Possible Overheating causing Hot End Failures?

[JohnStack]

It gets tiny little nubs that don't stick, and then no extrusion through the head.

As soon as I see it, I look at the temps but they appear normal. I ran this print mainly at 225 - 230.

At that point, the extruder eats through the filament and naturally, quits pushing it through.

Here's the interesting thing:

When I started this round, I didn't do anything to the hot end. It had jammed but I just cranked it to 240 and it pushed filament out. I thought what the hell so I launched this job!!!

I'm going to buy another power supply tonight and try again. Not with a 19+ hour print but....

Lastly, I sure would love to know why print speeds slow down over time...

[geneb]

If the temperature isn't dropping, your power supply isn't the problem.

g.

[JohnStack]

Several hot ends later, a new servo, different power, a new Rambo 1.2, I have no clue.

I have replaced or upgraded the entire supply chain Gene.

[Eaglezsoar]

Several hot ends later, a new servo, different power, a new Rambo 1.2, I have no clue.

I have replaced or upgraded the entire supply chain Gene.

I have to agree with Gene, replacing the power supply is not going to fix it.
We need more information, we based the previous assumption on the temperature
dropping. Now you indicate that it is not dropping. I understand your frustration but
if you can document on here exactly whatever facts you can think of at the time of failure.
If you buy that power supply you will be wasting your money. There are people on here
that will help you. Document what has happened, why you replaced the hotends so many
times, etc.

[JohnStack]

(I understand there are people to help....thanks)

I've been very systematic. I replaced the hot ends for the exact same failure.

I thought it might have been them. In order: an E3D, tried another Rambo 1.2, and then two SeeMeCNC hot ends.

I get little nubs that indicate failure. They're not really connected to the plastic - like oozing would be. When I see them, I look at the temps, they appear fine and by that time, the head is a layer up, with no extrusion.

Can't be filament - since the failures are too random and SeeMeCNC has been buying good stuff.

My connections are solid. They're blade connectors. Nothing is loose inside. I look at all of that first. In fact, if I have a problem, I go through wiring first.

It's either that my office is overloaded or after a year, my power supply is starting to fail. I've crawled all over this thing either making it more solid or resolving what I think might be causing it. After having built a few of these, I don't see it.

The only other draw on this is are LED lights and I have a switch for them...I don't always keep them on.

So, to me, a new power supply is cheap and as I'm building a Kossel Mini, there's no waste anyway. I will also run the printer from a different circuit in the house and see if it's not my office's power.

After the new PS, I'll rebuild every circuit with new wiring, stick on a new power supply, put a fan on the back of the board, and start fresh. I've done enough with incremental change on this problem and "see if it's this" kind of problem solving. Unless there's something obvious, it's not worth the time or the wait. It's been over 50 hours on this problem...

[Eaglezsoar]

Those little nubs that you talk about sound like what is left over after a retraction. I get the little nubs also and I know what causes them on my parts, retractions.
Your problem now sounds more settings related then hardware and I am not the best to advise you on prevention of the nubs forming on your prints because I can't
stop them from happening on my own printers. Gene, if you have any suggestions your advise would be appreciated as well as anyone who can advise John on how
to minimize or completely stop these "nubs" from occurring.

[Polygonhell]

It gets tiny little nubs that don't stick, and then no extrusion through the head.

This is fairly typical of a PLA jam, or some other form of filament starvation.
What plastic, what temperature, what hotend are you currently printing with?
Have you measured the hotend temperature with a thermocouple?

[JohnStack]

The data - the Rostock Max is my ABS printer...

Putting a temp probe into the hot end tip receptacle, I get good reads at 230 or 235 - whatever I set it at.

This last print was 19+ hours straight - one part. Before putting on a separate power supply for the bed, I couldn't get over two hours of printing before a failure.

The nubs occur only when a failure is going to happen or has happened. No observed drop in hot end temps - but I'm going to have to not use the SD card to find out otherwise.

I think it is heat or power. After 19+ hours, I don't think it would be settings. Not to be flippant, but I'm pretty sure there is nothing to change there.

