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
The root cause is that Prusa didn't design the printer with cables that are actually built to flex repeatedly. They're hardly alone in this, but I wish more printer companies would use components suitable for the intended purpose. It's not like this is an unsolved problem.
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
The root cause is that Prusa didn't design the printer with cables that are actually built to flex repeatedly. They're hardly alone in this, but I wish more printer companies would use components suitable for the intended purpose. It's not like this is an unsolved problem.
The truth is that I changed the wires with some silicon seath high quality AWG12 wires with many more strands (therefore though thicker much more flexible - and pretty more expensive too) than the stock ones, that yes, I agree with you and I must admit they were a bit shitty and not really suitable for the task, as my experience dictate. Printing a chain to protect the wiring instead of that textile thing might not be a bad idea but printing more printer parts is a sort of "metaprinting" and I am kind of sick of it already. I don't know if it is the same when you buy a Makerbot, but with my PRUSA I had to print some proper spool holders, also the side trays, and the light support, then some parts to get the MMU2 inside the ikea lack, and then I had to invest a lot of time designing, printing and testing an extruder that could make the MMU2 work. It was either that or just asuming that I had done an appalling purchase with the MMU2. So I'd say that I'm happy enough now that my MK3+MMU2 works well enough and it is working on something other than repairing itself.
So being optimistic, the best that can be said about PRUSA's printer is that there are plenty of fields of improvement on it. Not only the firmware or the hardware, but also things as basic as the quality of the wires. I have no doubt that it is possible to make a good printer out of a PRUSA because mine is today a bit better than yesterday.
Re: Bed preheat error with v3.5.x
I don't know if it is the same when you buy a Makerbot
Keeping in mind that a Makerbot is a low-end Stratasys, and comes with a price tag to match.
There's basically nothing left of the hobby-level RepRap left in current Makerbots.
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.
You absolutely right. It is definitively a bug. I tried to print this part for calibration purpose https://www.thingiverse.com/thing:2267549 . As said in Thingiverse single perimeter, 0% infill, and no top solid layers, located right in the middle of the heatbed 😀
As it was in ABS I activated a bit of the fan to avoid curling corner. In case someone else want to reproduce the bug, here are my fan presets :
First time, at 6mm layer height I got the Bed Prehat Error with both fan keeping cooling after the print stop.
Second time, same layer height, I got no message error but print stop with "Prusa ready" displayed with both fan on too.
So I check the forum, find this post and I move my print to a corner and then I got no issue at all, the print finish perfectly fine.
So the fan cooling the thermistor is not appreciated and an update of the firmware would be great for the next version.
BTW I am running the last one, 3.6.0 with Slice 1.42 alpha 4.
Re: Bed preheat error with v3.5.x
I just want to add that the error occured after the temperature reach the 110°C. My first layer is at 100°C and then it took several minutes to reach the target temperature and then the error happened.
Re: Bed preheat error with v3.5.x
I just got this same error while printing with ABS using all standard settings EXCEPT I turned the fan on, using the default fan profile. Previous to this I had made many ABS prints over the last month or so, with the fan disabled.
I agree this is definitely a bug in 3.5.x, and NOT a wiring issue.
Frank
Re: Bed preheat error with v3.5.x
I just got this same error while printing with ABS using all standard settings EXCEPT I turned the fan on, using the default fan profile. Previous to this I had made many ABS prints over the last month or so, with the fan disabled.
I agree this is definitely a bug in 3.5.x, and NOT a wiring issue.
Frank
If you turn the fan on, it makes the bed heater work harder to maintain temperature. The ABS bed setting (110C) is close to the limit of the heater, and it's likely that when you turn the fan on it can't maintain temperature. Stopping the print if the bed can't maintain temp is an important safety feature, not a bug in the firmware.
Try running the fan at 25% and see if that works. I had a similar problem with ABS and 25% fan worked for me.
Re: Bed preheat error with v3.5.x
Anyone know if 3.6.0 fixes this issue?
Re: Bed preheat error with v3.5.x
Anyone know if 3.6.0 fixes this issue?
It's not. On my MK2.5 enclosed I have even issues w/o fan and 110C.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Bed preheat error with v3.5.x
OK, time to throw in my tuppence...
Just upgraded to MK2.5S. I had a couple of other prints go just fine and then with this particular part, I am getting a PREHEAT ERROR. Always in the same place in the print. I tried a different print and it went fine. Back to the problematic print. PREHEAT ERROR. In the same place.
While playing with it, trying to figure it out, I noticed something. I was printing PETG and the settings for the print were: the hotend at 245 degrees and the heatbed at 90 degrees. But about the point in the print where the error was about to occur, I noticed that hotend temp was 230 degrees! (Still with a set point of 245). So I paused the print and let everything cool a few degrees and then unpaused the print. As expected, the printer did a preheat to bring hotend and bed back up to the set points and then the print proceeded. As soon as the printhead arrived over the part, the cooling fan came on and the hotend temp immediately dropped to 240 and then proceeded to cool further.
When the hotend reached 235, I lightly touched the cooling fan to stop it from spinning. The hotend temp started to climb back up to 245. I took my finger off the cooling fan. It started spinning again and the hotend temp started dropping again. Very repeatable.
