FW update bricked 4 printers  

RE: FW update bricked 4 printers

I had a different problem after firmware upgrade but it was solved by doing a factory reset. Could it help you too?

RE: FW update bricked 4 printers

see Prusa's thermal-model-calibration.

RE: FW update bricked 4 printers

As for the thermal model, it is for the extruder. Not the bed. The issue is that when printing at 100c on the bed, if enabling the part fan cooling, the droop of is too steep. Because the bed is not getting enough power. It is a real issue, as if in idle the temp stays fine, even with the part fan on full speed. This also works on older FW and SW, so somewhere along the way, Prusa messed up.

So again, the issue is bed temp. It drops like there is no tomorrow. Reverting to the oldest Prusa slicer I can find, and the oldest FW, it suddenly works fine, and the temp do not drop.

RE: FW update bricked 4 printers

As for hardware reset, I haven't tried that. I guess I should give it a try. Just reverting to old FW and SW solves the issue completely, but a complete reboot might do the trick. Thanks for the advice.

RE: FW update bricked 4 printers

Hardware reset does nothing to bed temp. After spending about 24 hours on this issue, using 4 different printers, all behaving exactly the same, for absolutely every change, I got it working. Somewhat. Juice is less to the bed, but it seems predictable and stable now.

Just for reference, at one point I could not even get 80C on the bed to work beyond the first layer. Something got seriously corrupted, I just do not know why and what caused it. I actually had to revert to the oldest FW I could find, wipe my windows of anything Prusa, reinstall the SW, and rebuild every profile from scratch. That includes manually deleting all Prusa settings in the hidden user folder.

The first printer that failed, simply could not print the same gcode as the others. I actually ordered parts to replace wires and stuff, to fix that one. Once I flashed the other 3 printers, they failed at the exact same time. Funny having 3 printers printing the same job, starting them at the exact same time, for them to fail simultaneously. Using gcode they just had printed fine.

After a total cleanup, that fixed the corruption what ever that was, if you try to print with part fan at 100% and bed above 90C, it throws a thermal runaway error. It simply cannot heat the beds beyond about 93C. It is not a thermal runaway issue, it is simply the printer not supporting 100% fan speed beyond about 90C on the bed. That is in a low 20sC ambient temp.

I just have to repeat, that all printers failed printing the same gcode, after FW flashing. At the same time, beeping in harmony. An orchestra of failure. Just to be clear: This is not user error. This is changing the character and ability of the printer, by SW, and not telling about it. I am moving on, and there probably is a reason for the change, it might be perfectly valid, but not telling about it, not informing us, is just wrong. It will not affect most users, apart from potentially messing up files and settings with no solution given what so ever, sending users on a ghost chase and shopping spree to fix perfectly fine printers.

The thing is, that few people print the way that I do, with this kind of temp and this kind of fan setting. Not at this stage. I am not even sure Prusa knows about this issue them selves.

So, after days of fixing this. If you run into a sudden thermal run away beeing mk3 printer after FW flash, try lowering bed temp expectations to about 90C if running high part cooling fan. You might have corruption somewhere and might need to reinstall and make all your profiles from scratch, like in not importing any of your old files into your SW, and redo everything from scratch. They updated something critical, just never told us.

RE: FW update bricked 4 printers

Does it help to move the part around the bed, away from the location where the temperature sensor is taped to? That is, if the part is not too large to do  so. Are your printers modded? In what environment do you print? Can you provide a zipped sample .3mf file? 

At work, only one of our two MK3s shows thermal runaway on extruder, not bed. They sit in Prusa enclosures. At home I am happy to stick with 3.12.2-5713 for the time being.

Thank you for the feedback.

RE: FW update bricked 4 printers

Since these are my primary work horse, I had to sort this out.

There is a ton of moving parts in my work, and what probably have happened is that after servicing one printer, and altering the print profile to way more aggressive fan usage, I probably somehow got lost in the changes. I still do not understand that 3 of my 4 four printers failed after a FW flash, because I did not clean them. I really do not have time for this, but here is where I am:

I print using PETG exclusively. I print a ton with zero bottom layers, as in mesh. On all my printers, if I go to calibrate>auto home. Then move x to 100 an Y 100 and set fan 196 (settings>temp>fan) all my printers just barely manages to heat the bed at 90C. If I set fan at 255 (100%) I think the max bed temp that is stable is about 74C. I still use stock fans, bought from Prusa.

So, given the known issue with the hole in the right front corner of the bed, my current work is a nightmare as I need to use the space. I cannot use the cooling fan above 77%, as that will result in wildly fluctuation of the bed temp, and thus loss of bed adhesion and warping. I also heatsink the bed for 9-30min, and print all layers on 90C on the bed. I have to use fan on all layers but the first one, due to the nature of what I print, read, as in mesh.

I used to print at 70% fan speed, and my fans probably lost a bit of performance due to lacky maintenance. I never realized that I was a very edge of the beds capabilities. I also ordered a new bed cable, threw a retailer, but it is sourced from Prusa by him. That changed nothing on the printer in question.

I also reverted to the oldest FW I could find, and the bed temp behavior is the same, with that firmware. I clearly had some form of corruption somewhere in my system, but it was confusing, still is, and I just need to move on.

But given the experience I just had, it is pretty obvious, that the cooling fan speed will mess up a ton of prints. The bed is pretty powerful for its size, and to me it is pretty choking how quickly that fan can cool the bed. This is doomed to result in thermal expansion and contractions, resulting in all sorts of fun forces on the printed part. The need to go to the lower 70C range for using 100% cooling fan, well, that was new to me.

Also, we are using a steel plate, a pretty thick one. It really don't matter all that much how thick the bedplate is, because the thermal interface between the bed and the steel plate is poor, and the conductivity of the plate is also poor. But 74C at 100% cooling fan?

I am still bewildered by this, because for smaller parts in which the fan is by default ramped up to cool the layers, like to 100%, that causes a thermal run away on all my printers, at 90C bed temp. Why this is not a well known issue, I simply do not know.

So again. Auto home, x=100 Y=100 fan=255. The max stable bedtemp I get, with just an empty bed, is about 74C. On all my printers, on all the firmware versions available. For 90C bed temp, the limit is about 194 on the cooling fan. Or about 77% in the slicer.

For the record, after dialing this all in, the fixed bed temp, the heat soak, 3mm square on flow, and 77% fan max, warping is significantly reduced. Print quality is really nice, but man, this is slooooooooooow. Given the max fan is hardware limit, the only way to increase cooling, is to slow down. Cannot reduce bed temp either, kinda need the print to stick to the bed.

This is not Prusa related, not even mk3 or whatever related either. Physics is what it is. Just never ever heard about this before, nor the effects that goes with it. No wonder my prints warped when the fan kicked in for that bridge layer. There were like 5-6C bed temp drop as the fan passed.