PLA Jam

[pyronaught]

I almost never use PLA. I was trying to change out a printer from PETG to PLA and the nozzle jammed when feeding in the PLA to set it up. I had the temp set to 195 initially and it started to feed, then just stopped. So I figured maybe that wasn't hot enough to melt the PETG that was previously in there and started increasing the nozzle temp to try and get it to flow, but the thin string of plastic coming out the end refuses to melt. It's like pulling on cold plastic, even with the nozzle temp set as high as 265. Is there some kind of bad chemistry when these to filaments mix? Does PLA gum up if you heat it beyond a certain temperature? No amount of pushing the filament into the nozzle manually can get it to budge. The thing is just frozen up rock solid. How the heck can you change between these two filaments?

[3dPrintingMD]

Heat it up to 220. That is the high end for PLA and the low end for PETG. It will eventually ooze out.

Or, retract out the PLA, jack up the heat to PETG levels and try to load PETG again, that could help to clear out the jam.

[Jules]

eSun sells a Cleaning Filament. It's rather horrible to use, but it does work to clean out the leftover PETG in the nozzle so you can switch to PLA, and vice versa.

When you use it.....set the temperature at the correct extruding temp for the filament that you have just removed. (So in your case, PETG temp of 245° or so.) Extrude a few inches until the thread comes out clear/white from the cleaning filament, with none of your PETG filament color showing. Reduce the temperature to the PLA temp, extrude a bit more of the cleaning filament, and then retract it completely out. Then you can load the PLA filament and it should flow. Extrude some of that to chase out the cleaning filament remnants, and start your print.

Unfortunately, the cleaning filament tends to get squished out of round on the spool, so you might have some trouble feeding it in - I cut 6 to 8 inch long lengths and just feed one in at a time, by hand, lightly forcing it down if needed, and sometimes I gently squish it back into a round shape with pliers before trying to get it in there. It can cause jams. But it's the only thing rated to both temperatures.

If you don't use cleaning filament every time you change to a different type of filament, your options are to do a cold pull, or take a blowtorch to it. (The cleaning filament wins....barely.)

[pyronaught]

Right now there a mixture of both PLA and PETG clogging the nozzle. I can't even get a slow ooze or anything out the tip. What is stuck in the tip is solidified, so I can't even get a drill bit into it. It's as if these two filaments are part A and part B epoxy or something.

When I first got my 3D printer I used PLA and had a nozzle jam the first week. I went through the whole blowtorch thing and eventually just wound up replacing the damn nozzle. I stopped using PLA after that and never looked back. I'll never understand why that filament is so popular-- I've never had anything else jam nozzles the way it does.

[Jules]

The problem is that PLA can carbonize at high PETG temperatures, and PETG doesn't melt well at low PLA temps.

Just use the cleaning filament between and there's no problem. I switched back and forth dozens of times between the two filaments on one nozzle (before going dual).

[pyronaught]

I've just been having REALLY bad luck with 3D printing the last two days. Just weird stuff happening I've never seen before... on multiple jobs and multiple different printers. Nothing changed from the way I've always been doing things with no problems. Now I've got a PETG nozzle jam which I've never had happen before.

[Jules]

You have had a rather extraordinary streak of rotten luck lately.

[insta]

I've just been having REALLY bad luck with 3D printing the last two days. Just weird stuff happening I've never seen before... on multiple jobs and multiple different printers. Nothing changed from the way I've always been doing things with no problems. Now I've got a PETG nozzle jam which I've never had happen before.

Keep it up, I've been having great luck

I like to think there's a universal pool of printer success and right now I'm basking in all of it.

[Jules]

I like to think there's a universal pool of printer success and right now I'm basking in all of it.

So that's where it went! I haven't been able to print anything bigger than a golf ball for months! Not because of problems with the machine, but because of freaking #%v@$&* thunderstorms, that strike without warning.

Give everybody back their share of the luck now, you've had it long enough.