money. But wasting time delaying production on the perfectly optimized setup never goes over well. And since you're obviously not doing this for a commercial run, copyright laws and all (and if you were, you would be using injection molding, not 3d printing, given the size of a run you would need to turn a profit), I don't see what the hangup is over supports. Yes, they're a pain to clean up sometimes, and I try to avoid using them whenever I can, but If I need supports, I use them. One of my commercial products I do print I have to use supports, and I do, and I spend the 20 minutes cleaning up the piece.

I read through the comments on the Thingiverse item, and sort of laughed when the originator said supports shouldn't be required.

You have to think about how these FDM printers work - a new layer is "squished" onto the layer underneath it. When you get into an overhang, well, there's less and less to squish onto. Simple as that. This is EXACTLY what is happening in your grey print without supports. Up to a 45 degree slope should be easy peasy, but this model requires far more severe of an angle than that. Have you tested your printer and slicer settings on a calibration model that tells you what your setup can do as far as overhangs?

I don't know what kind of pixie dust the Thingiverse originator has to use with his machine, but if I dared to attempt the model it'd have to be with a lot of supports, a just barely hot enough temp and some pretty extensive cooling airflow, hoping to freeze the filament before it had a chance to droop, whether that droop was onto almost free air or onto the support structure.

Quote:

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Originally Posted by Marm

I'm going to grab the low hanging fruit here and say try supports. Just because you shouldn't have to use them doesn't mean you don't.

And saying People use supports like a crutch seems quite elitist to me. There are many different ways to skin a cat, and if it works, it works. If this was a production/commercial setting, getting the initial run to work using supports, management wouldn't care, as you had a working product. If you then refined the process to not use supports, they would be even happier as you are now saving them money. But wasting time delaying production on the perfectly optimized setup never goes over well. And since you're obviously not doing this for a commercial run, copyright laws and all (and if you were, you would be using injection molding, not 3d printing, given the size of a run you would need to turn a profit), I don't see what the hangup is over supports. Yes, they're a pain to clean up sometimes, and I try to avoid using them whenever I can, but If I need supports, I use them. One of my commercial products I do print I have to use supports, and I do, and I spend the 20 minutes cleaning up the piece.

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I did use supports in the original picture. The black print is the print with supports. And I mean that people use these settings a little too much from what I've seen. I watched a video by the 3d printing nerd and he started talking about not printing with infill and stuff and relying on your printers ability to print overhang, kinda changed how i print, and I've had success with it thus far, this however is definitely a different story, like I said before, I did use supports, but it didnt help.

Yes I have run an overhang test. I was able to get to like 60 degrees before it wasnt acceptable. Its not the prettiest, but its acceptable. not like what my print looks like.

and for some mysticism
https://youtu.be/NnujowpIBqM?t=32s

Fair nuff! And I do appreciate the intelligent, non-combative reply to what be considered an aggressive comment. ;) I totally missed the picture captions too, my bad! Soooo..... ummmm... try thicker supports? ;).

I have gotten a kick out of watching his channel from time to time. Smart dude it seems.

I printed the head and as expected, the result isn't perfect, but good enough for me. Should be fine with bit of post processing.

Sliced with KISSlicer, 0.1 mm layer, 0.45 mm extrusion width, 2 perimeters, supports enabled (support threshold 71 degrees). Printed on Prusa i3 MK2. Material is white PLA (Cel Robox), @205 celsius, with part cooling on. I haven't run any calibration for this material, as I normally don't bother.

Would be interesting to try with another slicers, Simplify3D and Prusa's Slic3r (has 0.05mm quality preset).

https://dl.dropboxusercontent.com/u/...2010.47.40.jpg
https://dl.dropboxusercontent.com/u/...2010.47.50.jpg
https://dl.dropboxusercontent.com/u/...2010.48.00.jpg
https://dl.dropboxusercontent.com/u/...2010.48.08.jpg
https://dl.dropboxusercontent.com/u/...2010.49.22.jpg

Hey that turned out not half bad :) Looks like i'm gonna have to re-tackle this. I tried some filler putty on my original print, but it was going to require lots of work to finish, and the arm was all messed up so since then i've kinda walked away from this one. but There are still a few things I can think of that might help.

I've thought about running a second print on the bed next to it, so that each layer of the groot head has all the time in the world to cool and solidify, while it prints something else. Not sure if this will work.

the supports I used for the one I printed were all the way around the head, so looks like I can get away with less, but i think i'm putting too much heat in one spot.

Is it bad for layer adhesion to be cooled immediately out of the nozzle? i can increase the airflow over my work piece but not sure if that will be detrimental. Or is it better to cool shortly after extrusion?

Thanks, Prusa i3 MK2 does a fairly good job, I'm very pleased with the printer. With PLA, cooling is required if you want good details. I don't know how much cooling affects layer adhesion, but I've been printing structural parts with PLA and cooling always enabled (see here http://3dprintboard.com/showthread.p...ble-3D-Printer) and I haven't seen any problems with layer adhesion.
For other materials, it depends. ABS prints definitely with NO cooling (maybe for very fast layers and bridging), PETG only for fast layers and if you want the best details.

Also I'd say that when printing stuff like Groot, which don't really require the best possible toughness, go with the settings that produce the best surface quality; lower nozzle temp (~190C nozzle) and part cooling. The other end is where the best layer adhesion is required, like the models in here: https://3dlabprint.com/shop/spitfire...3d-cura-ready/. I've printed the Spitfire as it was bundled with the Prusa and the pre-sliced files have settings these settings for PLA: 220-230 C nozzle temp, NO part cooling.