Notifications
Clear all

Temperature changes between print/calibration/idle  

  RSS
YigalB
(@yigalb)
Eminent Member
Temperature changes between print/calibration/idle

Is it possible, in order to do things faster:

1- Make the probing and printing at same temperature (215)? It is annoying when the temp needs to drop from 215 to 170 for calibration, and then go up again for printing. 

2- keep the temp high (215) after print is finished instead of cooling down? (perhaps for a period like 10 minutes or so).

Posted : 18/05/2021 2:55 pm
Neophyl
(@neophyl)
Famed Member
RE: Temperature changes between print/calibration/idle

Yes it is.

You can simply edit the start  and end gcode found under the printer definition in Prusa Slicer and then save the modified profile as a new one (as you cant edit default profiles).  Then you select your 'new' printer when slicing and the changed commands will be used on those prints.

However before doing so please be aware that the current commands are there for a reason.  For example the probing is done at 170 to stop the nozzle dripping molten plastic onto the print surface when it probes.  Originally the probing was done at full temp but user feedback about the annoying plastic deposited on the bed drove the change to what is used now.
Similarly turning the heaters off after a print is done for safety reasons.  However if you want to edit then its up to you, its your printer.  

Editing the gcode start/end is an 'expert' level setting in PS.  If you don't know what you are doing then please beware as you can potentially screw things up.  

Posted : 18/05/2021 4:21 pm
--
 --
(@)
Illustrious Member
RE: Temperature changes between print/calibration/idle

Conceivably you could edit the the gcode to have the printer start heating the bed and nozzle, do a home, then start printing. That would cut down on all that preheat time. You might not get 100% of the first layer, but the print would finish faster. You can also increase the print speeds via gcode. Turn it up to 200% and the printer will print as fast as it can most of the time, making use of the 200 mm/s spec the MK3 has. 

I'd never do those things, but if you are really in a hurry...

Posted : 18/05/2021 5:00 pm
YigalB
(@yigalb)
Eminent Member
Topic starter answered:
RE: Temperature changes between print/calibration/idle

Sorry guys, I meant something else. I don't want to change the run time, I just want to save sometime before the print starts.

Sometimes the Mini printer spend sometime lowering the temp when it starts probing (from 215 to 170), and then heats it up again. So I wonder why to lower the temp is the probing temp-dependent?  Does it have to be at 170?

Also, when print ends, the printer is cooling down automatically. I would like to keep it hot for 10-15 minutes, since I am often starting another print. 

Is there a way to set a different profile at the printer level? (not in the gcode)

Posted : 19/05/2021 7:33 am
Neophyl
(@neophyl)
Famed Member
RE: Temperature changes between print/calibration/idle

@yigalb

No you cant set anything on the printer.  You have to modify the start and end gcode to do what you want.  A lot of the existing 'operation' of your printer is not actually in the printers firmware but is contained in the settings in PS.

For example the End gcode block from the Printer profile is added to the end of the output file when sliced, that contains the commands to turn off the extruder and bed heater and also commands that do the move the print bed to the front etc, move the print head up etc.

You could simply remove the commands that turn the heaters off.  They would then stay on.  At least until the printers firmware safety timer kicks in and turns them off.  Which is about 30 minutes iirc.  The problem with that is you are relying on the printers firmware to provide a safety critical operation.  While it **should** be OK, do you really want to bet your life on it working flawlessly every time ?

You could edit the end code to move the print bed to the front and then wait 10 minutes and then do the cooldown with the appropriate Dwell  command added in.  Although offhand I'm not sure what the max limit for Dwell is.  It also depends on if the Mini firmware's gcode parser supports the G4 Dwell command.

On the startup routine its always assumed you are printing from a cold start and 170 degrees was chosen by prusa as a suitable temp as its low enough to not cause filament oozing but high enough for it to be soft so its wont damage the bed while probing.  While you could do probing at 210 or whatever that WILL leave little spots of plastic at the probe points which will ruin your prints first layers.  Yes its a bit of time for it to cool down to 170 between prints but thats far better than having ruined prints from plastic deposits.  

As I said its your printer and you can adjust it to work however you want.  As long as you know how to do it with gcode.  If you don't know enough to do that then you really shouldn't be messing with it in the first place.  Not until you have educated yourself on the pro's and con's and all the implications on what you want to do.  Once you have done that you wont need to ask is xxx possible, you will know what is and isnt and can make informed choices.
As a start you can read though the list of (potential) gcode commands at  https://marlinfw.org/meta/gcode/

including the Dwell command  https://marlinfw.org/docs/gcode/G004.html

 

Posted : 19/05/2021 8:03 am
YigalB liked
--
 --
(@)
Illustrious Member
RE: Temperature changes between print/calibration/idle

@yigalb

And something to think about: you are printing something that will take hours. Why worry about a few seconds? 

During all the pauses and delays that you are concerned about, the printer is doing some critical tasks that affect print quality. Waiting for temps to stabilize before measuring bed irregularities being one of them. As Neophyl mentioned earlier, it does some tasks at lower temperatures to help you maintain a clean print sheet - filament oozes when kept at temp too long. Search for the term 'gnats' on the forum for all the people who have been affected by this problem the stepped warmup fixes. It drools down and leaves drops or even strings on the platter that will get caught up in your print and make a mess, or even cause stalls and shifts.

As for keeping everything hot. Hot plastic actually cooks. It is a bad idea to keep plastic hot in the nozzle and then just bake it. It can scorch and burn in the nozzle and leaves residues that are problems and can lead to clogs. That said - ditto on Neo's words. Learn gcode and make the printer do exactly what you want.

Also - Octoprint has features and control extensions you might like. 

 

Posted : 19/05/2021 8:22 am
YigalB liked
YigalB
(@yigalb)
Eminent Member
Topic starter answered:
RE: Temperature changes between print/calibration/idle
Posted by: @tim-2

@yigalb

And something to think about: you are printing something that will take hours. Why worry about a few seconds? 

 

True. However, I am trying to save my time, not the printer's time. The root problem in my case is that every 2-3 weeks the filament doesn't come out as it should, and then I got used to do cold pull, and afterwards release the 3 tiny screws on the print head and align the print head height up, close to the plastic tube. Then it works perfectly for 2-3 weeks again. Other than that, I have no issue with the waiting time. 

Posted : 19/05/2021 12:57 pm
Share: