i3Mk2 - PLA warping on top of support - mid print not bed  

Re: i3Mk2 - PLA warping on top of support - mid print not bed

I would add 2 Interface Layers in the Support section to give something for the print to stick to.

Re: i3Mk2 - PLA warping on top of support - mid print not bed

Tricky print that. There's not much support area for the actual objects surface to sit on, so chances it'll start curling upwards are very high. You can fight curling by printing cooler and increasing fan speed (if not at 100% already), but there's limits to how effective that is.

I'd try printing this the other side up And add more support. This is one of these parts, where Simplify3Ds fully customizeable supports are worth the price imho.

Also, i don't really like the looks of how it printed your supports. How fast are you printing this? I'd try slower..

Re: i3Mk2 - PLA warping on top of support - mid print not bed

Thanks for the advice guys

I had tried printing it the other way up but when it gets to large surface on supports the same curling at edges occurs

I'l try again with the interface layers - I'd not noticed that option

Re speed - I'm using the default prus pla settings but dial back the speed on the first couple of layers to about 70% as that seems to help bed adhesion (in fact print quite difficult to get off bed now)

Also by adding more support do you mean alter the angle, pattern , density or all of the above 🙂 ?

Re: i3Mk2 - PLA warping on top of support - mid print not bed

I have the met the same issue and made some posts about it too.

The only thing that fixes it for me, is to reduce printing speed to 50-60% duing the problematic parts, with the knob on the control unit/display

Maybe you can try one of the "air duct ring shaped things" on thingiverse, but slowing down was what helped me.

I'd love to hear other options to deal with this, maybe slicc3r settings or whatever, but have not yet found any other solution.

Re: i3Mk2 - PLA warping on top of support - mid print not bed

Yes, slowing the whole print down then allows more cooling time and helps prevent warping.

Peter

Re: i3Mk2 - PLA warping on top of support - mid print not bed

This is an issue, which is difficult to cope with in general.

The sharp overhangs will curl up no matter what you do. Thin overhangs will curl up certainly. You can print cooler, use more powerful cooling, print slower (but too slow means the print head spends more time touching the overhang), but this effect may only be reduced to some extent.

One way to somehow work around this issue is to use Z hop and to have a support high enough around the supported island, so as the island gets nudged by the print head due to the curling and due to an insufficient contact with the support, it stays inside a support "craddle" surrounding the island. AFAIK only kisslicer offers to add a couple of additional supports around/above an island to create such a "craddle". Other slicers achieve such an effect by a coincidence only.

Another way I plan to test one day (probably a software change would be needed) is to deliberately hard anchor the island to the support. This means here will be scar on the object, but the anchor should keep the overhang down. Usually at least with PLA one tries to avoid the scars by dropping the threads of filament lightly over the support so they do not bond at all, or bond just slightly. This proposal contradicts the usual way the supports are planned.

Re: i3Mk2 - PLA warping on top of support - mid print not bed

Another way I plan to test one day (probably a software change would be needed) is to deliberately hard anchor the island to the support. This means here will be scar on the object, but the anchor should keep the overhang down. Usually at least with PLA one tries to avoid the scars by dropping the threads of filament lightly over the support so they do not bond at all, or bond just slightly. This proposal contradicts the usual way the supports are planned.

I think adaptive speed would already help a lot, if for example slic3r could be made to recognize overhangs, and reduce printing speed at those.

another weird thing I noticed pinting the "snakez" model from thingiverse, is that it happens more on the back and right of the printer, less at the font and left. not exclusively, but visibly more. which is weird, because I have another model, where it happens on all sides equaly.

Re: i3Mk2 - PLA warping on top of support - mid print not bed

> I think adaptive speed would already help a lot, if for example slic3r could be made to recognize overhangs, and reduce printing speed at those.

I wonder why is that. Maybe the slowly moving print head has time enough to discipline the overhang - it irons it down. Or maybe it is because the threads of plastic need a bit of time to stretch in mid air?

