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Rat Rig Community [Unofficial]•2y ago•

32 replies

iKuro

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: