Bed preheat error with v3.5.x  

Re: Bed preheat error with v3.5.x

I kept getting 'BED PREHEAT ERROR' at the same points in some prints - re-start, and it it would fail at exactly the same layer.

Most likely your cables are broken. Either the heater cables or temperature sensor cable.
Regarding layer shifts, just deactivate the collisions detection like all of us.

Re: Bed preheat error with v3.5.x

Did you read the previous post?
I have had NO further issues since downgrading to v3.4.2 - yet with both v3.5.0 and v3.5.1 some print files ALWAYS failed at the same layer - yet now those same files work with v3.4.2.
Also, NO further XY shifts since downgrading.
Seems to me that v3.5.x is buggy.

Re: Bed preheat error with v3.5.x

Did you read the previous post?
I have had NO further issues since downgrading to v3.4.2 - yet with both v3.5.0 and v3.5.1 some print files ALWAYS failed at the same layer - yet now those same files work with v3.4.2.
Also, NO further XY shifts since downgrading.
Seems to me that v3.5.x is buggy.

No need to get offensive. Most of the time people are posting in the forum to get help or get some new ideas.

Temperature issues are very often caused by broken cables. Anyway, there are already couple issues open on github. If you really think it's only because FW, feel free to contribute for example here:
https://github.com/prusa3d/Prusa-Firmware/issues/1362

Re: Bed preheat error with v3.5.x

I've had weird things like this occur between different firmware changes and it was not broken wires.

Way back with the MK2S during one of the firmwares i upgraded and suddenly i kept having thermal runaway errors where the bed was constantly losing temperature. nothing i tired worked and i rolled back one version of firmware and the problem stopped. i tired factory reset and i went through all the wires with continuity testing never found a problem. again the early firmware worked fine. i waited a few months and there was 2 more firmware revisions i used the newest and my thermal runaway bed issue stopped.

there was no reason why my machine had this issue and i could never explain it. however you are not alone in seeing weirdness with new firmware upgrades. all the sensors and components could have tolerances that are just on the edge of bad but still work and different firmwares might have slight changes to thresholds where one firmware will allow you to squeak by while another is more rigid in allowing the machine to work.

going back to my firmware issue on the MK2S the bad firmware caused my Bed light to blink all the time it never went stable for long periods it acted like a broken wire but there was no broken wire. rolling back to the older firmware and the bed light would blink reach temp and stay stable.

now you could just double check your bed connections make sure everything is seated in the rambo, also check your bed temp sensor and make sure the klapton tape is holding it against the bed in the center properly.

Re: Bed preheat error with v3.5.x

I also have same error. It happens only when printing ABS and it happens at second (or third, depends on object size) layer when bed temp needs to raise to 105 degrees. Changing "other layers temp" down to 100 helps.
Since this is happening from version 3.5 and it DOESN'T happen with v.3.4.2 i'm 100% sure that it's NOT wire problem but purely software error. Similar like those extruder hiccups 10 degrees down every now and then. Luckily i've never had broken print because of those temp hiccups (yet).

From my observations it seems that when bed needs to go up from 100 to 105 error timer is too short and sends error too soon. Bed is clearly not capable of heating up that fast. I get error when bed is appr. 102-103 degrees (heating up to 105).

Re: Bed preheat error with v3.5.x

I am having the same error. I can run the temperature calibrations with no issues, it only happens when printing ABS. I thought may be it was something I was doing, as I have not been printing ABS before, only PLA. I have tested the sensors and the heat bed and wiring. All are within specs... I guess I may need to go back to 3.4.2...

Re: Bed preheat error with v3.5.x

Do you guys have an issue holding the set temperature (either bed or nozzle) ?

Re: Bed preheat error with v3.5.x

Hi,
same issue here.
MK3, 5 days old, FW 3.51

Printing PETG with slic3r PE default settings
While bed temp rises from 230 °--> 240° --> pre heat error (shortly after fan starts to blow.)

🙁
Fan design issue?

Please support.
Cheers
Kai

Re: Bed preheat error with v3.5.x

Hi,
same issue here.
MK3, 5 days old, FW 3.51

Printing PETG with slic3r PE default settings
While bed temp rises from 230 °--> 240° --> pre heat error (shortly after fan starts to blow.)

🙁
Fan design issue?

Please support.
Cheers
Kai

Hi Kai,

The default PET settings are just not good.
Set nozzle temp to 240C for first layer and other layers. Set bed temp to 85 for the first layer and other layers.
Depending on your environment, the object you're printing and the PID settings of your printer, the higher target temperature can't be reached fast enough.

No design issues, just regular configuration tweaking in the slicer.

Re: Bed preheat error with v3.5.x

Hi. Yesterday I was trying to print an ABS piece. When de bed temperature raised to 100ºC began the first layers , the layer ends and the bed set for the second was 110ºC, before reach this bed temperature the display showed “BED PREHEAT ERROR” I try to print again and the same error was displayed . Today I download to my printer(i3-MK3)the firmware V3.4.1 and don’t show the error. Is a firmware bug?

