# Hollow prints blowing out

**URL:** <https://forum.formlabs.com/t/hollow-prints-blowing-out/1131>\
**Category:** General Discussion\
**Created:** [May 22, 2014, 3:12am UTC](https://forum.formlabs.com/t/hollow-prints-blowing-out/1131 "2014-05-22T03:12:01Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![VinceErb](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/vinceerb/32/20_2.png) [@VinceErb](https://forum.formlabs.com/u/VinceErb)\
**Post date:** [May 22, 2014, 3:12am UTC](https://forum.formlabs.com/t/hollow-prints-blowing-out/1131/1 "2014-05-22T03:12:01Z")

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Every time a print a hollow model, if I don’t immediately drill a hole in it somewhere they blow out.

There is barely any resin trapped inside so it must have an expanding gas causing the blowouts.

![](https://support.formlabs.com/attachments/token/xWEGbNoXzlfDUzhFPNovBduZu/?name=IMG_20140521_224053.jpg)

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**Author:** ![DanielDavis](https://avatars.discourse-cdn.com/v4/letter/d/e9bcb4/32.png) [@DanielDavis](https://forum.formlabs.com/u/DanielDavis)\
**Post date:** [May 22, 2014, 4:16am UTC](https://forum.formlabs.com/t/hollow-prints-blowing-out/1131/2 "2014-05-22T04:16:21Z")

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I’ve had the same thing happen. During the peel, the suction at the model - PDMS interface is pulling in on your thin-walled hollow models disrupting their integrity. IMHO, the phenomenon is a function of the stereolithography process as applied by Formlabs. A slower peel with a softer PDMS layer might help. It remains to be seen whether or not Fromlabs will address these two issues.

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**Author:** ![VinceErb](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/vinceerb/32/20_2.png) [@VinceErb](https://forum.formlabs.com/u/VinceErb)\
**Post date:** [May 22, 2014, 5:00am UTC](https://forum.formlabs.com/t/hollow-prints-blowing-out/1131/3 "2014-05-22T05:00:13Z")

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No mine are fine coming out of the printer but bust open later.

If I hurry and drill a hole before it happens they are fine but I forget to alot.

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**Author:** ![DanielDavis](https://avatars.discourse-cdn.com/v4/letter/d/e9bcb4/32.png) [@DanielDavis](https://forum.formlabs.com/u/DanielDavis)\
**Post date:** [May 22, 2014, 5:22am UTC](https://forum.formlabs.com/t/hollow-prints-blowing-out/1131/4 "2014-05-22T05:22:09Z")

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Sorry, I get it now. I’m thinking that it’s gotta relate to the combined gas law, PV=Tk, somehow. If the inside air pressure increases after printing popping your models, either the air temperature is increasing or the model volume is shrinking, or both.

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**Author:** ![VinceErb](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/vinceerb/32/20_2.png) [@VinceErb](https://forum.formlabs.com/u/VinceErb)\
**Post date:** [May 22, 2014, 6:09am UTC](https://forum.formlabs.com/t/hollow-prints-blowing-out/1131/5 "2014-05-22T06:09:32Z")

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Yip! I think so, you wouldn’t think it would be enough to do it but it keeps on happening.

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**Author:** ![RichardAmidon](https://avatars.discourse-cdn.com/v4/letter/r/96bed5/32.png) [@RichardAmidon](https://forum.formlabs.com/u/RichardAmidon)\
**Post date:** [May 23, 2014, 2:04pm UTC](https://forum.formlabs.com/t/hollow-prints-blowing-out/1131/6 "2014-05-23T14:04:43Z")

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Hey Vince, I remember reading this in the Help Center modeling tips section that you should actually design models that are hollow with a small hole. It states to do this to allow resin to escape but as you said you don’t find any liquid resin trapped after you drill the hole in yours so I guess maybe it is from something else.

Anyway here is what I found, hope this helps.

[https://support.formlabs.com/entries/23384357-Design-Models-for-Printability](https://support.formlabs.com/entries/23384357-Design-Models-for-Printability)

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<div class="post-metadata">

**Author:** ![VinceErb](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/vinceerb/32/20_2.png) [@VinceErb](https://forum.formlabs.com/u/VinceErb)\
**Post date:** [May 23, 2014, 9:30pm UTC](https://forum.formlabs.com/t/hollow-prints-blowing-out/1131/7 "2014-05-23T21:30:44Z")

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Yeah that post was about so as to not trap resin, but that’s not the problem.

But if I knew how to add a hole into an STL file I would!

I guess I’m going to have to figure out how…