<p>&quot;Real overhang limits&quot; are hard to define. If you want <em>accurate extrusion</em>, such that precision parts fit together correctly or angled geometric surfaces that are supposed to be flat come out flat, each extrusion line must have at least some minimal portion of itself (probably including its center line) printed on top of and against existing material underneath that already has sufficient rigidity (both geometrically and in terms of cooling) not to deflect when printing against it. In this sense, the overhang angle is <code>arctan(lw * (1-k) / lh)</code> where <code>lh</code> is layer height, <code>lw</code> is line width (normally nozzle width), and <code>k</code> is the portion of overlap you demand. For example at 0.4 line width, 0.2 layer height, and 50% overlap, you get out exactly 45°.</p>
<p>If you just want the printed part to have basic structural integrity, things get a lot more fuzzy, and dependent on the geometry - particularly, the convexity/cocavity of any overhanging extrusions. Concave overhangs, like the inside of a spherical dome, will <em>quickly fail</em> as soon as you lose most or all of the overlap - expect them to hard-fail at <code>arctan(lw/lh)</code> (63° in 0.4/0.2 case) since the material will just be dragged inward around the curve with nothing to stick to. You might get a little bit more overhang if there's already a horizontally adjacent extrusion in the new layer for the material to stick to, but in my experience it will be unreliable.</p>
<p>Convex overhangs, on the other hand, can work out even when they're extreme. This is because the curvature of the toolhead path pulls the new material towards/against a region where it has existing material to bond to.</p>
<p>Keep in mind that layer height is a free parameter you can tune, that greatly increases the overhang available to you. Some slicers also have &quot;adaptive layer height&quot; settings to use thinner layers precisely in the layers that have severe overhangs. Line width is also a parameter you can tune, and increasing it works in your favor up to a point. But once you get to a point where the &quot;wider than nozzle&quot; line is attempted over thin air, it will fail badly, sagging down rather than expanding to the desired width, and not bonding to adjacent lines. So if you use wider lines to get better overhangs, you need to be very attentive not to go over angles that would place their centers off of the previous layer.</p>

CC BY-SA 4.0
2022-04-11T14:28:19.680Z
Thats a pretty good explanation, what would you call 'extreme'?
Kilisi
CC BY-SA 4.0
2022-04-11T14:33:54.107Z
@Kilisi: I don't have a figure in mind, but I know I've printed some solid parts, including cosmetic surface quality, with convex overhangs over 70°. If you slice to print walls from the innermost going outward, I can imagine that a convex overhang (with continuous curvature, not long straight segments) might work well even when only the innermost wall of the new layer sits on existing material from the previous layer, which could be up to something like 80° with 3 walls (and 0.4/0.2).
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-04-11T15:35:40.757Z
Makes sense. I don't really do complex parts. Good to know other people have done steeper overhangs. Why does everyone talk about parts, I can't see a market for them, anything I print would be cheaper and faster to buy.
Kilisi
CC BY-SA 4.0
2022-04-11T19:01:51.193Z
@Kilisi: "Part" is kinda just the generic term a lot of folks use for "printed object", but there's so much you can print that is a "part" in the sense of filling some mechanical/structural role that would be prohibitively difficult to obtain in any other way short of just buying a complete replacement for whatever needs it. This includes things like door closer brackets (one I did recently), gears, specialized tubing couplers/adapters, electronics enclosures, and of course components for more 3D printers, CNC machines, or other tools/machinery used for making things.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-04-12T02:08:52.760Z
I get that some parts are hard to obtain, but I'm an engineer I could fabricate a structural part out of wood, metal, plastic or something else faster and stronger than anything I could 3d print.
Kilisi
CC BY-SA 4.0
2022-04-12T12:55:30.127Z
"why would anyone buy 3d printed parts" sounds like a good question to ask separately.
user10489
CC BY-SA 4.0
2022-04-13T04:23:54.150Z
@user10489: The question suggested in the comments here didn't seem to be about *buying* 3d printed parts, just questioning the very concept of making them. If you'd like to take a stab at asking this question in a form that's within the scope of the site, not too opinion-based, etc. I'd be happy to take a stab at answering it.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-04-16T01:06:20.553Z
@R..GitHubSTOPHELPINGICE great, I asked it in a separate question, interested in your take on the matter, you seem to have a good logical grasp of things.
Kilisi
CC BY-SA 4.0
2022-04-16T01:07:41.040Z
@user10489 the question was asked, feel free to give your thoughts on the matter
Kilisi
CC BY-SA 4.0
2022-04-11T14:25:15.100Z
2022-04-11T14:37:08.687Z
2022-04-11T14:37:08.687Z
R.. GitHub STOP HELPING ICE
<p>It is very difficult to determine a definitive number/value for the overhang angle, this is very dependent on the temperature, speed, material, nr. of walls amount of cooling fan percentage and the effectivity of the fan duct and your object geometry. Probably more settings are applicable.</p>
<p>You could find out what the specific values for you printer and your settings are by printing an overhang test, e.g. like <a href="https://www.thingiverse.com/thing:2656594" rel="nofollow noreferrer">this one</a>:</p>
<p><a href="https://i.sstatic.net/Xcypr.png" rel="nofollow noreferrer" title="All In One 3D Printer test"><img src="https://i.sstatic.net/Xcypr.png" alt="All In One 3D Printer test" title="All In One 3D Printer test" /></a></p>
<p>Such a test will give you definitive answers on the overhang angle for your specific slicer settings and machine capabilities.</p>

