Pause at layer height

[SweHogelid]

@jlastofka
This is pretty much how I used to do it and to some extent still doing, havent heard the name ’witness’ though I thought more of it as a sacrificial piece.
If you can program the printer to stop at a desired height you dont have the need to watch the printer, dont have to be nervous about missing it and usually I can start the print looking quite good if I may say so myself.

But, this thread is not about how to change the filament mid print per se, it’s about a programmed stop at a certain height.

[SweHogelid]

Still waiting for a respons.
{REPLACE "; layer 10" "M600\n; layer 10"} Will not work on a (my) Ultimaker 2

@Doug_H Sorry for hijacking your thread but I hope you'll get something out of this as well.

[S3D-Alex]

Still waiting for a respons.
{REPLACE "; layer 10" "M600\n; layer 10"} Will not work on a (my) Ultimaker 2

@Doug_H Sorry for hijacking your thread but I hope you'll get something out of this as well.

Chances are good that your Ultimaker does not accept the M600. Not all Marlin firmwares have this command set up to be taken. If the M600 is not an option then the M0 with some scripting before and after will be your best option. Let me know if you need any help with the formatting I mentioned earlier in this thread.

[SweHogelid]

Thanks but I think I'll stick to my old way with waiting and manually pause.

[Wallabear]

Not to bash S3D, but take a look at how to do it in Prusa Slicer 2.0. Very fast and elegant, when I have to do a part with a filament change that is the slicer I use.

[Kasey00]

What I do on my Robo3D R2 is a little different. I make a second part, a skinny rectangular post (witness part), with a step in the rectangle shape (like transition to a rectangle half the width) at the height where I want to pause my print (usually to insert a magnet or threaded insert) and when I see the printer start to draw the reduced size rectangle on top of the witness part I hit Pause on the printer control screen. The printer pauses on the witness part, which I place behind the main part, so the head's back out of the way. Also the pause and resume cosmetic defects, if any, occur on the witness part and not the main part.

If hitting the exact layer is critical, one subtlety to watch is the order of printing of the parts at the layer when it's pausing. You need to step through the layers before and after the pause on the S3D preview to see if the visual change on the witness part occurs just before or just after it would have printed the layer over your desired pause on the main part. You should be able to tweak the height of the witness part a layer's worth and get that to change. I want the warning (printing border of outer wall on next layer) on the witness part JUST BEFORE the head moves over and skins over the pocket where I'm going to put the nut or magnet....

(I got that wrong once and had to reach in with tools while the printer was paused to remove some stringy stuff over the pocket I wanted to use. It was a little messy, but the print recovered after a few layers...)

I think this is easier to do than it sounds like here in words. The advantages are that the pause/resume isn't occurring on your main part, and the head's back out of the way, and you're not playing around in the control software. You're just printing a small secondary part as a reference. You could put another step in that part as a visual warning when you're getting close.

If you're not inserting things in pockets, and just changing colors or something, you might not care if you miss things by one layer height so that's even easier.

You might have to tweak the height of the witness part one layer's worth to fine tune that. Or move the part on the build platform to change the printing order perhaps. The S3D display shows the print head at the end position of the layer you're stepping through, so if it's sitting on the witness part, that's not what you want because it would have just previously printed that layer on the main part and now it's showing you that it stopped after the witness part.

[SouthernGoose]

Much experimentation later, I figured out how to do this on my Prusa Mk3s.

This is the gcode I need added at layer 14.
G1 X10.000 Y200.000 E0; park and get the prusa to stick its tongue out
M1; user stop
M105; return to current temp

So...
1. Figure out your row number (my number is 14)
2. Go to the FFF settings, Script tab, Starting Script, then look at the bottom where it says "Additional Terminal Commands for post processing.
3. Add this to the list of post processing commands
{REPLACE "; layer 14, Z = 4.050" "; layer 14, Z = 4.050\nG1 X10.000 Y200.000 E0; park and get the prusa to stick its tongue out\nM1; User stop\nM105; return to current temp"}

(note: you have to fill in your own layer number and z height EXACTLY as shown in the gcode so that it will do the find/replace correctly)
After you do this TEST it by exporting the gcode then search for your layer number to find the right spot. The result should look like this:

; layer 14, Z = 4.050
G1 X10.000 Y200.000 E0; park and get the prusa to stick its tongue out
M1; User stop
M105; return to current temp

This is the most ridiculous amount of stuff to go through to add a pause. Prusa Slicer uses an if statement and inserts the code at the correct layer for you vs doing a search/replace. This is something that lots of people need, not just me. Why not just add it as an option? I don't like the "filament change" option because you have to stop and pull the filament and reinsert. I don't need that, I just need a pause!