How to write a G-code to cool the heat bed by 5°C every 1 hour, so as to solve the problem of reducing shrinkage and deformation?

Snapmaker Artisan
1

Cause: I use PETG to print large workpieces (more than 300mm in length) and everything works fine during the printing process, no cracks and warping. However, after being removed, it shrinks and deforms due to cooling.

Idea: Maintaining the temperature inside the hood and cooling it down slowly is an effective way to solve the cold shrinkage deformation. I’d like to add a piece of G-code after printing to let the bed continue to heat up and lower the temperature every hour.

Logic:

  1. At the end of printing, get the current hot bed temperature.
  2. The target temperature of the hot bed is reduced by 5°C and maintained for 1 hour, and the target temperature is reduced by 5°C and maintained for 1 hour , and so on.
  3. If the target temperature of the hot bed is lower than the ambient temperature, it will end

Request:
I don’t know how to write G-code, so I hope you can help. Thank you so much.

2

I don’t see a real benefit by cooling down slower but hey, if it helps you it’s OK.

You need at least the ability to edit your gcodes or to post process.

Its simple to:

After the finished print you maybe could start a own gcode with:

M140 S60; heat the bed to 60degrees
G4 S3600; wait for 3600 sec, no interaction possible
M140 S50; heat the bed to 50 degrees
G4 S3600; wait again…
M140 S40
G4 S3600
M140 S30
G4 S3600
M140 S0; disable heated bed

If you need further information, feel free to ask :wink:

1 Like
3

How about just leaving to cool in situ instead of removing it?

4

Thank you so much

In my opinion, a slow cooling process can reduce the cold shrinkage deformation stress。

In particular, the deformation of the contact surface with the hot bed

Thanks again

5

Thanks for the concern. That’s what I did before that. After printing, do not take it off, close the door, and let it cool naturally for 10 hours.

Everything is normal during the printing process, there is no warping and detachment, and every edge is normal.

After printing, the workpiece is removed after 10 hours of standing, and the contact surface with the hot bed is gradually deformed, and the edge of 300mm is bent by about 0.5mm. The other edges remain normal.

I use PETG material