CC BY-SA 4.0
2022-04-11T10:48:56.647Z
2022-04-11T17:31:03.907Z
2022-04-11T17:31:03.907Z
0scar
<p>From my limited experience there is very little in the way of overhangs that won't print for a short distance. Depending what you're printing and what it's end use will be.</p>
<p>In this case it needs to be robust enough for daily use holding napkins and toothpicks and cutlery at a restaurant.</p>
<p>The model in the question printed for about 3 centimeters well over the threshold as shown in the picture and will print a bit more before joining the rest of the arm.</p>
<p>The overhang tests available online are in my opinion a waste of time. It would be very bad design to print something like them because if it's not joining anything it would be too fragile to be any use. Dropping it off a table accidently or breathing too hard near it might result in it snapping.</p>
<p>So if the distance is short anything up to about 80 - 85 % is possible. What happens is that the leading edge bends upwards a little bit after it prints. Then the next layer heats it soft and pushes it down and deposits on top of it (which then warps upwards) until it eventually reaches the join where the final warp is pushed down and joins nicely.</p>
<p>You can do all the fancy tests you want, but this is how it actually works in practice.</p>
<p>I find that post processing afterwards is minimal, less than if I'd used supports.
<a href="https://i.sstatic.net/rO8hB.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/rO8hB.jpg" alt="Overhang after 1 hour" /></a></p>

CC BY-SA 4.0
2022-04-11T11:44:54.497Z
2022-04-11T12:16:55.440Z
2022-04-11T12:16:55.440Z
Kilisi
<p>What are the real overhang limits? I see a lot online about 45 %, then up to 60 %, but I'm routinely doing them at up to 90 % for &quot;shortish&quot; distances and 80%+ for several centimeters at a time. I haven't tried to see how far I can do it, since I don't have filament to waste on that sort of thing.</p>
<p>It's making me wonder how believable all the YouTube and website experts are. Same thing with stringing, they all talk about it on Ender 3's but this print has been going for 25 hours and has maybe two tiny strings.</p>
<p>This is the second time I've printed this same STL with no supports.</p>
<ul>
<li>0.2 mm layer height</li>
<li>Ender 3 Pro</li>
<li>Generic PLA</li>
</ul>
<p><a href="https://i.sstatic.net/IqHWF.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/IqHWF.jpg" alt="Overhang" /></a></p>

<print-quality>
Practical overhang limits
Kilisi
# Practical overhang limits

(Asked by: username_0 on 2022-04-11)

What are the real overhang limits? I see a lot online about 45 %, then up to 60 %, but I'm routinely doing them at up to 90 % for "shortish" distances and 80%+ for several centimeters at a time. I haven't tried to see how far I can do it, since I don't have filament to waste on that sort of thing.

It's making me wonder how believable all the YouTube and website experts are. Same thing with stringing, they all talk about it on Ender 3's but this print has been going for 25 hours and has maybe two tiny strings.

This is the second time I've printed this same STL with no supports.

* 0.2 mm layer height
* Ender 3 Pro
* Generic PLA

[![Overhang](https://i.sstatic.net/IqHWF.jpg)](https://i.sstatic.net/IqHWF.jpg)

**Tags:** print-quality

---

## 3 answers

### Answer by username_1 on 2022-04-11. Score: 1 | Accepted answer

"Real overhang limits" are hard to define. If you want *accurate extrusion*, such that precision parts fit together correctly or angled geometric surfaces that are supposed to be flat come out flat, each extrusion line must have at least some minimal portion of itself (probably including its center line) printed on top of and against existing material underneath that already has sufficient rigidity (both geometrically and in terms of cooling) not to deflect when printing against it. In this sense, the overhang angle is `arctan(lw * (1-k) / lh)` where `lh` is layer height, `lw` is line width (normally nozzle width), and `k` is the portion of overlap you demand. For example at 0.4 line width, 0.2 layer height, and 50% overlap, you get out exactly 45°.

