Dual extruder - Preheat nozzle before tool change

sebkritikel

@modl Cura handles this pretty well, though I can’t remember if you need to install the ‘Machine Settings’ plugin or not (easy to install, can get it directly from the built in Cura add-in ‘store’).

Cura allows you to set standby temperatures, and in the Machine Settings section you can configure heat up and cool down rates for your tools. The generated gcode file has temperature commands embedded that aid in bringing the temperature up to temperature before the tool is selected in RRF.

modl

@sebkritikel Thank you very much for the info I'll give it a try too. Last time I used Cura (maybe one year ago?) it also had issues handling the large files I'm dealing with. Will report !

modl

@sebkritikel so Cura fails to slice my model, I'll leave that aside for now

@droftarts As for Prusaslicer's script i'm having trouble getting it to function . It is my understanding that it is looking for every M109 commands in the gcode to replace them with other commands a bit before the tool change. I tried editing my tool change gcode so it includes an M109 instead of the M116 I had set, but it still doesn't work. I need to dig

; tool change gcode 
G91
G1 Z1
G90
T[next_extruder]; select tool
M104 S160 T[previous_extruder] ; set previous extruder to standby temp
M109 S[temperature]  ; wait for temperature

Edit : Maybe i need M73s in the gcode too?

modl

I found the setting to add M73 commands but it still would not output the preheating commands, I'll try contacting the creator of the script, see if he is willing to share his config file

sebkritikel

@modl Re:Cura, do you believe it’s a file size issue? Just curious, as I exclusively use Cura, and the only slicing failures I’ve had deal with extremely large flat overhangs in conjunction with tree supports.

modl

@sebkritikel I don't have large flat overhangs, but i do have a lot of complex overhangs (printing a "realistic" model of a plant) using, indeed, tree supports.

sebkritikel

@modl ah gotcha, bummer to hear!

Not that you should be troubleshooting Cura, but if you’re so inclined - https://github.com/Ultimaker/Cura/discussions/18080

modl

@sebkritikel Thank you I tried with the nightly build. Still not able to slice but if i understand correctly, a report was sent to cura devs ? Hopefully this helps

sebkritikel

@modl Hope so!

Depending on how sensitive you are to sharing your print file, I could take a look at the project and see whats going on.

Insert the model into Cura, do File->Save Project, and then upload that .3mf file to Google drive (or an equivalent). You could post that link here, or directly message me the drive link,

modl

Hi eveyone here is an update on this. So I'm stil lnot able to have Prusa's macro to work, in the meantime I did two things , one is working the second remains to be tested. I needed to implement the first solution in deamon.g to accomodate an ongoing long print (2weeks) that didn't have a single macro called on tool changes.

This assumes that succesive layer times have little variations (successive tool work times are approximately similar) which is the case for me with variations from layer to layer being a couple tens of seceonds at max . The thing is, every tool is going to be preheated regardless of their future usage, which is OK in my case as both tools are used until the last layers

Here is what i have in deamon.g

if state.status == "processing"
	if exists(global.previousTool)    
		if state.currentTool != global.previousTool            ; executes right after tool change
			G10 P{abs(state.currentTool - 1)} R160
			if exists(global.newToolchangeTime)                ; intitialize previous tool change time with last know tool change time
				if !exists(global.previousToolchangeTime)
					global previousToolchangeTime = global.newToolchangeTime
				else
					set global.previousToolchangeTime = global.newToolchangeTime
			if !exists(global.newToolchangeTime)               ; update tool change time
				global newToolchangeTime = state.time
			else
				set global.newToolchangeTime = state.time
			echo "Last Toolchange time was :", global.previousToolchangeTime                 ; see if it works as intended
			echo "New Toolchange time is :", global.newToolchangeTime
			if exists(global.newToolchangeTime) && exists(global.previousToolchangeTime)
				echo "Calculating time between last tool changes..."
				if state.currentTool == 0	
					if !exists(global.lasttoolworkduration0)
						global lasttoolworkduration1 = global.newToolchangeTime - global.previousToolchangeTime
					else
						set global.lasttoolworkduration1 = global.newToolchangeTime - global.previousToolchangeTime
				if state.currentTool == 1	
					if !exists(global.lasttoolworkduration1)
						global lasttoolworkduration0 = global.newToolchangeTime - global.previousToolchangeTime
					else
						set global.lasttoolworkduration0 = global.newToolchangeTime - global.previousToolchangeTime
			if exists(global.lasttoolworkduration0)
				echo "It took", global.lasttoolworkduration1, "s between two tool changes from 1 to 0"
			else
				echo "Not enough tool changes were sampled"	
			if exists(global.lasttoolworkduration1)
				echo "It took", global.lasttoolworkduration0, "s between two tool changes from 0 to 1"
			else
				echo "Not enough tool changes were sampled"	
	if !exists(global.previousTool)
		global previousTool = state.currentTool
	else 
		set global.previousTool = state.currentTool
	
	if !exists(global.preheatingoffset)
		global preheatingoffset = 40
	else
		set global.preheatingoffset = 40           ; start heating up 60 seconds before next layer
	if exists(global.previousLayerTime) && exists(global.lasttoolworkduration0) && exists(global.lasttoolworkduration1)
		if state.currentTool == 1 && state.time >= global.newToolchangeTime + global.lasttoolworkduration1 - global.preheatingoffset
			echo "Preheating extruder ", abs(state.currentTool - 1), "..."
			G10 P{abs(state.currentTool - 1)} R{heat.heaters[abs(state.currentTool -1) + 1].active}
			;G10 P{state.currentTool} R150 
		elif state.currentTool == 0 && state.time >= global.newToolchangeTime + global.lasttoolworkduration0 - global.preheatingoffset
			echo "Preheating extruder ", abs(state.currentTool - 1), "..."
			G10 P{abs(state.currentTool - 1)} R{heat.heaters[abs(state.currentTool -1) + 1].active}
			;G10 P{state.currentTool} R150

Now the goal, and second solution will be to execute a macro called preheatextruders.g in prusaslicer tool change custom gcode that will handle the Time globals
and let deamon.g do the regular checks

It's DIY and has a rather narrow scope i know but I hope it can help others in similar situations

dc42

@modl thanks for sharing that.

In the future I have it in mind to be able to use the second file reader to run a simulation of the print in parallel with but ahead of the actual print. The simulation would be able to warn about upcoming tool changes, allowing for automatic tool preheat.