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Drafty room with grumpy occupants  

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r4z0r7o3
(@r4z0r7o3)
Member
Drafty room with grumpy occupants

My printer is unfortunately in a room without stable temperature control and occasional grumpy occupants who don't like loud vent fans disturbing their TV.  So I had an idea: What about adding some vent open/close commands to the "Between objects" or "Before/after layer change" custom g-code?

I don't know the g-code for "current temperature" but something like this is what I was thinking:

(if chamber_minimal_temperature[initial_tool] > current_temperature)
M870 O
(else)
M870 C
(endif)

Could this work, or are the conditional statements only evaluated when generating the g-code and not at runtime?

Posted : 16/12/2025 2:12 pm
hyiger
(@hyiger)
Noble Member
RE: Drafty room with grumpy occupants

 

Posted by: @r4z0r7o3

My printer is unfortunately in a room without stable temperature control and occasional grumpy occupants who don't like loud vent fans disturbing their TV.  So I had an idea: What about adding some vent open/close commands to the "Between objects" or "Before/after layer change" custom g-code?

I don't know the g-code for "current temperature" but something like this is what I was thinking:

(if chamber_minimal_temperature[initial_tool] > current_temperature)
M870 O
(else)
M870 C
(endif)

Could this work, or are the conditional statements only evaluated when generating the g-code and not at runtime?

I posted a reply in a similar thread: https://forum.prusa3d.com/forum/prusa-core-one-hardware-firmware-and-software-help/test-auto-vent-operation-with-petg-posing-as-abs/#post-774528

Posted : 16/12/2025 6:46 pm
Jürgen
(@jurgen-7)
Noble Member
RE: Drafty room with grumpy occupants

But how does it help with the fan noise?

Posted : 16/12/2025 7:31 pm
hyiger
(@hyiger)
Noble Member
RE:

 

Posted by: @jurgen-7

But how does it help with the fan noise?

I think he means with the top vent closed it's less noisy. But then if you are maintaining a certain chamber temp then the vent needs to be closed anyway...

I miss read it as an issue with vent open/close. 

This post was modified 2 hours ago by hyiger
Posted : 16/12/2025 8:20 pm
r4z0r7o3
(@r4z0r7o3)
Member
Topic starter answered:
RE: Drafty room with grumpy occupants
Posted by: @jurgen-7

But how does it help with the fan noise?

I was thinking more like the fans would run slower / work less hard drawing cooling air into the chamber with the vent open, lowering the temps.  And for the opposite, obviously the chamber would heat up slightly faster without the top vent open.

Posted : 16/12/2025 9:09 pm
r4z0r7o3
(@r4z0r7o3)
Member
Topic starter answered:
RE: Drafty room with grumpy occupants
Posted by: @hyiger

 

Posted by: @r4z0r7o3

My printer is unfortunately in a room without stable temperature control and occasional grumpy occupants who don't like loud vent fans disturbing their TV.  So I had an idea: What about adding some vent open/close commands to the "Between objects" or "Before/after layer change" custom g-code?

I don't know the g-code for "current temperature" but something like this is what I was thinking:

(if chamber_minimal_temperature[initial_tool] > current_temperature)
M870 O
(else)
M870 C
(endif)

Could this work, or are the conditional statements only evaluated when generating the g-code and not at runtime?

I posted a reply in a similar thread: https://forum.prusa3d.com/forum/prusa-core-one-hardware-firmware-and-software-help/test-auto-vent-operation-with-petg-posing-as-abs/#post-774528

Yeah! Thanks for that, I had already found it and am using it.  It was partially what inspired my question.

That said, I have a feeling the conditional-statements are only acted upon at g-code generation time, not runtime.  If nobody knows off-hand, I s'pose I could just take a peek at some generated g-code to check.

Posted : 16/12/2025 9:12 pm
hyiger
(@hyiger)
Noble Member
RE: Drafty room with grumpy occupants

 

Posted by: @r4z0r7o3

That said, I have a feeling the conditional-statements are only acted upon at g-code generation time, not runtime.  If nobody knows off-hand, I s'pose I could just take a peek at some generated g-code to check.

They are macros so it's compile time not run time

Posted : 16/12/2025 10:03 pm
Jürgen
(@jurgen-7)
Noble Member
RE: Drafty room with grumpy occupants

If the idea was to change the vent setting during the runtime of the print, maybe multiple times, as an alternative means for temperature regulation -- that won't work via the Gcode. But it would not be desirable anyway:

When printing PLA and PETG, the vents will need to be open throughout the print. Otherwise the chamber temperature will get too high, even with the fans running.

When printing filaments which require a high chamber temperature, the vents should remain closed. The fans won't run very hard, since the printer radiates a lot of heat anyway: Getting the temperature high enough is the bigger struggle typically. (By the way -- if you are printing these filaments, you should probably think about ventilation, filtering the exhaust air from the printer, or ducting it to the outside. You probably don't want to make those room occupants sick on top of grumpy...)  

Posted : 16/12/2025 10:17 pm
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