Rapio 2 UHF thermal runway issue

Hey, testing a theory 😄 So, I've modified my printer - V-Core 3.1 "classic" (without enclosure) but it's enclosed by me. I've swapped the Toolhead from Beta 2 to V1 Updated Ratos from 2.0 to 2.1. Before these mods I easily could print @250 degrees and 100% 4028 Fan. After those I managed to get 8hr of print time - 5 at PLA 220 100%, then around 3hr at PETG @250 and 50% Fan. My last print failed due to thermal runway - fan at 100% either cooled the hotend, or the hotend didn't heat in reasonable time. After that, I didn't manage to perform the PID tuning properly either at 220 degrees with fan or 250 with fan. Without fan it works ok. I've asked about this in hotends-and-extruders channel but was pointed here. So what I did: - Replaced thermal paste on heater element - Checked cable loom (everything is okay) - performed multiple tests on different temps and fan speeds. - Checked the difference in design between beta2 and V1 - The fan duct is 3mm higher in the latter. So, what to look for? In the attached images You can see that the curve works well, just the printer returns fault "too early". The heater element is able to keep up, but it's "slower". Every time it faulted, the heating started as normal. Sometimes it fails after couple cycles, sometimes immediately. It always is able to reach the set temp with fan on. - Do You know what is the reason for the change in V1 and Beta2? To me it seems like it actually is blowing partially on the hotend instead under it. - Has anyone experienced an issue where thermistor works properly (there is no noise in reading) but is loose? I've checked and I would say it's tight. Temporarily I modified the [verify_heater extruder] to increase the tolerances for the fault, but would say this is a false approach.:ratrig:
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18 Replies
SwissStar_BL_2
SwissStar_BL_2•2mo ago
Just to be sure: you use the right lenght silicone sock on the rapido?
iKuro
iKuroOP•2mo ago
xD Yes. the longer one. There is no visible space between the sock and radiator and You can only see the nozzle :d Before update I've managed to print 250* and part cooling at 50/70% without issues really
SwissStar_BL_2
SwissStar_BL_2•2mo ago
Is there any chance you damaged the ceramic heater while upgrading? Had the same problem recently, turned out to be a broken ceramic heater
iKuro
iKuroOP•2mo ago
How did the problem work for You? It did heat but "not enough" ? I dissasembled it yesterday while swapping the paste, but basically everything seemed fine on the ceramic element. I i do not know about the wires though Also I think electrically everything is okay, but the V1 toolhead raised the air duct a bit, In the past I had similar experience where the cooling duct was coolign the heatblock instead of the print
SwissStar_BL_2
SwissStar_BL_2•2mo ago
Yes, the curves looked exactly like yours. It was to "slow" with heating, so klipper shut down after one or 2 peaks. There is a thick heatsock around the heating element, i doubt that its strong enough to overcome the whole insulation from the silicone. But who knows. Do you have the old parts laying around to check if the problem is only with the V1 toolhead?
iKuro
iKuroOP•2mo ago
Yes, I could manage to do it. PID tuning @250 without the fan works fine for me though. Was it like that for You too ? Yeah but the nozzle is sticking out. The more air touching the hotend, the better chance of it being cooled down - that's my thinking
SwissStar_BL_2
SwissStar_BL_2•2mo ago
I didn't try without fan tbh
iKuro
iKuroOP•2mo ago
So... any idea where to source the heater? Only option I see is the aliexpress. Before buying I will test it anyway, but You know, trying to cover all my bases
SwissStar_BL_2
SwissStar_BL_2•2mo ago
Where are you located? I did not find anything other than Aliexpress in europe. West3D in the US has the spare parts in stock
iKuro
iKuroOP•2mo ago
Europe/Poland So, did it work fine for You? Which one did You buy ?
SwissStar_BL_2
SwissStar_BL_2•2mo ago
Sorry, wrong. I did buy the part from JB3D in the UK https://jb3d.uk/product/phaetus-rapido-2-ceramic-heating-kit/?v=d88fc6edf21e
iKuro
iKuroOP•2mo ago
Thanks. so just to confirm. You are running the Toolhead V1?
SwissStar_BL_2
SwissStar_BL_2•2mo ago
No problems since i changed it. But i don't know if it helps in your case
iKuro
iKuroOP•2mo ago
sure 😛 I know
SwissStar_BL_2
SwissStar_BL_2•2mo ago
A modified Beta V1 How high are you running your fan for the PID tuning?
iKuro
iKuroOP•2mo ago
30% Manages to recreate the fault but 100% at 220 is ok
SwissStar_BL_2
SwissStar_BL_2•2mo ago
I personally don't think the problem is the higher position of the duct. 30% should not cool the nozzle that hard that the heater fails.
iKuro
iKuroOP•2mo ago
I agree that it shouldn't be an issue. I've yet to look for air leakages, and I will try to look closer on the heating element itselt, maybe I really did pull the wire away from it a bit and there is not enough contact Ok. Sat down to the printer. Checked the PT1000. It was just a tiny bit loose. After tightening - it was fixed. Thanks for the help!
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