If you just want the printed part to have basic structural integrity, things get a lot more fuzzy, and dependent on the geometry - particularly, the convexity/cocavity of any overhanging extrusions. Concave overhangs, like the inside of a spherical dome, will *quickly fail* as soon as you lose most or all of the overlap - expect them to hard-fail at `arctan(lw/lh)` (63° in 0.4/0.2 case) since the material will just be dragged inward around the curve with nothing to stick to. You might get a little bit more overhang if there's already a horizontally adjacent extrusion in the new layer for the material to stick to, but in my experience it will be unreliable.

Convex overhangs, on the other hand, can work out even when they're extreme. This is because the curvature of the toolhead path pulls the new material towards/against a region where it has existing material to bond to.

Keep in mind that layer height is a free parameter you can tune, that greatly increases the overhang available to you. Some slicers also have "adaptive layer height" settings to use thinner layers precisely in the layers that have severe overhangs. Line width is also a parameter you can tune, and increasing it works in your favor up to a point. But once you get to a point where the "wider than nozzle" line is attempted over thin air, it will fail badly, sagging down rather than expanding to the desired width, and not bonding to adjacent lines. So if you use wider lines to get better overhangs, you need to be very attentive not to go over angles that would place their centers off of the previous layer.

> **Comments:**
> **username_0**: Thats a pretty good explanation, what would you call 'extreme'?  
> **username_1**: @Kilisi: I don't have a figure in mind, but I know I've printed some solid parts, including cosmetic surface quality, with convex overhangs over 70°. If you slice to print walls from the innermost going outward, I can imagine that a convex overhang (with continuous curvature, not long straight segments) might work well even when only the innermost wall of the new layer sits on existing material from the previous layer, which could be up to something like 80° with 3 walls (and 0.4/0.2).  
> **username_0**: Makes sense. I don't really do complex parts. Good to know other people have done steeper overhangs. Why does everyone talk about parts, I can't see a market for them, anything I print would be cheaper and faster to buy.  
> **username_1**: @Kilisi: "Part" is kinda just the generic term a lot of folks use for "printed object", but there's so much you can print that is a "part" in the sense of filling some mechanical/structural role that would be prohibitively difficult to obtain in any other way short of just buying a complete replacement for whatever needs it. This includes things like door closer brackets (one I did recently), gears, specialized tubing couplers/adapters, electronics enclosures, and of course components for more 3D printers, CNC machines, or other tools/machinery used for making things.  
> **username_0**: I get that some parts are hard to obtain, but I'm an engineer I could fabricate a structural part out of wood, metal, plastic or something else faster and stronger than anything I could 3d print.  
> **username_2**: "why would anyone buy 3d printed parts" sounds like a good question to ask separately.  
> **username_1**: @user10489: The question suggested in the comments here didn't seem to be about *buying* 3d printed parts, just questioning the very concept of making them. If you'd like to take a stab at asking this question in a form that's within the scope of the site, not too opinion-based, etc. I'd be happy to take a stab at answering it.  
> **username_0**: @R..GitHubSTOPHELPINGICE great, I asked it in a separate question, interested in your take on the matter, you seem to have a good logical grasp of things.  
> **username_0**: @user10489 the question was asked, feel free to give your thoughts on the matter  

---

### Answer by username_3 on 2022-04-11. Score: 3

It is very difficult to determine a definitive number/value for the overhang angle, this is very dependent on the temperature, speed, material, nr. of walls amount of cooling fan percentage and the effectivity of the fan duct and your object geometry. Probably more settings are applicable.

You could find out what the specific values for you printer and your settings are by printing an overhang test, e.g. like [this one](https://www.thingiverse.com/thing:2656594):

[![All In One 3D Printer test](https://i.sstatic.net/Xcypr.png "All In One 3D Printer test")](https://i.sstatic.net/Xcypr.png "All In One 3D Printer test")

Such a test will give you definitive answers on the overhang angle for your specific slicer settings and machine capabilities.


---

### Answer by username_0 on 2022-04-11. Score: -1

From my limited experience there is very little in the way of overhangs that won't print for a short distance. Depending what you're printing and what it's end use will be.

In this case it needs to be robust enough for daily use holding napkins and toothpicks and cutlery at a restaurant.

The model in the question printed for about 3 centimeters well over the threshold as shown in the picture and will print a bit more before joining the rest of the arm.

The overhang tests available online are in my opinion a waste of time. It would be very bad design to print something like them because if it's not joining anything it would be too fragile to be any use. Dropping it off a table accidently or breathing too hard near it might result in it snapping.

So if the distance is short anything up to about 80 - 85 % is possible. What happens is that the leading edge bends upwards a little bit after it prints. Then the next layer heats it soft and pushes it down and deposits on top of it (which then warps upwards) until it eventually reaches the join where the final warp is pushed down and joins nicely.

You can do all the fancy tests you want, but this is how it actually works in practice.

I find that post processing afterwards is minimal, less than if I'd used supports.
[![Overhang after 1 hour](https://i.sstatic.net/rO8hB.jpg)](https://i.sstatic.net/rO8hB.jpg)


---

