<p>That depends on the use. If you have a slate of glass a dip might be better (but the heat transfer at the dip would not be ideal), a bulge would stress and tilt the glass.</p>

<p>If you print directly onto the metal build surface it would not matter if you use a(n automatic) bed levelling system because you can compensate for the bulge or the dip using a mesh of the bed. Without a scan of the build platform you would have issues in getting the filament to stick.</p>

<p>Basically, there is not a better solution, best solution is to get a flat bed if the bulge or dip are making printing difficult.</p>

CC BY-SA 4.0
2019-11-23T07:28:26.097Z
Unfortunately I cannot ask them to check the bed with a straight edge before they ship it. I can just keep ordering them and returning them until I get one that is close to flat.
cds333
CC BY-SA 4.0
2019-11-23T10:51:38.093Z
@cds333 You need to address in your question how you use the bed. If you have glass on it you can go for a thin bed that easily adjusts to a thick, e.g. 4 mm slate of glass.
0scar
CC BY-SA 4.0
2019-11-22T06:58:23.157Z
2019-11-22T06:58:23.157Z
0scar
<p>Theoretically what is better- a warped bed with a dip in the middle, or a bulge in the middle?</p>

<p>(I would instinctively think that a dip would be better, since in a perfect world the glass build surface would still span the dip, and then the flatness of the surface relies on the structural integrity of the glass, whereas a bulge would not do the same, instead causing the glass to teeter atop the bulge)</p>

<p>Thoughts?</p>

CC BY-SA 4.0
2019-11-22T13:33:19.197Z
Which is better:  lose a leg to frostbite or lose a leg to fire?
Carl Witthoft
CC BY-SA 4.0
2019-11-23T07:16:55.080Z
@CarlWitthoft frostbite definitely! It happens all the time with mountain climbers. They can fit a prosthetic and still live a semi-normal life. Losing a leg to fire would result in horrible third degree burns to the torso and possibly face, lungs, eyes etc. Not sure what this has to do with 3d printing however...
cds333
CC BY-SA 4.0
2019-11-23T21:32:21.360Z
If you're going to sand it flat, there will be less material to remove, and so be easier, with a bulge in the middle. Is it warped only when heated or only when not heated?
Andrew Morton
<heated-bed><warping>
Warped bed - bulge vs dip?
cds333
# Warped bed - bulge vs dip?

(Asked by: username_0 on 2019-11-22)

Theoretically what is better- a warped bed with a dip in the middle, or a bulge in the middle?

(I would instinctively think that a dip would be better, since in a perfect world the glass build surface would still span the dip, and then the flatness of the surface relies on the structural integrity of the glass, whereas a bulge would not do the same, instead causing the glass to teeter atop the bulge)

Thoughts?

**Tags:** heated-bed, warping
> **Comments:**
> **username_1**: Which is better:  lose a leg to frostbite or lose a leg to fire?  
> **username_0**: @CarlWitthoft frostbite definitely! It happens all the time with mountain climbers. They can fit a prosthetic and still live a semi-normal life. Losing a leg to fire would result in horrible third degree burns to the torso and possibly face, lungs, eyes etc. Not sure what this has to do with 3d printing however...  
> **username_2**: If you're going to sand it flat, there will be less material to remove, and so be easier, with a bulge in the middle. Is it warped only when heated or only when not heated?  

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## 1 answers

### Answer by username_3 on 2019-11-22. Score: 2

That depends on the use. If you have a slate of glass a dip might be better (but the heat transfer at the dip would not be ideal), a bulge would stress and tilt the glass.

If you print directly onto the metal build surface it would not matter if you use a(n automatic) bed levelling system because you can compensate for the bulge or the dip using a mesh of the bed. Without a scan of the build platform you would have issues in getting the filament to stick.

Basically, there is not a better solution, best solution is to get a flat bed if the bulge or dip are making printing difficult.

> **Comments:**
> **username_0**: Unfortunately I cannot ask them to check the bed with a straight edge before they ship it. I can just keep ordering them and returning them until I get one that is close to flat.  
> **username_3**: @cds333 You need to address in your question how you use the bed. If you have glass on it you can go for a thin bed that easily adjusts to a thick, e.g. 4 mm slate of glass.  

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