Can Ambient Temperture Contribute To Heat Creep?

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joshea
Posts: 21
Joined: Mon Aug 15, 2016 6:12 am

Can Ambient Temperture Contribute To Heat Creep?

Post by joshea » Fri Jul 27, 2018 4:12 pm

The title says it all, but I will explain a little more.

A week back or so, I had a large item print for about 7 hours overnight, and all seemed to go well. There was an issue with my z-axis going out align but that's another story (and that's already fixed). The print was done in PLA (Inland)

That next day I did a print for a friend using ABS, and I made sure to close the door to the room so it would stay warm in there (I have no central air in my house so later in the day a few of my rooms can get rather toast), it was probably 85F+ in there. Well unfortunately the print failed due to a filament tangle (didn't catch it for probably an hour or so sadly) so we switched over to some of PLA and was having horrible issues with the filament not sticking to the bed.

It was seeming to come out thinner then I would like, and wouldn't actually adhere to the bed, but drag behind the print head. I tried a few times, same results, finally gave up.

Last night I finally got around to performing some maintenance on the Taz 6, sanding down the bed with some 1500 Grit and 1/10 alcohol, 9/10 water mixture. I also went and readjusted my z-axis (no more grinding, yeahhhh), and spent time running Nylon and PLA through the hot end to clean it out.

Well today I started back up a print (same settings and model as my last successful one before the ABS issue), using PLA.It's probably 80-86 F in the room.

As the first layer is laid down I saw some weird results. Most of the time the filament wasn't laying down in a smooth layer, creating little bumps with small gaps, as seen in the photo. But not ALL of it was like that. One side did lay down a perfect smooth line (on the opposite side, which you'll see later, had the worst issues).
DSC07730.jpg
Then the first piece started in infill, and this was the results (ignore the right side I was slightly raising/lowering the bed with my force to see what a small move of the z-axis would look like)
DSC07737.jpg
Then we move to the back, it starts out messy (the infill, the shell was still bad), but then smooths out real quick, to more what I am used to seeing, except the far left, it flattened for a small section)
DSC07739.jpg
Then all went to hell. As the printer moved to the back section I started to see the effects of heat creep. The only reason you see layers on those at all, especially the farther right you go, is because I push down slightly on the bed to create a gap, almost like the bed was warped or something
DSC07742.jpg
And then the far right side, I at this point was giving up. Grabbing my camera to take photos instead of pushing down on the bed. What's interesting is the far right of this, going vertical, the filament laid down smooth and straight when it did the shell (or outline).
DSC07744.jpg
I finally killed the print, I knew all was lost. But I should point out I was pulling out a laser thermometer and measuring temps. The left side that printed the smoothest, did seem to have the lowest temps.

And this is what is making me wonder if ambient temp can contribute to heat creep? I recently moved, and my new place does get hotter then where I used to live. This is also the first summer I've had the TAZ 6, which I should point out has been my go to because it's so reliable and prints super well ... until now. So I have to wonder now with the hotter temps my prints are affected? I remember my Mini having issues with heat creep out of no where at my old place, and it was right around this time, where all of a sudden I found myself having to adjust the z-offset constantly just to stop heat creep.

All the signs seem to show I'll have to find a way to cool the room with printing PLA in the summer time, or over night, but I wanted to see if my theory was really true. Are others having this issue as well? Or is it proven? Where the ambient temp can affect prints enough to cause heat creep? And if so, what's a good way to mitigate against it? Lower the bed temp?

Thank you for reading this.
Proud LulzBot Mini & Taz 6 Owner!

kcchen_00
Posts: 1655
Joined: Thu Feb 19, 2015 12:42 am

Re: Can Ambient Temperture Contribute To Heat Creep?

Post by kcchen_00 » Fri Jul 27, 2018 11:09 pm

Sorry, I skimmed over your post. But based on the title of the thread, I would say, yes.

Sit in your car, turn on the fan without A/C. Then hit the A/C button, would there be a difference? :-)

JoeBowler300
Posts: 53
Joined: Thu Apr 28, 2016 12:20 am

Re: Can Ambient Temperture Contribute To Heat Creep?

Post by JoeBowler300 » Sun Jul 29, 2018 10:28 am

Quote taken from topic "Filament grinding" in General/Hardware/Lulzbot TAZ
viewtopic.php?f=36&t=7680 ; last post of the first page:
by mwester:
"Consider this thought experiment -- PLA has a glass transition temperature (the point where it softens) of about 140 degrees F (60 C). The goal is to keep the top of the heat sink below that temperature. If the ambient air temperature is 100 degrees F (in an enclosure, or closet, perhaps), then the differential between the air and the maximum temp is a paltry 40 degrees F. But, if the air temp is held at about room temperature (70 degrees F), that differential jumps up to 70 degrees -- a considerable difference when cooling."

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