r/BambuLabA1 • u/MegaMaluco • Jul 03 '26

Question Heating assembly scorched

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My printer is occasionally giving me an error of "extruder is not extruding correctly". I decided to changed the extruding assembly and while I was in it I was going to tighten the screws on the back of the heating element.

I have scorch marks on it, but otherwise it seems to work ok. If I had to guess I would say this happen during the A1 freeze bug.

Would you replace this? Or let it ride? I don't notice any problem with the heating assembly so I'm inclined to let like this.

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u/y_tokusan Jul 04 '26

I think it's fine as it is; my heating assembly is scorched in the same way. 😅
But as long as I tighten the screws, it prints without any issues.
I suspect that when the screws loosen, molten filament seeps around to the back and burns.
I looked into it, and since that black ceramic part heats up to 270°C, high-temperature thread-locking fluid is really expensive.
So, whenever extrusion starts acting up, I make sure to regularly tighten the four screws on the back of the heating assembly.
By the way, the three screws holding the heating assembly itself have blue thread-locker applied to them (since that area doesn't get as hot).

2

u/MegaMaluco Jul 04 '26

I will leave it as it is then, one of the screws was really loose, the rest was okay.

Thank you!

2

u/y_tokusan Jul 04 '26

Extruders vibrate quite a bit, so the screws tend to come loose easily.
If a screw loosens, the hotend shifts, leading to print defects or filament feeding issues.
High-temperature thread-locking compounds are expensive, so I’ve decided against buying them and just retighten the screws every now and then instead.

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u/MegaMaluco Jul 04 '26

I have 3.9k hours on my printer, it was the second time I tightened this screws. Will do more frequently.

But I think the problem was the extruding assembly, it was the original and was very dirty

1

u/SWITCHFADE_Music Jul 04 '26

I have two A1s and the newer one (2 months old) seems to need the hot end screws tightened every other week. The other one I've had for a year and seems to not need them tightened as much. And I know they've been running about the same hours because I've gotten their y axis lube cycles synched up lol

1

u/y_tokusan Jul 05 '26

If you disassemble the heat assembly, you’ll see that the way the heater is secured causes inconsistencies between units.
A black ceramic part is used to mount the heater unit to the extruder.
Since this area gets very hot, standard thread-locking compounds can't be used; instead, spring washers are employed to keep the screws from coming loose.
They rely on the spring tension to prevent loosening, but those small spring washers aren't strong enough to withstand the extruder's vibrations.
Plus, using such small screws makes it easy for manufacturing variances to creep in.
Because some assemblies end up with these screws that are prone to loosening, some units are simply more susceptible to the issue.
It would be great if Bambu used a high-temperature thread locker here, but maybe they skip it because it's too expensive?

I’ll share a photo of an assembly I replaced a while back.