Extruder temperature suddenly dropping.

[bot]

I've had one long print fail due to this and a second one almost fail.

Tall print, fairly large for ABS. Needs extra hot extrusion to help with layer separation.

First try, worked fine the whole way through, but I didn't like my infill or thickness settings, printed again.

Second time, extruder obviously got VERY cold (from 235 to 212) at a specific height and the layers just stopped sticking together.

Tried another time, different g-code, and same thing happens... at the SAME layer height...

It could be due to this part of the print jostling the head around a lot... maybe it's shaking a wire lose?

I got it to recover its temps by adjusting the bed temp down a bit and it helped....

Is this a power supply issue? Is my power supply failing intermittently? Is it a wiring issue at the hot end? (It looks fine... but it's covered in kapton)

Luckily I salvaged this print, it's been soooo perfect up until the near miss.

oops. I spoke too soon. The temp is back down to 210. The 14 hour print is at 92% if I lose this one I'm not going to be happy. I'm suspecting a failing PSU.

[Jimustanguitar]

The power supply theory would explain the temp differences, but there's nothing in a power supply that would cause it to fail at a specific layer height... That's the curious part.

[bot]

Haha yeah. After speaking with guanu some, we're suspecting a failing heating resistor or perhaps failing wiring TO the resistors. I was able to turn the heat bed temp up and not drop temp again... it's an intermittent thing. When the pritn is done I'll put a meter on the leads and see what the resistance is.

[BenTheRighteous]

Could very well be a loose wire. Perhaps when you're printing at low layers, the bend from your wire harness is small and the loose wire makes a sufficient connection. But at higher layers, your wire harness is coming in at a different angle and that's enough to weaken the electrical connection.

[bot]

Could very well be a loose wire. Perhaps when you're printing at low layers, the bend from your wire harness is small and the loose wire makes a sufficient connection. But at higher layers, your wire harness is coming in at a different angle and that's enough to weaken the electrical connection.

That could definitely be it. We won't know until I look! I gotta finish the rest of this print first (none of the remaining pieces are as tall... so hopefully they don't run into the intermittent issue.) It also could be in the quick disconnect connector I have. I kinda squeezed it when the temps dropped and shortly after they climbed back up.

[bot]

Well, precisely where the extruder temp dropped the pieces just CRACKED.

there goes another print. I've lost almost a quarter spool of filament to this issue... and the temps dropped AGAIN!

This really sucks and couldn't have come at a worse time.

[BenTheRighteous]

Oh no, that sucks! If it means anything, you've got my sympathy...

[bot]

Well it seems the wires got hot and melty right where the uninsulated crimps are near the hot end. Hmmm. Wonder why that is. Gonna redo them and see how long it lasts.

This is actually gonna be pretty tough to fix without damaging the thermistor or resistor leads.

[jdurand]

A bad solder joint can cause that. Pretty hard to fix as the metal is now oxidized. Be sure to CLEAN to bare metal and use GOOD flux when reattaching.

[JFettig]

You mentioned different g-code... did you check the screen to see if it is commanding temperature change or if its just happening?

[bot]

Ten four, jdurand. Though, there was no solder in this joint.

Jfettig, absolutely positive. I disabled plugins and saw the screen say target 240 while it was at 203, 199, then I cancelled the print.

Got some new crimps. Wish me luck. Might have to play surgery with the tiny leftover resistor leads.

[bot]

Well here we go! This was wayyyyy too easy to remove. Oops .

I also filled in some RTV where some cracks had developed, per guanu's expert advice (he really does know his stuff).

I actually did fill it in, you'll just have to trust me. I'm not gonna wait til it'll cure. I'm sure with 240C it'll cure in no time!

[bot]

I crimped it back together and this time it won't slip off! (DOH!!) Well, it didn't fully slip off by itself, but I could pull it off without much effort haha. I tested the resistance and it is hovering around 3-4 ohms. That's bang on right?

[JFettig]

Sounds right.

When I crimped mine, I noticed that it didn't like to crimp very well and had to crimp it a couple times. I was tempted to solder as well but didn't.

[jdurand]

It's really hard to get a good crimp on solid wire, the terminals and crimper jaws just aren't designed for it.

Things I do when faced with that:

Fold the solid wire over so I have two strands, that will crimp MUCH better.

If the above isn't practical, I add a bit of some other wire along with it. Again, much better crimp.

[bot]

The crimps I got this time were a snugger fit to begin with, and I wasn't afraid of damaging anything this time (cause what have I got to lose, right?) so I squeezed extra hard. I actually remember when I did the crimp originally thinking (meh this isn't great... let's see if it'll last.)

Follow your gut.

I couldn't get the red off without mangling everything, so I left it as is. It's a bit blackened, but not like the negative terminal was. So hopefully it gives me enough time to finish this print.

All that being said, this crimp lasted 240 hours of print time!

[bot]

Aaaaaaaaaaaaand we're printing again! It's working just the way it's supposed to for now. I also oriented the hot end in the effector so that the wires had plenty of "air cooling" (as much as theyd get being there) and kept it away from the nuts, screws and fan shroud. Should be good to go.

Lesson learned. EVERY DETAIL COUNTS. Do every single thing perfectly or you'll be doing it again.

[geneb]

I spotted this on Reddit last night. Good job Bot!

g.

[BenTheRighteous]

I spotted this on Reddit last night. Good job Bot!

g.

Thanks for giving us the Reddit heads up, otherwise I might not've put 2+2 together...

Nice shower curtain enclosure! I'm debating doing the same thing myself. Do you find that it's helpful or would you recommend doing the proper thing with PC instead?

[bot]

Thanks gene! I'm glad I was able to sort it out quickly.

I'm finding the enclosure very useful. Although I also put a little 700w space heater in the room. It's actually a mattress cover, not a shower curtain. Entirely temporary for now. (The plastic is very thin, won't last. Was $6.)