Unresolved R1+ temp fell too much... but hotend is good

Hi all,

A few weeks ago my R1+ started stopping mid-print with the Extruder switched off. Temperature fell too much during print error. Due to prior experience and also the FAQs I thought it was an issue with the thermistor making bad contact with the hotend. I tried to unscrew the thermistor and then rescrew it more properly, but unfortunately ruined that hotend in the process.

I have since then ordered and replaced the hotend with a fully new one. I managed to get a couple of prints off, but then I started getting the same error again, so it seems the hotend was not the root cause.

I have also already tried the FAQs suggestion of disabling the print van: to no avail.

What are the other probable causes for this issues now? I tought

1. Faulty wiring from hotend to RAMPs board? This would be a pain to diagnose and/or fix I think
2. I see the FAQs also mention "There is too much air moving around the hotend". The air temperature right now is usually around 12ºC. The printer typically operates in a closed room without anyone else in there; it is roughly in front of a window that I keep only slightly open on the top (like this ). This it is likely that just the airflow could cause this? How would I go and improve this, assuming closing the window would be a bad idea?
3. Others?

I'd really appreciate any help in getting to the bottom of this and hopefully fixing it. It's so frustrating to have such a complex machine that has 99% of its components working but is rendered kinda useless due a single faulty one

Thanks in advance,
Filipe

PS: I don't get the Extruder switched off. Temperature fell too much during print error right at the start of a print. It is often well into it, sometimes only just after like 6h of printing

 

12C is pretty cold for room temperature, so that may well have something to do with the problem. Likewise if you keep it next to an open window through which cold air can flow. Can you move the printer elsewhere, even temporarily, to run some tests?

 

@mark tomlinson and @Rod Smith thank you both for your inputs.
@mark tomlinson I have turned the printer around to get access to the RAMPs board and disconnected and reconnected the thermistor connector on that side. After that I managed to run a 6h print successful, and am now midways on a second. Still too early to call victory though...

If it fails I'll probably try a few prints with the window closed to remove airflow, to see if that's the issue.
If that fails I guess I will have to try and replace the thermistor cable from hotend to RAMPs

In the meantime I got in contact with ROBO official support as well and, besides the same recommendations you guys made, they also said
You can also do a PID tuning on your hotend to tune the thermistor and heat sequences to see if that would help too. Check here to see how to do that https://matterhackers.dozuki.com/Guide/PID+Tuning/6
Do you think this might help as well? If so I might try that before replacing the cable

Best regards,
Filipe

 

Yes, PID tuning is a good idea. It won't help if a cool breeze or something is overpowering an old/weak heater cartridge, but if the heater cartridge can heat the print head, just slowly, a PID tune might keep the printer from freaking out at the slow heating.