[Polygonhell]

Then I would suspect filament starvation.
There are only a few things that can cause this with ABS, it's likely mechanical, unless the extruder stepper or the board is overheating, but that seems unlikely after 19 Hours.
Variation in the composition of the plastic on the roll or plastic jamming in the Bowden tube, or the hotend body, the latter is the most likely culprit, this can be bad plastic, but it can also be caused by overly aggressive retraction settings and a part of the print with a lot of retraction, the E3D seems particularly susceptible to this, I think because of the very short transition zone, basically repeatedly retracting causes the molten plastic point to creep up the hotend, and potentially "set" above the thermal break.

You can trivially rule out retraction by printing with it turned off.

I've seen plastic where some parts of the roll required a good 10C more to print than other parts, so you can try pushing the temperature up a bit.
If you can catch it as it happens, you can try letting disconnecting the extruder and trying to move the plastic in the tube by hand, if it's difficult, you can disconnect the bowden tube and try and diagnose where it's happening and what the diameter of the plastic is at that point (you're looking to see if it's on the high side of the nominal diameter). Contaminants in the plastic can also cause the issue, but that's unusual.

FWIW I've never used SeeMeCNC ABS, so I can't comment, but the rolls of PLA I bought from them were as bad as the cheap Chinese stuff I won't touch or recommend. It's one of the few times I've been disappointed by their products.

[JohnStack]

Ok. Next up:

Turn off retraction.
Change out PS (anyway, cause I can)
Stick a fan on the board

Should make for an interesting weekend. I'm definitely not going to print an almost solid Yoda again but we'll see how she runs on a print for 5 - 6 hrs.

Two last things to note that I thought of:

It's not creep - because the jam is always on the south side of the bowden tube.
I replaced the bowden tubes with what SeeMeCNC uses.

[Eaglezsoar]

When I left my message about the formation of the nubs, I completely ignored the fact that the print ran for 19 hours before the problem occurred.
Before the power supply was added to feed only the print bed, the longest it could print was approximately 2 hours. This is a very perplexing problem.
I have asked John to reduce the cold extruder stepper current but at this point both of us are just guessing. It is going to be hard to diagnose a
problem that only shows up after 19 hours of printing. We have made huge gains, as listed above the problem used to show up after 2 hours, now it is
19 hours. We would want the problem to disappear altogether, at least that is the goal.

[geneb]

I almost wonder if the stepper is just defective enough that when it gets hot, it doesn't perform as well. Or maybe it got badly overheated at one point and the heat weakened the permanent magnets. Do you have a different stepper you can try in the extruder?

g.

[Eaglezsoar]

I almost wonder if the stepper is just defective enough that when it gets hot, it doesn't perform as well. Or maybe it got badly overheated at one point and the heat weakened the permanent magnets. Do you have a different stepper you can try in the extruder?

g.

Good idea Gene! It is certainly worth a try.

[JohnStack]

It occurred to me that the upgrade kit would come in really handy right now since I'm going to conduct major surgery.....

Bought an Antec VP630F 630W power supply, the only downside is the massive amount of extra wires. I would have gone modular but the price difference isn't worth it yet - primarily since I know this will work nicely with the new upgrade (coming when?)

Gene, I have about ten extra servos.

I'll stick a 50MM fan in the engine compartment.

And, I guess I'm going to move this thing out of the office or at least onto a different breaker.

Lastly, I am well-stocked on Stone Brewing Company IPA.

[JohnStack]

Ima lucky dog. My breaker panel is behind my workbench. I dropped in a new line directly below it on its own 30 Amp circuit. That circuit will only have the printers and their respective PCs. Next up, completing the rebuild.

[Edit] I'm a normal dog. Lucky that I have a new dedicated circuit for printers. Unlucky that the power supply I purchased doesn't supply any power. Back to Fry's.

[Eaglezsoar]

Ima lucky dog. My breaker panel is behind my workbench. I dropped in a new line directly below it on its own 30 Amp circuit. That circuit will only have the printers and their respective PCs. Next up, completing the rebuild.

Don't forget Gene's idea of changing the extruder stepper, then you will have changed everything in the machine except for the wood.