And looking at my Slicr settings, the fan is off for the first three layers and then it turns on. And shortly thereafter, that's when the PREHEAT error occurs. (I still don't know why this is occurring with this particular print and I did not see this happen with my other prints. Maybe something with the geometry of the print that exacerbates the problem?
So, in my case, at least, it seems that the problem is not the bed temperature (throughout all of the above, the bed read 90 degrees) but rather the hotend temperature.
I have not experienced this problem before, but with the new slanted cooling fan arrangement and shroud, I wonder if the cooling fan is more efficient at cooling than it was before?
Re: Bed preheat error with v3.5.x
Follow-on to my previous post.
The object that I was printing has a fair amount of bridging down close to the print bed. I was able to get past the failure point, by aggressively turning down the fan every time it sped up for a bridging operation. Once the print was up a few millimeters from the print bed, I was able to just let the fan run at whatever speed it wanted to run and there was no excessive cooling of the hot end.
It seems that the combination of high fans speeds close to the print bed (<1.5mm) can cause the hot end to be cooled down too much...
Re: Bed preheat error with v3.5.x
For what it is worth...
I have printed a fair quantity of PLA with my MK3. I did have my heat heated thermistor come loose a few months ago and repaired it without issue.
The ABS I am using is the black ABS from Prusa.
I ran into the "BED PREHEAT ERROR" on my first attempt to print with ABS. As many other had described, it would happen after the first few layers. I eventually got the Raspberry Pi Zero W bracket to print after a few attempts. (The part that is inserted between the Pi and the Einsy board.) The first few attempts resulted in the bed preheat error. I initially tried printing the mount and the removable door on the same print. During this process I remounted my thermistor just to make sure that wasn't the problem. It did not help. Eventually I got it to work by printing the two parts individually.
I then went to print the modified Einsy base with the door modification. With the ABS presets I keep getting the bed preheat error. Upgraded to the 3.6.0 firmware and had the same problem. The fan setting was off in the presets. Tried setting the bed temperature to 105 for the first layer and 110 for later layers and had the same problem. I have successfully printed the enclosure using a first layer temp of 105 and also 105 for the subsequent layers.
While this could be a temperature fault with the thermistor or the wires I doubt it. I have purchased a new thermistor and wires for the heat bed from Prusa even though I suspect that is not the issue. I believe it is a bug in the software as noted in some posts and indicated by down-rev'ing the software to a 3.4 build.
All of this is in preparation to install my MK3S upgrade. If I'm going to spend a day working on my hardware then I wanted to do it all at once. (A bit of irony there since I sunk a bit of time into remounting the thermistor and recalibrating the printer. Change one thing at a time, right... 🙂 )
Ben
RE: Bed preheat error with v3.5.x
same here on Prusa mk3s (fw 3.6, 3.7), ABS with 20% fan, I got exact same error. Tried 3 times and it's happened on same layer height. Same print without fan and everything is ok.It's definitely firmware problem.
RE: Bed preheat error with v3.5.x
@james-t3 Have you tried to put a silicone sock on the hotend? It helps with thermal insulation both ways - prevents radiating heat heating up the part and prevents the fan cooling the heat block. It also saved me from a blob just recently ...
RE: Bed preheat error with v3.5.x
I am getting this error after "updating" from firmware 3.2.1-576 to 3.7.1 on a Prusa MK3. Can someone please tell me if a newer version fixes this error without introducing new ones? I'm printing ABS and turning on the fan and increasing the temp from 100 to 110 after the first layer.
We were forced to update as my OS was out of date, then we had to update slicer due to the new OS, and the slicer update required newer firmware. Now I'm making a lot of scrap. I'm on my fifth roll of ABS and have not had this error message until the firmware "update". Note I had been using 3.2.1 since I purchased and built the printer two years ago.
Sometimes the print works. Sometimes it fails. Software fails miserably with no means of restarting without rebooting. When it stops the fan is spinning and there is scrap on the plate. Aborting the print and restarting gives numerous errors. Have to turn the printer off and on to continue. Numerous piles of scrap being produced. Also the GUI on the new slicer is different too so my productivity suffers greatly. There was no need to change to gui. The old one worked fine. Who do I bill my time too for all of these updates?
Loved my printer for two years and now its a love/hate thing. Please help turn this relationship around. How do we fix this?
RE: Bed preheat error with v3.5.x
Does 3.7.2 MK3 Firmware fix this? It has a change to the PreHeat Bed Temp test. I don't have a problem preheating though. It appears to be timing out when going from 100 to 110 during a print. I also notice that the Firmware changes indicate changing the PWM to the heat bed to reduce noise. Did that change affect the time it takes to go from 100 to 110 so that now we are timing out and get this new error message? I don't see anything in 3.8.0 that has to do with bed temperature timing out either.
Prusa please help us. 3.2.1 worked fine. Now printer is broken.
RE: Bed preheat error with v3.5.x
I couldn’t even get the bed heated past 75c. With out getting the error no matter what. Installed 3.4.2 no issues. Also had part cooling fan issues with 3.5.1. On the older fw that’s no longer an issue.