Some issues with mk2  

Re: Some issues with mk2

thermal runaway: possibly a bad thermistor connector. reseat or replace with soldered connection. see http://help.prusa3d.com/mk2-electronics/thermal-runaway-and-temperature-drops

Re: Some issues with mk2

but it didn't happen when i print with slic3r code right after that message (3 prints total time 2 hours)

Re: Some issues with mk2

If your Thermistor is a 2 piece connector just double check to make sure its seated properly. Also run the V2Calibration.gcode to make sure the live z adjust is stored.

Re: Some issues with mk2

I thought the thermal runaway was simply because the cooling fan is too strong for the hot end - before I fitted e3d socks I set my fan to 50% max.

Re: Some issues with mk2

I thought the thermal runaway was simply because the cooling fan is too strong for the hot end - before I fitted e3d socks I set my fan to 50% max.

No, that is just one cause of a possible thermal runaway.

Re: Some issues with mk2

The thermal error was from the full speed fan thanks Simon for the link.
Andrew you were right i set it to 30% max and its ok now 🙂

i have run the v2calibration many times i don't think that to store live z adjustment need to re run it (or i mistaken here ?) the value
remain from the last print but on the next i need to change it again and not always to the same direction

Re: Some issues with mk2

I thought the thermal runaway was simply because the cooling fan is too strong for the hot end - before I fitted e3d socks I set my fan to 50% max.

No. The part cooling fan can be on 100% and does not affect the extruder temperature at all (except for the initial drop when the fan is turned on). This was a common theory here before the thermistor connector was found to be very problematic.

Re: Some issues with mk2

The thermal error was from the full speed fan thanks Simon for the link.
Andrew you were right i set it to 30% max and its ok now 🙂

i have run the v2calibration many times i don't think that to store live z adjustment need to re run it (or i mistaken here ?) the value
remain from the last print but on the next i need to change it again and not always to the same direction

you are right, live z adjust is independent from v2calibration.

Re: Some issues with mk2

There are several posts regarding thermal over run that have apparently been solved by reducing the fan speed.

Once I fitted e3d socks I can run my fan speed 100% again. If I had a faulty thermistor connector wouldn't it still be faulty regardless of a) the fan speed, and b) the hotend now wearing socks ? (the socks to not affect or interfere with the thermistor connection)

I'd also suggest that a faulty thermistor connector would result in very random temperature issues. The fact that I can reduce the fan speed and see a directly proportional increase is the achieved target temperature and when at 50% speed or less hold the target temperature 100% perfectly suggests to me that it's directly related to the fan.

Re: Some issues with mk2

There are several posts regarding thermal over run that have apparently been solved by reducing the fan speed.

Once I fitted e3d socks I can run my fan speed 100% again. If I had a faulty thermistor connector wouldn't it still be faulty regardless of a) the fan speed, and b) the hotend now wearing socks ? (the socks to not affect or interfere with the thermistor connection)

I'd also suggest that a faulty thermistor connector would result in very random temperature issues. The fact that I can reduce the fan speed and see a directly proportional increase is the achieved target temperature and when at 50% speed or less hold the target temperature 100% perfectly suggests to me that it's directly related to the fan.

Then I would suggest you have a somehow faulty unit. I can turn on the part fan to 100% and except for the initial drop (as expected) the extruder catches up to the target temperature in a few seconds. I have only been printing up to 260 deg C though. If you have a specific scenario I can try and replicate it.

EDIT: With or without the e3d sock...

A short video showing the temperature behaviour on my MK2 when turning on the part fan to 100%.
https://goo.gl/photos/RJUioayqv5CqAdo89

Re: Some issues with mk2

If you search this forum you will find several accounts of people with the same issue - turning the fan speed down has been the solution.

Are you suggesting that all these people actually have faulty units ?

Re: Some issues with mk2

From the knowledge base here - http://help.prusa3d.com/mk2-electronics/thermal-runaway-and-temperature-drops#_ga=1.142234226.1151335510.1474535168

Check the fan power settings aren't too high in your slicer of choice and your material temperature. (100% fan is only doable with nozzle temperatures around 200°C with the V6.1 hotend. See below.)

Re: Some issues with mk2

From the knowledge base here - http://help.prusa3d.com/mk2-electronics/thermal-runaway-and-temperature-drops#_ga=1.142234226.1151335510.1474535168

Check the fan power settings aren't too high in your slicer of choice and your material temperature. (100% fan is only doable with nozzle temperatures around 200°C with the V6.1 hotend. See below.)

I know this statement was added recently after all the discussions in this forum being basically closed by the recommendation to turn down the part cooling fan if you have thermal runaways or temperature fluctuations. As I mentioned in one of those threads replying to PJR who too recommended this as a solution that the part fan does not explain any of these symptoms.

Maybe I am missing something but the e3d has no problems holding the temperature well above 200 deg C with 100% nozzle fan on.

I made a small video, maybe I am doing it wrong.

https://goo.gl/photos/Lpjw9m5yvGhoG1Sr7

Re: Some issues with mk2

Err - your part cooling fan isn't on.

In all the shots that show the fan in your video - the fan is not spinning.....

Re: Some issues with mk2

Err - your part cooling fan isn't on.

In all the shots that show the fan in your video - the fan is not spinning.....

There are only two fans on the MK2. And only one fan can be controlled on the LCD screen. And you can see me turning it up to 255. Not sure what you are getting at. You can even hear it blowing like crazy when I confirm the 255. And I am panning to it so you can see it spinning.

EDIT: you can see it turning at 0:33 right after I am setting it to 255

Re: Some issues with mk2

and at 2:00 - without you turning the fan off - it isn't spinning....

Re: Some issues with mk2

and at 2:00 - without you turning the fan off - it isn't spinning....

Right after I turned it off by selecting Cooldown in the menu.

Re: Some issues with mk2

Andrew

Simon did turn his fan off when selecting "Cool Down".

Likewise I did a similar test and posted graphics with the extruder at 260 degrees at only 0.25mm nozzle height (I have the dimple to prove it) and with the fan on at 100%.

It is very unlikely that there is that much difference between extruder heaters without there being another problem contributing to temperature drop.

Peter

Re: Some issues with mk2

Sorry - if you did I missed that.

I'm not sure why you are flying in the face of all the examples on here that show turning the fan down solves the issue, or against the advice given directly by Prusa though. A dodgey connection would be dodgey regardless of the fan speed.....

Perhaps you haven't got the fan shroud fitted properly ? you can block half the outlet if it isn't located inside the shroud fully.

Either way, my advice would be that if you have thermal runaway issues after layer one and your fan is on 100% - turn it down. If you still have issues then you might have a connection/thermistor issue.