issues after filament change

Hi,I have a Creality Ender-3 Pro and am using a PLA+ filament. I edited my firmware to enable print pausing via the M600 command inserted into my gcode so that I can change filament colors at certain levels. Everything works fine with it, except when I resume printing, the filament doesnt stick to the existing part that was already there. Im fairly new to 3D printing, but my thoughts are that maybe its because the bed has cooled down? Or maybe when the print head returns to the part, the z axis may be too high? All guesses of course! If anyone has any thoughts on this, please help me out. Thanks!

The bed should not have cooled down sufficiently to affect the print, especially when one considers that the bed temperature is related to model adhesion and not to inter-layer adhesion.

Consider to edit/add the temperatures you are using, as well as the recommended temperatures for the filament. It's possible that you could solve the problem by kicking up the temperature another five or ten degrees for the layers after the print resumes.

OK, So I added another M code right after the filament change to heat the filament to its maximum range which is 220 before resuming the print. I started the print at 200, which is the minimum. I also slowed the print speed down from 50 to 30 thinking this might help. I still have the same issue though.

Quote:

---

Originally Posted by fred_dot_u

The bed should not have cooled down sufficiently to affect the print, especially when one considers that the bed temperature is related to model adhesion and not to inter-layer adhesion.

Consider to edit/add the temperatures you are using, as well as the recommended temperatures for the filament. It's possible that you could solve the problem by kicking up the temperature another five or ten degrees for the layers after the print resumes.

---

Slowing the speed was a good idea. With all you've done, it leaves an inaccurate return to location. Examine the position of the z-axis screws at the point of the pause. Perhaps add a masking tape flag to the top or bottom of the z-screw to better see the location. When the printer pauses, it will be in one direction. When it resumes, is the location skewed?

Well, the best I could tell, it was coming back to the correct location. So as I was about to give up, I had a Eureka moment and decided to run the print again, still with the pause, but this time I did not actually change the filament... I just left the same filament in and resumed the print. All worked fine this time. I switched out the filament to the other color I was using and repeated the print without actually changing the filament and again it worked just fine. I thought about it for a minute and realized that I have 2 different brands of filament, so there must be something in the chemical makeup of the 2 different brands that doesn't play well with the other. I am considering my issued solved. My take from this will be to stick to the same brand of filament, at least for multi-color prints. Thanks for the help! Hopefully someone else can learn something from this thread!

Quote:

---

Originally Posted by fred_dot_u

Slowing the speed was a good idea. With all you've done, it leaves an inaccurate return to location. Examine the position of the z-axis screws at the point of the pause. Perhaps add a masking tape flag to the top or bottom of the z-screw to better see the location. When the printer pauses, it will be in one direction. When it resumes, is the location skewed?

---

That's something I would not have considered to be a factor. You are correct that someone else (me) will learn from this.

OK, So I figured that I should update this post so I dont feel like I put some bad information out there. I was completely wrong about the brand of filament being a factor here. I finally stumbled on to a solution that I tweaked a little and now I am having much better luck. Here is my solution:First off, you MUST have the ADVANCED_PAUSE feature enabled in your firmware in order for this to work! Then, if you use Prusa Slicer, you can simply add these lines of code into your Custom G-Code section of your printer settings:After layer change G-code:M104 S{first_layer_temperature[0]} ;reset nozzle temp back to final tempM220 S100 ;reset feedrate back to 100%Color change G-code:M600 ;change filamentM109 S{5+first_layer_temperature[0]} ;increase nozzle temp by 5 for this layer, will reset on layer changeM220 S40 ;reduce feedrate to 40% for this next layer, will reset on layer changeand then simply use the preview slider in order to add color changes.If you use Creality or Cura slicer, you will have to manually edit the gcode file in notepad and add the code before and after the layer where you want the color change to happen. You also need to replace the variables ({first_layer_temperature[0]}) with actual numbers.