Re: Bed preheat error with v3.5.x

Same issue here.
Printing ABS, first layer (bed temp. 100C) prints ok, at second layer bed temp. is set to 110C (Slic3r PE default), temperature rises very slowly to 108 or 109C and then, bang ! BED PREHEAT ERROR, and the print is killed.
Going back to FW 3.4.2 does help.
Occurs with some parts, and not with others.. very strange !
Room is at 16-17C, heating to 20C or more could help, but this is not an issue for me.

The print could be ok with bed at 108C, but the software does kill the prtnt !!! Stupid, no ???
This error could be changed to a warning, with printer set in pause mode for example.
HTH

Re: Bed preheat error with v3.5.x

Hi Kai,

The default PET settings are just not good.
Set nozzle temp to 240C for first layer and other layers. Set bed temp to 85 for the first layer and other layers.
Depending on your environment, the object you're printing and the PID settings of your printer, the higher target temperature can't be reached fast enough.

No design issues, just regular configuration tweaking in the slicer.

Right, meanwhile I did sort that out too :-).
Unfortunately the PETG starts stringing on very small objects 0.4 nozzle with 240C - were ~225C works...
Had the hope Prusa team would set these defaults suitable for their filament... ?! 😎

Re: Bed preheat error with v3.5.x

FWIW, I "upgraded" to FW 3.5.x a few days ago.

Now I am getting "PREHEAT ERROR" when printing a model with PLA, always at the same point (Z=1.2) and always during a tool change, at the point the temperature is increased by 2 degrees in preparation for loading the new filament.

This is definitely firmware related. For me, the work-around was to keep the temps constant (which can cause slightly worse tips). The other work-around is to revert to 3.4.x until this fault is fixed.

Peter

Re: Bed preheat error with v3.5.x

I am having the same issue with 3.5.1, Prusa PETG default settings, Extruder 230C first layer, 240C other layers, Bed first layer 85C, other layers 90C. Cooling fan disabled for the first 3 layers.

On the third layer, the fan comes on. In a few seconds, I get the "Bed Preheat Error". I tried this last night and this morning.

Note that the fan remains on after the error. I think the fan not turning off is a benign "bug", but would be nice not to have my fan running until I start preheating for another print or cycle the power.

This same problem happened on a previous version of firmware when I printed items with a small x-y footprint in the center of the build area. The problem went away by offsetting the print away from the center, where the temperature probe is located.

So I tried that again just now, moving the item printed to the side of center on the build plate. Note that I did not power cycle the printer between prints. This time, the printer did the Z calibration, went to the front corner and lowered to do a wipe. Paused maybe 10 seconds, then powered down the bed and hotend heater. No error messages. Just displaying "Prusa i3 mk2.5 Ready" like nothing happened. Another sign that the "Bed Preheat Error" is not cleaning up correctly.

I power cycled the printer. Retried the same print. The hotend dropped 5 degrees when the fan came on, but the bed stayed steady at 80C. Did not get the error. Printing fine.

Re: Bed preheat error with v3.5.x

Ok, seems to fix the 'problem' mostly.
What I do not understand: Why does (sometimes) an error occur if the 1st to 2nd layer temp difference is 10°C or more... .
It seems that if the bed does not heat up fast enough this happens. But if so: Why can you define a 10°C spread in the Slicer?
THX
Kai

Re: Bed preheat error with v3.5.x

Ok, seems to fix the 'problem' mostly.
What I do not understand: Why does (sometimes) an error occur if the 1st to 2nd layer temp difference is 10°C or more... .
It seems that if the bed does not heat up fast enough this happens. But if so: Why can you define a 10°C spread in the Slicer?

Current firmware is very aggressive on the bed temp check. If you print PLA, you're turn the fan on from the second layer. In case you're printing small object, you're blowing cold air on the bed and trying to heat it up at the same time. But if you print a big object, the bed is covered with plastic and can is able to heat up fast enough.
Slic3r does not limit you in your settings. Maybe you want to achieve something special (not common) and Slic3r shouldn't be in your way. In general I don't understand the default setting with this 10C temp difference.

Re: Bed preheat error with v3.5.x

I had this problem,too. Small part in center = Bed preheat error. Just moving it off center eliminated the issue. With bigger parts I guess the fan doesn't dwell long enough on the area around the sensor to trip it.

Re: Bed preheat error with v3.5.x

10 minutes to go in a 47 hour print I get this PREHEAT ERROR
Could it be more depressing?
I do think it is software related more than a hardware issue
Print failed with hotend over the wipetower. It had been 100k times over that area in the same print with no error
BTW - I am not using PRUSA's FW, but Zero's. Slicing was done with 1.42 alpha3

Re: Bed preheat error with v3.5.x

I was wrong. There was a broken wire in the heatbed. Not completely, but enough to produce one heatbed error in maybe each 200 hours of printing. The wire finally broke completely and the failure was then easy to assess and repair. I guess that textile seath did not work as well as expected or maybe the wiring bundle was just one inch too long and the S curve the wiring did finally ended up ruining one of the wires