Pausing then restarting mid-part

Today I had to pause the printing process because I was going to run out of ABS filament before part was complete.

I was hoping I could pull the old spool, and replace it with a new spool and hit “resume” without missing a beat.
The part I was making wasn’t critical to having a perfectly smooth and clean finish.

I hit the pause button in pronterface and was hoping the software would lift the extruder nozzle off part and find a temporary “home” until I hit “resume”.

That did not happen. Pause just stops the prinitng, but the hot nozzle sits on part and starts to make a larger mess than I wanted. In the end, I had to trash my partial part, and restart from the beginning.

What I’m wondering is if there’s a process for stopping and then resuming the print for things like replacing the filament reel when you run out of filament mid-print?

Thanks for the advice.

When changing filament mid-print, I like to pause it during the perimeter portion of the print, so that it finishes the buffered commands and pauses somewhere in the infill portion of the printing process.

When using Pronterface, whatever moves you make when paused will be noted and undone when resuming a print. If you do so with the Graphical LCD controller, the same will happem, except for any Z axis moves. For some reason Z axis moves after a pause are not compensated for when using the Graphical LCD controller.

Once paused, I typically don’t move the hot end if it’s inside the model. It’s easier that way for me to reverse the filament, and load it. Typically, at the scales I print (printer parts) the filament transitions to the new color by the time the infill portion finishes and transitions to the new perimeter.

What I do is to move nozzle away from the print, and then return it when change filament.
But make sure to move it the same amount back and forth.

Let’s say you print and decide to pause.
(for ABS)

  1. Hit Pause
  2. Move in Pronterface (or whatever you use for print run) by 100mm X or Y axis whichever suits you
  3. Cool nozzle to 120C
  4. Slowly pull out the old filament it should come out as a whole
  5. Heat up to 230C
  6. Put in the new filament
  7. Extrude until you get the desired color (if you had changed colors at all)
  8. MOVE IT BACK the same amount you did to move it away
  9. Quickly hit Resume

step 9 should be done quickly in order for ooze not to pile up

that is what worked for me several times now

the only problem is layer delamination in contact surface, because the print will cool off while you change filaments
…but that’s another topic

No, sorry i totally support the freesource mentality of lulzbot and pronterface;however, ditch pronterface, use repitier and be fast! You can hit pause, lift nozzle 10mm and once you hit resume she starts again from where she left off without going down manually again (because i normally just spam click to raise the nozzle up).

Ive written a script for this as well that you can insert into repetier GCODE at any point (if you know for sure you want to do a colour change. running out of a material mid-print is another story).

Well, what happens to ooze when you lift the nozzle? There is always a string that will remain like a needle when you lift hot extruder

I can clean the nozzle 100 times in 30 seconds if i’m prepared and ready to move fast so ooze is nothing:P

Keep in mind that the printer completes up to 10 “moves” until it actually pauses.

I use Repeteir to figure out where to insert my script by highlighting the GCODE layer in yellow. My script that i insert into Repetier does the following:
Pauses print > lift nozzle 60mm(lift higher with more viscas plastics like wood) > retract 60mm
Then all you do is put the new filament in and hit resume after your done watching your movie…
Keep cleaning the nozzle mm’s before it starts again.

Its not a good habit to leave your hot end sitting hot for hours, and with this script, your kind of destined for failure so i would just recommend manually hit: pause > lift nozzle 60mm> retract 60mm and work fast on the ooze and hit resume when loaded.

This is great for nice controlled filament banding of colours! I have considered inventing a spring loaded double-filament guide/holder for the taz. It would retract the current filament out completely and then trigger a spring loaded switch/gears (via retract or extrude command) that would jam the next filament in the chamber. Colour banding could be done automatically via script… anyone think this is a crazy idea?
I got this idea becauseThe TAZ is fairly easy to load new filaments compared to other printers.

Many of the parts I mass produce have two colors so I am always dealing with swapping filament mid print. I have gotten the process down to under 10 seconds from the time I hit pause to the time I hit resume. What I do is cut the filament off about 4" above the extruder head while it is still printing. I then unwind the spool to pull all the filament out of the guide tube. I then load the new spool and fish it along the guide tube until it pops out on the end. I now have the new filament ready to load while I still have a couple inches left of the old filament sticking up above the nozzle. I then hit pause and quickly lift the tensioner lever and pull the old filament out. Since it’s still hot it removes very easily. I toss that little left over piece in the trash and immediately slide the new filament into the nozzle, drop the tensioner back down and hit resume. It goes very quickly. The key is to have the new filament loaded and ready to go BEFORE you hit pause. Been doing that for months now on well over 100 parts and it has worked every time. since the nozzle is only sitting in one place for such a short period I don’t get too much melted damage on the print. I also wait until it’s doing infill before I hit pause and not a perimeter.

I am printing with a taz 3 via the sd-card. I have had success cold pausing–in order to leave the machine unattended for a while–and then restarting, all via the lcd display.

Step 1: pause the print while printing infill.
Step 2: Take note of the z position and write it down.
step 3: Prepare=> move=>1mm and quickly move the extruder away from the print along any axis.
step 4: Prepare=>cooldown
Step 5: leave the machine plugged in and do whatever you need to.
step 6: return the machine and select prepare=>preheat
step 7: select Prepare=>auto home
step 8: Now via Prepare=> move=>.1mm move the z axis back where it was when you paused the print
step 9: Once the printer has preheated selected resume print.

Does anyone know of a better way to do this without being connected to a computer?

If you turn off the heatbed, wouldn’t the print start to cool off and probably the next movement would detach it soon enough?

I just had to do this today and I never had to pause the printer. Instead, I fused the beginning of a new spool to the end of the old one, so the printer just kept extruding seamlessly. Here’s what I did:

When there was only a meter or two left of the original spool I removed the filament from the spool itself and trimmed the end so it was a smooth surface. I also trimmed the end of the new spool. Then, being careful not to pull on the original filament at all, I used a lighter to slightly melt the end of both strands and mushed them together. This fused the old and new strands of filament, but left a big bulge of melted plastic, so once it cooled I trimmed that off with an exacto knife and then used 1200 grit sandpaper to smooth the joint. Finally, I used just a little bit of a 10% alcohol solution to clean the sanding dust off the joint and dried it thoroughly.

This worked like a charm and didn’t interrupt the print at all. A few things to remember if you’re going to use this method though, 1) when working with the end of the original strand be very careful not to put any tension on it. Make sure you do this while there’s still at least a meter or two left in the original spool. 2) you need to make sure the two strands are aligned and smoothed as closely as possible. Ideally when you’re done with the joint it should look like there’s no joint at all. Otherwise the joint could get caught in the feed tube or inside the extruder itself.

(p.s. You might be able to chemically weld the two strands together and get a clean joint without trimming or sanding, but I actually tried this first using acetone on my ABS filament and couldn’t get it to bond well enough, so I just melted it with fire)