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I've read different things about PLA and heat-bed. Some say it is not needed, others recommend 60-70°C, but not for the first layers.

For larger objects I often have the problem that the object does not stick to the blue-painters-tape-covered aluminium print plate. Instead the print "curls" up on one or more corners. To reduce this effect, I'm using a brim between 5 and 10mm. Depending on the size of the object the brim works quite well. Will heating the bed also improve the print quality by reducing the amount of heat warping / curling?

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    $\begingroup$ What's your extrusion temperature? $\endgroup$ – tbm0115 Dec 14 '16 at 21:02
  • $\begingroup$ +1 - As this post made me look up the difference between Rafts, Skirts and Brims! $\endgroup$ – Greenonline Dec 19 '16 at 16:45
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    $\begingroup$ See my answer, I have problems with curling, A combination of tape, hairspray and lowering the 1st layer height helped me overcome this issue. Now I very rarely see curling. $\endgroup$ – Festivejelly Dec 20 '16 at 13:49
  • $\begingroup$ Please select to accept an answer from the answers below or alternatively post your own answer to reduce the Unanswered Questions list. There are a few that certainly qualify to be accepted as answer! $\endgroup$ – 0scar Jun 26 '18 at 8:10

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Heating the bed helps me, even with PLA. I print with a 60 °C bed. The bed is 3/8" 6061 alloy aluminum, sanded with 600 grit sandpaper, coated with Elmer's purple glue stick, and dried.

The brim will help. You might make the brim thicker than one layer (like 2-3 layers).

If you look at the bottom of your print, are there large gaps where the PLA doesn't touch the bed? If so, you could zero the head closer to the bed, or increase the flow for the first layer.

I haven't set up a cooling fan, although many praise the results. It is an experiment for a future day.

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  • $\begingroup$ Slic3r does not offer an option for the layers of the brim, only for the raft. $\endgroup$ – Thomas S. Dec 14 '16 at 20:52
  • $\begingroup$ It did when I used it 1-2 years ago. $\endgroup$ – StarWind0 Dec 14 '16 at 21:54
  • $\begingroup$ Well, the latest slic3r version 1.2.9 from summer 2015 only has a checkbox for the brim but a layer count input field for the raft - (manual.slic3r.org/expert-mode/skirt vs. manual.slic3r.org/expert-mode/support-material). Could it be that the word "brim" means something different in slic3r and other slicers? $\endgroup$ – Thomas S. Jan 6 '17 at 18:44
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I actually find it's not needed for PLA. I generally have it heated to 40 °C and use blue painters tape along with some hairspray (I prefer Tresemme as it smells gorgeous).

I've experimented with a glass bed, and Buildtak but I find blue painters tape is the key. I overlap the blue tape ends to the bed so it sticks, then spray the hairspray onto the tape. Also bed leveling is super important as are your print settings. What you want for the first layer is to have it essentially "pushing" into the bed. That way it gets good contact and wont curl up during the print, though it can be a challenge to get off later.

TL;DR for PLA you dont need a heated bed, its more about the surface and 1st layer height.

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  • $\begingroup$ On the rare occasions I print PLA, I set the bed to 40C - because it works well. $\endgroup$ – Davo Jan 10 '18 at 12:55
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It really depends on your formulation. 70 °C would be on the higher end. I think I do between 70 °C - 75 °C. Not any higher.

Add a glue from a glue stick to help with keeping it on the bed.

Use a raft to reduce the issue as well.

A fan is the number one thing you can do.

The last solution is to build a heat enclosure. They are not on every 3D printer because of patents blocking them. You can easily make your own.

Technically it is not 100 % needed, i.e. the MakerBot does not use it, but the guys at MakerBot have PLA down to a science.

Also I thought Kapton is not for PLA usually... see these MatterHackers articles:

From RepRap Wiki - Glossary:

Raft

A technique used to prevent warping. Parts are built on top of a 'raft' of disposable material instead of directly on the build surface. The raft is larger than the part and so has more adhesion. Rarely used with heated build surfaces. For the small area models, it is very useful to prevent warping via adding a raft for the model before slicing it. It can also help with with precision parts by removing the slight first few layer distortion caused by the heated bed.

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  • $\begingroup$ Why exactly raft should help? IIRC, raft is nothing different than some kind of support. $\endgroup$ – Thomas S. Dec 14 '16 at 20:51
  • $\begingroup$ Well a raft is not really a support. It is to help with heat warping. See updated answer $\endgroup$ – StarWind0 Dec 14 '16 at 21:53
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Heated beds can help, but you have to be careful using too much heat. If you go above the glass transition temperature (about 60 °C for PLA), the stresses of the upper layers cooling will warp the bottom, because above the glass transition temperature, the PLA can deform.

For example, I was making very tall and skinny parts, a recipe for warping. At 65 °C, I had a bit of the bottom corners curling, but the part finished. I turned the heat up to 80 °C, and the parts warped so much they came off the build plate. I ran the exact same parts at 58 °C, and they came out beautifully every time.

A higher bed temperature can aid adhesion, (see Effect of the printing bed temperature on the adhesion of parts produced by fused filament fabrication), but if the temperature is above the glass transition, the parts can and will deform much more easily.

