G code for Annealing PLA on bed
Hello, I recently tried to anneal PLA in an oven and the mechanical and thermal properties of the PLA increased substantially.
I tried annealing thin PLA prints on the bed manually(adjusting bed temp by hand periodically) and got similar results. (MK3)
So I wonder if is it possible to write a G code especially for annealing PLA. Like as an end of G code attachment or as a separate file.
What the G code does is this: Heats the bed to 80C for 25min, and decrease temp 5 degree every 5min until 30C.
I am not too familiar with G code, just wondering if it is possible.
If it is, what are the commands for these actions?
Thanks!
Re: G code for Annealing PLA on bed
You'd need to adjust the M140 & M190 S values to what ever temperatures you want to anneal. If i'm not lazy I might venture to make a C applet that generates the code for you based on the starting temp, amount of temp drop, and duration to hold.
M140 = Set bed temp (S = temp in centigrade)
M190 = Wait on doing anything code wise until the temp reaches this value (S = temp in centigrade)
G4 = Wait this long before doing anything code wise (S = seconds, P = milliseconds)
M300 = Play a beep (S = frequency in hertz, P = duration in milliseconds)
M140 S80
M190 S80
G4 S1500
M140 S75
M190 S75
G4 S300
M140 S70
M190 S70
G4 S300
M140 S65
M190 S65
G4 S300
M140 S60
M190 S60
G4 S300
M140 S55
M190 S55
G4 S300
M140 S50
M190 S50
G4 S300
M140 0
M300 S300 P1000
The above example would have the bed heat up to 80 c, once the bed has been stable at 80 c, holds the temp for 25 minutes, lowers by 5 c, waits for stable temp, holds for 5 minutes, rinse repeat till the bed reaches 50 c. After holding a stable 50c for 5 minutes the bed turns off and the printer signals the end of the annealing process with a 1 second beep. From here you wait for the bed to cool to ambient as normal.
If you're using Slic3r PE you can put this in your Printer Settings > Custom G-code > End G-code section.
G4 ; wait
M221 S100
M104 S0 ; turn off temperature
M107 ; turn off fan
{if layer_z < max_print_height}G1 Z{z_offset+min(layer_z+30, max_print_height)}{endif} ; Move print head up
G1 X0 Y200; home X axis
M84 ; disable motors
M140 S80 ; start Annealing
M190 S80
G4 S1500
M140 S75
M190 S75
G4 S300
M140 S70
M190 S70
G4 S300
M140 S65
M190 S65
G4 S300
M140 S60
M190 S60
G4 S300
M140 S55
M190 S55
G4 S300
M140 S50
M190 S50
G4 S300
M140 0
M300 S300 P1000 ; signal end of Annealing
My suggestion would be to save the updated Printer settings under a new name (PLA Annealing).
Re: G code for Annealing PLA on bed
So I wonder if is it possible to write a G code especially for annealing PLA
You might have problems trying to use 80 on the bed since the temp is so concentrated and so much higher than the glass temp. You should only need to go to that temperature or just below.
I have much better results using lower temperatures for longer periods on time with the bed covered to get more even heating. Also, M86 resets the safety timer if you ever want to try longer intervals. It *will* time out during a dwell or wait if no other commands are executing
RE: G code for Annealing PLA on bed
I'm a bit late to this party, but are you actually using this technique? If so, how do you "cover the bed"?
I have a simple unheated WhamBam HotBox enclosure -- is that enough or would you suggest covering the print with some sort of box at the start of the annealing process?