> another weird thing I noticed pinting the "snakez" model from thingiverse, is that it happens more on the back and right of the printer, less at the font and left. not exclusively, but visibly more. which is weird, because I have another model, where it happens on all sides equaly.

I believe this is due to the fan blowing from a single direction only. Usually the PLA prints look slightly better at the front where the fan is blowing.

Re: i3Mk2 - PLA warping on top of support - mid print not bed

> I think adaptive speed would already help a lot, if for example slic3r could be made to recognize overhangs, and reduce printing speed at those.

I wonder why is that. Maybe the slowly moving print head has time enough to discipline the overhang - it irons it down. Or maybe it is because the threads of plastic need a bit of time to stretch in mid air?

> another weird thing I noticed pinting the "snakez" model from thingiverse, is that it happens more on the back and right of the printer, less at the font and left. not exclusively, but visibly more. which is weird, because I have another model, where it happens on all sides equaly.

I believe this is due to the fan blowing from a single direction only. Usually the PLA prints look slightly better at the front where the fan is blowing.

I would love to find out. Its clearly not only a speed issue, because as you note , the fan also plays a role. The "ironing" effect could be what helps when you print slower, but I am wondering what makes the plastic warp up in the first place. should it not sag? why doesn't it?
Why always up and not down?
Maybe it has to do with z-hop? adhesion lifting the fresh overhang?

if you are interested to have a test-model for this, try http://www.thingiverse.com/thing:1709106

Re: i3Mk2 - PLA warping on top of support - mid print not bed

The curling up has to do with the die swell effect, uneven cooling and the fact that the plastic is held at the bottom surface only.
https://en.wikipedia.org/wiki/Die_swell

So the plastic thread wants to shrink back into its original diameter and because its bottom is held, it curls up in a similar fashion to a bimetal.

Re: i3Mk2 - PLA warping on top of support - mid print not bed

The curling up has to do with the die swell effect, uneven cooling and the fact that the plastic is held at the bottom surface only.
https://en.wikipedia.org/wiki/Die_swell

So the plastic thread wants to shrink back into its original diameter and because its bottom is held, it curls up in a similar fashion to a bimetal.

Ohh! Thank you!
Missing puzzle piece.

So, the curling starts at the previous level, which curls up, then doesnt have enough time to cool down and harden before the next layer is added which compounds the curling by the top layer wanting to conrtact and can do so on top and also (lightly less) on the bottom because the bottom one wants to go back to its previous (wrong) shape due not being cool enough yet.

\o/

cooling helps because the lower level will harden in the "correct" shape.
slower printing will help, because it improves cooling, or rather gives the part more time to take advantage of inadequate cooling.

Re: i3Mk2 - PLA warping on top of support - mid print not bed

This may be of interest to you.
https://ultimaker.com/en/community/5094-raised-edges

Re: i3Mk2 - PLA warping on top of support - mid print not bed

This may be of interest to you.
https://ultimaker.com/en/community/5094-raised-edges

Thank you! Thats a very interesting thread.

Re: i3Mk2 - PLA warping on top of support - mid print not bed

I had a part that did the curling edges thing and it always eventually caught the print head and broke. I tried some different settings in Slic3r and the problem remained. But I did finally find a solution that worked well: Load your 3d part into Meshmixer, and use Meshmixer to add the support. The supports from Meshmixer are actually attached to the part, so curling is greatly reduced. Since the pieces are attached better they don't move even if some curling occurs and the print head is pushing on them. The end result was a print that looked much cleaner on the back, even accounting for the support scars from the attached supports.

Meshmixer also lets you add and remove support manually, which can be very helpful with some troublesome parts. If you setup a new printer in Meshmixer with the Prusa i3 specs and point it to Slic3r as the printer program, you can just hit print in Meshmixer and it will send your part to Slic3r. This workflow has rescued the quality of my supported parts. Meshmixer is also perfect for modifying parts, and it has tools that make things like increasing the thickness of an area or smoothing out details very easy.

Use Meshmixer to add your supports and turn off supports in Slic3r.