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    $\begingroup$ A nice answer and the link looks interesting too. However, if the link dies (as is the way of the internet) then maybe some useful information may be lost. It might be worth quoting relevant parts (no the whole thing though) of the article here. $\endgroup$ – Greenonline Jun 26 '18 at 7:13
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This is fundamentally a heat transfer problem. As a large print is being made, it is very thin. Thin things cool off quickly, especially when no new hot material is being placed on top in the meantime. A heated bed will only help for a time, depending on the print size, before it starts to actually contribute to warping due to rapidly cooling upper layers and still- heated lower layers.

A hack can be found by improving bed adhesion, but this leaves the underlying problem of thermal stresses intact. Only through better 3D printing thermal properties design or through better object design will the warping problem be solved rather than mitigated.

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For printing PLA you can manage to succeed without a heated bed. You can use blue painting tape on any platform. It will help a lot. But sometimes the tape itself curls up and you end up with a bad print. Heated bed helps here for better adhesion of the blue tape to the bed. You can also use hair sprey to ensure that the blue tape sticks to the bed.

Hair sprey is pretty effective on ABS. If you use a heated bed + glass + hair sprey ( Akat Gardi is the best brand) you will never have any problem with your prints.

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I can only go with my own experiences; a Printrbot simple metal originally with no heated bed and blue tape was fine for small parts if printed with a reasonable brim and rafts when needed (Slic3r does that) but larger prints tended to warp and curl. I upgraded to a heated bed, which I run at 55 - 60 °C for every print. Additionally, I now use Kapton tape on the bed and glue stick. I have recently reprinted a part for my printer, an LCD housing, to replace the badly warped original, which is my benchmark print. I have no warping/curling problems to the point that I have reduced the standard brim from 5 mm to 2 mm to save some material. Some additional detail - only PLA at present from a 0.4 mm extruder at 205 °C in 0.2 or 0.3 mm layer height for the finer detail. Takes longer but the results are worth it.

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The answer depends a bit on the type of PLA (supplier of specific filament), type of machine, type of build platform, size of model and ambient temperature.

PLA has less issues with warping compared to ABS or Nylon, but can still warp depending on everything mentioned. My usual first try to minimize warping is to heat the bed. 60 - 70 °C works well but I'll also go up to 100 depending on a variety of factors. If still not having any luck, generally on larger parts I try adding a raft. If I STILL have issues after that I'll add 'helper disks' (small quarter dollar sized disks) around the part to increase the surface area of the raft. The disks will add more material but I have about a 99 % success rate using these.

If a part is going to take more than about 3 hours and I can't have any warping at all, I always use a heated build plate and place the discs all the way around the part. Generally will add about a hour or more, but well worth the extra time.

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  • $\begingroup$ Do you mean brim (as option in the slicer, manual.slic3r.org/expert-mode/skirt) as "helper disks" or do you design them directly in the CAD? $\endgroup$ – Thomas S. Jan 6 '17 at 7:07
  • $\begingroup$ I'm a little unfamiliar with slic3r but my understanding of 'brim' is essentially the same as a 'raft'. A helper disk is an additional part that you add to the build link. If you're using a raft ( or brim) adding them around the edge or side that peels effectively extends the raft in that area. If you're printing directly onto the build plate, then you can place them under your part giving it a 'localized raft' removing it afterwards becomes more of a chore though. $\endgroup$ – Diesel Jan 6 '17 at 17:37
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A lot depends on exactly which PLA you use and the build surface. I'm using one of those new-fangled high-temperature PLA's (MakerGeek's Raptor PLA, black) and a BuildTac surface on a MonoPrice Select Mini v2. From my experiments, I believe that the biggest influence in preventing warping is the BuildTac.

My slicer is Simplify3d, so the settings may be in a different format than yours. I use a hot-end temperature of 240 °C, a bed temperature of 40 °C, layer height of 0.0875 mm, a first-layer modifier of 1.5, an extrusion modifier of 0.95, and a retraction distance of 3 mm.

I've never had a problem with warping, but these settings prevent stringing and allow me to more easily remove parts after printing. And yes, I wait until the bed gets to room temperature before removing the part.

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Heated bed definitely helps with PLA adhesion, it also helps depending the surface, for example PEI offers better adhesion than glass. Another option is to try to overextrude the first layer (125 %) and make sure it is squeezed out, so basically you get a wavy effect on the first layer. This should help a bit even in the curly corners. Another thing I have noticed from experience is the PLA itself, not all PLAs are the same so you could try another manufacturer or try your PLA in a friend's printer to see if you get the same effect. Generally on PLA we do not expect any warping, but the reality is that some do have.

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Heating the bed helps with adhesion to the bed, but can seriously interfere with cooling of the layers just above the bed that are in contact with large amounts of material touching the bed. I've found that, if I have a model with a flat region touching the bed and walls leaning outward from it (overhangs) as they go up, any corners will curl upwards before they can cool if the bed is 60 °C or above - it's effectively a heat bath at the glass transition temperature that's going to be hard for a fan to overcome.

At 50 °C the effect is almost gone, and at 40 °C and below it seems entirely gone, but the exact temperature that's safe is going to depend on ambient room temperature, cooling fan power, and effectiveness of the fan duct. I've just found this as a solution to my curling-corner problems, so I might end up tweaking things more, but I think I'm going to try printing PLA without heating the bed at all unless I have trouble with adhesion.

An example showing slightly warped vertex/edge from curling corners at 50 °C vs good ones at lower temperatures:

3 icosahedrons printed at unheated, 40, and 50 °C

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